This is the second in a series of posts that will be reviewing and responding to the arguments of Dr. Feser's The Last Superstition. This was part 1. I haven't read many books of philosophy, and none aimed at popular audiences, so when I note that Dr. Feser starts out with a list of claims that he promises to demonstrate later, I have no idea if that is standard procedure or not. It does make the first chapter, Bad Religion, devoid of meaningful content with regard to establishing Dr. Feser's claims. However, one of the things I want to do is to in this post is list all these promises Dr. Feser makes in Chapter 1. After I review the last chapter, I will return to this list and we will see what has actually been proven.
Claims Dr. Feser says he will demonstrate
Secularism is inherently immoral and irrational, only a specific sort of religious view can be moral, rational, and sane
On intellectual grounds, atheism can not be true
Secularism can never spring from reason; its true grounding is from a willfulness and desire for it to be true
The basic metaphysical assumptions that make atheism possible are mistaken
Secular propaganda is the source of fideism
It is as impossible to say nature has no meaning or purpose as it is to square a circle (more on that below)
Secularism is parasitic on religion for all its important ideas, it is strictly a negation
What is characterized as a war between science and religion is really a war between competing metaphysical systems
The classical metaphysical picture is rationally unavoidable, and thus so is the traditional Western religious view derived from it
Given atheism and naturalism, there is no persuasive argument that allows you to trust in either reason or morality
Edit on 2009-NOV-17 to add: The abandonment of Aristotle's metaphysics has led to the abandonment of any rational or moral standards that can be used to justify moral positions, and is responsible for the curent civilizational crisis of the West.
Dr. Feser allows himself a full 241 pages in the next five chapters to accomplish all this. Of course, with so modest an undertaking, he leaves himself plenty of space to continue to denigrate atheism, secularism, the New Atheists (Dawkins, Dennett, Harris, and Hitchens), Hume, and many more in those chapters as well.
I do have a few other comments on some of Dr. Feser's remarks in chapter 1. While I still intend to avoid responding to the mere demagoguery that he indulges himself in, there are a few points that reveal interesting and noteworthy aspects of both him and his opinion of his audience.
There is nothing particularly noteworthy or striking about his claim that the less people know, they less they realize their ignorance. In fact, I read similar thoughts from a variety of science books and scientists growing up, typically along the lines of 'The more you know, the more you realize how little you know'.
I do not agree that attempts to account for phenomena such as the mind without referencing God is a religious discussion. You might as well say that attempts to account for lightning without referencing God is a religious discussion. Then again, perhaps Dr. Feser would say that. I would not be surprised at all to see him claim that any discussion of any natural phenomenon is inherently religious.
One of the common hallmarks of purveyors of woo is a sense of persecution that results from being treated equally. This comes out twice in Chapter 1, where first Dr. Feser complains that some philosophical positions distasteful to him are considered still worth discussion even when they can't be demonstrated, while the subject of religion is considered not to have made its case. Of course, the second standard is a far higher hurdle than the first, and certainly not to be awarded lightly. To imply that religion must be granted the second when other positions are granted the first, or else the supporters of the second are receiving unfair treatment, sounds very much like a persecution complex. Shortly after that, he complains that the distasteful propositions are referred to as making people think, whereas in this context religion is apparently not worthy of a moment's notice. He acknowledges that most people are raised religiously, but somehow misses the point that immersing people in thoughts they already find comfortable will be doing the opposite of making them think, it is much more likely to lull them to stupor. However, the concern seems to be for some sort of time equality, not purpose, because otherwise religious ideas are just not being treated fairly.
Dr. Feser pulls out the old saw about the desire to disbelieve in hellfire being a motivation for atheism. Oddly, I have met very few Christians who believed they, personally, were going to hell. I certainly never did, back in the day. He doesn't seem to understand the human tendency for exceptionalism, or to be deliberately ignoring it.
Dr. Feser declares that the notions of a selfish gene, or design via natural selection, can only be true and interesting if by these terms we attribute some superhuman, literal intelligence to the gene and the process. I'm not sure what to make of this. Obviously he knows the terms are metaphors that describe the complex interactions of various feedbacks mechanisms. He doesn't think that the study of feedback mechanisms is interesting, that the feedback mechanisms are not true, or that the use of metaphor makes the concept untrue or uninteresting?
Dr. Feser complains about 'Easter Bunny comparisons to God', which he disdains. This is all fine for him, but the authors upon whom he heaps this disdain are do not have the audience of his peers in mind; their books are for the general public, and often specifically the religious members thereof. The Easter Bunny example actually strikes right at the heart of what many of these people believe. If the religious group doesn't have their followers trained in the ideas of Aristotle, why should it be the job of Dennett, et. al., to train them? Later on, Dr. Feser says that this is an example of these authors not being willing to take on the real issues against the formidable opposition. With all the diminutions hurled against these authors, you would think he believe this is the appropriate level of opposition for them, but I suppose he thinks even more poorly of his fellow believers in this regard. At any rate, while I might not have the training of a Dennett, I am happy to accommodate Dr. Feser by engaging his ideas directly. Having read through Chapter 4 so far, I have not found any reason to see his presentation of reason, faith, and religion as having a superior metaphysical basis to your typical Sunday preacher.
Finally, Dr. Feser likes to make great use out of the metaphysical absurdity of square circles. He is unaware that all circles are indeed squares, under the taxicab metric (I'll devote a separate post to that). This is a problem with his metaphysical analysis that we’ll cover in more detail later. For now, let’s just say that like any other formal system, Aristotle’s metaphysics will turn out to be founded on arbitrarily chosen premises that are inherently improvable and not obviously better than a variety of alternatives as a description of reality.
Monday, October 19, 2009
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«Oldest ‹Older 601 – 800 of 1677 Newer› Newest»I have no idea what you're saying, in terms of the wiki examples. In the "solution" to the twin paradox, both the SR and GR explanations (as well as the one based on doppler effects) take the view the the spaceship twin is moving away, then returning.
I just re-read the three paragraphs on the GR explanation in the twin paradox article, which included the point of view that the shipboard twin (our Bob) was really stationary and the rest of the universe was undergoing acceleration. The effect of this is basically a "time contraction" that, in the point of view where Bob does not move, affects the rest fo the universe. The article specifically mentions that these ideas actually predate GR generally.
If the premise is that you cannot tell which one is moving, then the "answer" would have to be: "OK, then we can't tell you who is really younger."
Except you can, and the article explains how this is done.
The real "paradox" only arises when the claim is made (as you did) that both twin's observations are "correct," i.e. that each is younger than the other.
If you prefer, you can say that due to the delay in light transmission, neitehr twin sees something simoultaneously.
http://mentock.home.mindspring.com/twins.htm
Does not discuss the point of view Einstein did in his 1918 paper, which is discussed in the wiki article, where you can treat Bob as stationary. Maybe Mentock did not know about this point of view or how to handle it, or maybe he thought it was
Relying on different frames of references to "explain" special relativity does not in any way distinguish it from LR or Galliean relativity. That is not what makes SR what it is.
I agree.
... denies your claim that, in the wiki example, the same twin would be younger even if you reversed the assumed patterns of absolute motion.
There is not pattern of absolute motion to reverse. Mentock's article does not discuss the frame at all. I don't know if he didn't understand it or just decided to ignore it.
However, he does link to an article that discusses the paradox, including the gravitational time dilation, in plainer language than the wikipedia article. It explains both why symmetry does not apply and how to interpret events if you assume Bob (Sam, in his example) is in an inertial frame.
http://mist.npl.washington.edu/av/altvw38.html
http://math.ucr.edu/home/baez/physics/Relativity/SR/TwinParadox/twin_intro.html
Just so you don't once again miss the implications, let me repeat this part again:
"Or can Stella declare that the Earth did the travelling, so Terence is the younger?"
He is implicitly saying that IF the earth was moving, then Tereance (earth twin) WOULD be younger. He simply denies that the earth was (or could properly be considered to be) the thing which was "really" moving.
Thank you for making sure I don't miss any implications. Did you follow the link to the "Equivalence Principle Analysis"?
http://math.ucr.edu/home/baez/physics/Relativity/SR/TwinParadox/twin_gr.html
As it makes clear, in the viewpoint where Stella is motionless, Terence still ages more.
They merely show how an abolute effect can result from an absolute (not relative) motion, which is not a problem to do nor a paradox once solved.
The wiki solution does not require absolute motion.
In my example, I have presupposed an inaccurate clock, which was inaccurate to do MALFUNCTION. SR does not say that a malfunctioning clock will be corrected by time. But it does, in effect, say that all properly functioning clock are accurate even if they give radically different readings of time in different "frames of reference." Likewise, in effect, it says that clocks from other intertial frames of reference would be "automatically" corrected to agree with the frame of reference it was moved to, so that it would agree (at least henceforth) with the clocks which previously gave a different reading than it did.
Except, it doesn't claim this. There is no correcting of clocks, the clocks just behave as they have done all along. they don't change their behavior (locally).
Underlying the whole thing is basically this (as I said at the beginning here): the "correct" time is what a (properly functioning) clock says it is. If that varies from what properly functioning clocks in other frames of reference say it is, then it is still right, as is the one which reads differently in another frame of reference.
This is what I have called "putting one's faith in yardsticks" in other posts.
Underlying this complaint is the idea that there is or can be such a thing as "correct time" if only we could figure out what it was.
As I understand SR, time "really does" slow down for a moving object, and the more radically so the the closer it gets to the speed of light.
According to SR, no object can get close the speed of light. No matter what your speed is, was, or will be, light will move at the same speed from your perspective. Other opbject may see you as being close to the speed of light, but you never see yourself that way.
This leads to the paradoxical conclusion that each one "really is" younger than the other.
In different points of view, either can be younger than the other. There is no "really is".
One Brow said: "A yardstick is not a yard. The movement of a second hand is not a second. You can see the yardstick and the movement, you can't see the yard or the second. Agreed?"
Yes, I agree, and said as much in my post. I wasn't trying to make the point that a yardstick is a yard.
You directly compared seeing a yardstick to not being able to see a second, so I felt the clarification was important.
The claim I made, and assumed you agreed with, was: "Like you, I take the position that neither of them can be measured directly."
I said I thought that was a legitimate point of view and I could have a discussion under that metaphysical position. That does not mean I have adopted the position as my own. I apologize if that was confusing.
However, I don't see where either the position that rulers and clocks do measure length and time, or the position that they do not, changes the position that you can see yardsticks and movement but can't see yards and seconds. I think the latter position fits within both our viewpoints.
So did you really mean: "I think rulers and clocks do [directly] measure distance (length and duration, respectively)." If so, in what sense are you calling the measurement "direct?"
By indirect, I merely meant that there are intermediate processes and assumptions involved in me laying a yardstick on a floor and then claiming that the distance it is covering is "one yard." It is direct in the sense that you just lay the thing on the floor and say "that's it, that's a yard," but that is not what I meant when I said it is not "direct." How do you mean that it is direct? Is there any sense in which you would say the measurements are not direct?
I think it is direct in that, if there is no change in the inertial conditions, if the two points are in the same intetial frame, and there is no change to the yardstick itself, you will get the same measurement every time, and that this is also true of clocks measuring durations. Once the unit has been firmly established, the distances real for the purpose of calculating things like field strength or velocity in those units.
I do agree that unit choice is arbitrary, if that is what you mean by being not direct. I also agree that, due Heisenberg uncertainty adn the like, there are limits to the exactness of the measure.
Heh, no real gap, but just a mere "accounting error," eh? The guy supposedly ages almost 14 years in an "instant," and this is supposed make some practical (as opposed to mathematical) sense? I don't think so! Homey don't play dat.
And, in my book, anyone who does simply equates math with "practicality," the sure sign of a nerd without a lick of street cred, ya know?
The answer is in the link I quoted above by the same author.
I said: "If the premise is that you cannot tell which one is moving, then the "answer" would have to be: "OK, then we can't tell you who is really younger."
You said: "Except you can, and the article explains how this is done."
Which article, wiki? "You can" what? Tell which one is moving? Of course, you can, the whole bogus "solution" presumes it. Or do you mean "can tell which one is really younger, without knowing which one "stayed home" and which one "turned around" after going off into space? If that's what you mean, how does it explain it?
=====
I said: "... denies your claim that, in the wiki example, the same twin would be younger even if you reversed the assumed patterns of absolute motion."
You responded: "There is not pattern of absolute motion to reverse. Mentock's article does not discuss the frame at all."
1. Sure he mentions it, and I already quoted it: "If we allow Ann to return, we've only restated the problem with the names switched." If you can't understand what that means, then just forget it, I don't want to argue about it, it's not important anyway.
2. I have already told you what I mean by "absolute motion," and it is the same meaning that the wiki problem is giving it when stating the problem. No doubt you have your own *special* definition which you will insist on applying in every situation, regardless of context or the intention of the author. Let me guess: For you, "absolute motion" can ONLY mean (for anyone who ever uses the term) motion which can be compared to something which can be proven to be at absolute rest, such as the ether. Right? That is not how I am using it, and that concept is not one which any author we've seen trying to "explain" this paradox relies on.
Thank you for making sure I don't miss any implications. Did you follow the link to the "Equivalence Principle Analysis"?
Yeah, I did, did you? Several points can be made about that page:
1. To begin with, he makes it clear that it is not used to solve the problem from a GR standpoint, and it can't be used to the solve the problem from an SR viewpoint either, because.SR does not have an "equivalence principal:" "The Equivalence Principle analysis of the twin paradox does not use any real gravity, and so does not use any General Relativity. (General Relativity is the study of real gravitational fields, not pseudo ones, so it has nothing to say about the twin paradox.) ...it needs to be emphasised that we are not using any actual General Relativity here, and no one ever needs to, to analyse the paradox."
2. He says "We are simply grabbing a result about real gravitational fields from General Relativity," and is then going to apply it to SR. But what, exactly, is he applying it to? He makes it clear that it is "the usual problem," i.e. the one which posits, from the outset, that Stella is moving away from earth and Terence remains motionless. There can be no "turn-around" without motion---without someone going somewhere, and then turning around. Yet he incorporates the turn-around: "we conclude that Terence ages years during Stella's turnaround." Note that he does NOT say "during Terence's turn-around"." Indeed, like the other guy, he now tries to impute motion to Terence (contrary to the problems explicit assumptions to begin with: "Terence, on the other hand, does not stay motionless in Stella's frame. The field causes him to accelerate"
3. Even in GR, gravity is "equivalent to" acceleration, and this guy makes it clear that this explanation does NOT solve the problem: "But remember, this is not an explanation of the twin paradox. It's simply a description of it in terms of a pseudo gravitational field. The fact that we can do this results from an analysis of accelerated frames within the context of Special Relativity." So the acceleration is still there. Is this explicit "non-solution" (according to this author) the big "explanation" you are wanting me to acknowlege?
One Brow said: "Thank you for making sure I don't miss any implications."
After reading your posts, I'm still not clear about what you think is being said in these "explanations." Let me just ask you: Do you still claim that the same twin (the one who happens to be on the rocket ship) will always be younger, regardless of whether you treat the ship or the earth as the thing that is moving?
One Brow said: "In different points of view, either can be younger than the other. There is no "really is".
Then why do you insist that pages of bogus explanations which purport to prove that one twin REALLY IS younger are reliable, I wonder?
I said: "As I understand SR, time "really does" slow down for a moving object, and the more radically so the the closer it gets to the speed of light."
You responded: "According to SR, no object can get close the speed of light."
You could have saved a lot of governments many billions of dollars if you'd only informed them of this before they went around buildin all kinda "particle accelerators," ya know? Them fools actually think they are accelerating particles to, like, .999c.
"As it makes clear, in the viewpoint where Stella is motionless, Terence still ages more."
As shown above, she accelerates either way. This is just a (bogus) way to create a scenario where she "thinks" she isn't moving, and one which does NOT purport to solve the twin paradox. The guy made it very clear, on his first page, what the real solution is: There is no paradox because one, and only one, is moving and the other can't be construed as moving.
I said: "And, in my book, anyone who does simply equates math with "practicality," the sure sign of a nerd without a lick of street cred, ya know?"
You said: "The answer is in the link I quoted above by the same author."
Which link? Which author? I think you mean the same one I am quoting, who says a guy will age 14 years in zero time.
Let me just ask you: Do you think this is what would "really" happen?
I asked: Let me just ask you: "Do you think this is what would "really" happen?"
I mean, really? If someone happens to be observing me in such a way that I seem to be aging 14 years instantaneously, will it happen to me? Suppose one person saw me aging 14 years, and another saw me aging 50 years in the same instant? Would I do both, and thereby age a total of 64 years instantly, or what? The whole problem with some of these SR analyses, and the theory in general, is that it can't seem to separate false appearances from reality.
Or, as I said originally, can't seem to separate mathematical "truth" from practical truth.
I said: "As shown above, she accelerates either way. This is just a (bogus) way to create a scenario where she "thinks" she isn't moving, and one which does NOT purport to solve the twin paradox."
Let me elaborate on this point, using the author's own words, because I have a feeling you will not see the point without it being explicitly brought to your attention.
1. Is Stella "really" turning around in this "analysis" and only think that she is remaing motionless, or
2. Is she really remaining motionless?
"When she ignites her thrusters for the turnaround, she can assume that a uniform pseudo-gravitational field suddenly permeates the universe; the field exactly cancels the force of her thrusters, so she stays motionless."
Notice that she is only "assuming" a pseudo-force when, in fact, she has turned on her thrusters and, as it says, "turns-around." She does NOT stay motionless (despite his later wording which might easily mislead you if that's ALL you read). She convinces herself that she is "motionless" by (falsely) assuming that a psuedo-force, which "exactly cancels" (in her mind) the thruster force is, in fact, turning her around. Again, this is made clear in the premise of the scenario from the outset, and the author specifically says, he is still applying here (not a new scenario).
If we start with the premise that all motion is relative (which it is) then it is an obvious oxymoron to speak of absolute motion. But, within the confines of relative motion, some motion is known to be "real" or "absolute" as between the specific objects being compared.
Take these two objects, for example: (1) A car going over the surface of the earth at a constant rate of 60 mph ("relative to" the earth, of course) and (2) the earth itself (as well as all things affixed to it, such as trees, stop signs planted in the ground, etc.) If the car is travelling west, then we say that the car is "really" moving west relative to points on the earth, rather than remaining motionless while the earth, and all objects affixed to it, are moving east at the rate of 60 mph relative to the car.
This case must be considered distinct from relative motion, also known as "apparent motion" in terms of SR & GR, which would be:
A car is moving across the surface of the earth at the relative rate of 60 mph. The distance between the car and a fixed point on the earth (say the Empire State Building in New York City) keeps increasing, but nobody can ever say which object (car or building) is "really" moving, even relative to each other, because all motion is totally and completely relative. The building could just as easily be moving away from the car as it could be remaining absolutely motionless while the car moves west. Maybe they are both moving for that matter. They are separating at the rate of 60 mph, but that could be because the car is moving west at 30 mph while the building is moving east at 30 mph (relative to a point in between the two, like a telephone pole).
"Absolute" motion (as I am using it, and as wiki is using in setting up the paradox problem in terms of "relative motion") is simply "real" relative motion between two objects, one of which is really at (relative) rest and one of which is really in (relative) motion.
In terms of SR, it may be convenient for me to assume that when I accelerate a particle, it is the one moving around in circles at high speed rather than me. But such a viewpoint is no more or less valid that the view of the particle, which remains motionless while I (and the building I am in) run circles around it at speeds of .999c.
Now, if you want to say that the earth is "really" orbiting the sun rather than the sun orbiting the earth, then you are suddenly talking about "real" or "absolute" motion, not relative motion in terms of SR.
If the earth is "really" moving with respect to the sun, then (considering only the motion effects on "time") a clock transported from the earth to the sun would run faster. On the other hand, if the sun is "really" orbiting the earth at high speed, then a clock transported from the earth to the sun would run would run slower. According to SR, that would be the case even if we were unable to determine which one was "really" moving relative to the other.
If that were not the case, then we would be unable to synchronize GPS clocks. If we had two clocks, one on the right, and one on the left, and if, no matter which one was put into orbit, the one on the right would always run slower than the one on the left, there would simply be no way to predict or otherwise make sense of the time difference.
Which article, wiki? "You can" what? Tell which one is moving? Of course, you can, the whole bogus "solution" presumes it. Or do you mean "can tell which one is really younger, without knowing which one "stayed home" and which one "turned around" after going off into space? If that's what you mean, how does it explain it?
Yes, the wiki article devotes three paragraphs to the point of view where the shipboard twin does not move, and how even in this point of view, the earthbound twin ages faster.
1. Sure he mentions it, and I already quoted it: "If we allow Ann to return, we've only restated the problem with the names switched." If you can't understand what that means, then just forget it, I don't want to argue about it, it's not important anyway.
I'm pretty sure I understand what that means, and quite possibly better than you. Menton chose not to ti discuss the point of view where the shipboard twin remains stationary, because he wanted to emphasize the standard interpretation of the shipboard twin changing inertial reference frames. This does not mean the shipboard twin comes to a different answer if you take the point of view his reference frame is inertial.
2. I have already told you what I mean by "absolute motion," and it is the same meaning that the wiki problem is giving it when stating the problem. No doubt you have your own *special* definition which you will insist on applying in every situation, regardless of context or the intention of the author. Let me guess: For you, "absolute motion" can ONLY mean (for anyone who ever uses the term) motion which can be compared to something which can be proven to be at absolute rest, such as the ether. Right? That is not how I am using it, and that concept is not one which any author we've seen trying to "explain" this paradox relies on.
Why yes, my special definition. It's so special wikipedia devoted an article to discussing it, because I'm so special. It couldn't be possible that abolute motion is a term of art, with a specific meaning, and that if you use a different meaning and don't state extremely explicitly what that different meaning is supposed to be, you create confusion. It must be my special meaning that is the the issue. That's why none of the articles we have reference use the terminology "absolute motion" in their description of the twin paradox; I'm so special that are scared to use my term and appropriate my specialness. That's why I refused to use terms like "intertial reference frame" in this discussion so many times, it takes away from that definition of absolute motion you described with such clarity, that one of them is "really" moving.
http://en.wikipedia.org/wiki/Absolute_motion
Yeah, I did, did you? Several points can be made about that page:
1. To begin with, he makes it clear that it is not used to solve the problem from a GR standpoint,...
2. He says "We are simply grabbing a result about real gravitational fields from General Relativity," and is then going to apply it to SR. ...
3. Even in GR, gravity is "equivalent to" acceleration, and this guy makes it clear that this explanation does NOT solve the problem: ...Is this explicit "non-solution" (according to this author) the big "explanation" you are wanting me to acknowlege?
Exactly. If you describe the problem from the point of view of Stella being in an inertial frame, you need to bring in an immense gravitational field that breaks the law of convservation of mass-energy to create the observed effects. I mentioned this some 300(?) comments ago. No thinks this is the solution because it breaks the conservation law. However, if you put that aside and simply descibe what happens from the viewpoint of Stella being in an inertial reference frame, Terence still ages more due the effects of the pseudo-gravitational field that the ship's acceleration creates. The Equivalence Principle link describes in moderate detail why this gravitational field has this effect.
After reading your posts, I'm still not clear about what you think is being said in these "explanations." Let me just ask you: Do you still claim that the same twin (the one who happens to be on the rocket ship) will always be younger, regardless of whether you treat the ship or the earth as the thing that is moving?
Not only do I think that, both the wiki page and the Equivalence Principle explanation page explain it this way. It is not considered the solution for other reasons, but the answer from that point of view with regard to the twin paradox is the same: the shipboard twin ages less, the earthbound ages more.
One Brow said: "In different points of view, either can be younger than the other. There is no "really is".
Then why do you insist that pages of bogus explanations which purport to prove that one twin REALLY IS younger are reliable, I wonder?
Because that comment was about Pat and Chris, neither of whom ever changes their inertial reference frame, and not about the twin paradox.
You could have saved a lot of governments many billions of dollars if you'd only informed them of this before they went around buildin all kinda "particle accelerators," ya know? Them fools actually think they are accelerating particles to, like, .999c.
From our point of view, they get close to .999c (or whatever it is) and the difference between them and light is c. From the point of view of the particle, the difference between it's speed and the speed of light will be c.
As shown above, she accelerates either way. This is just a (bogus) way to create a scenario where she "thinks" she isn't moving, and one which does NOT purport to solve the twin paradox. The guy made it very clear, on his first page, what the real solution is: There is no paradox because one, and only one, is moving and the other can't be construed as moving.
Due to conservation of energy, not to the relativistic components of the problem.
Which link? Which author? I think you mean the same one I am quoting, who says a guy will age 14 years in zero time.
Let me just ask you: Do you think this is what would "really" happen?
Really happen from which point view?
I mean, really? If someone happens to be observing me in such a way that I seem to be aging 14 years instantaneously, will it happen to me?
In your point of view? No. In their point ov view, yes.
Suppose one person saw me aging 14 years, and another saw me aging 50 years in the same instant?
You'll have to define "same instant" and the conditions under which that happens a *lot* more carefully.
Are you proposing a triplet situation, where Stella and Stan leave the earth at different velocities relative to earth, to so Stella (going faster raltive to to earth) sees you age much less on the outbound jouney than Stan, and then they both see age at a turn around? Stella and Stan will be nowhere close to each other at turnaround, and the notion of "simultaneous" will mean very little in that case. However, because of the added distance involved, you age more in the frame of reference where Stella is inertial than you do in teh frame of reference where Stan is inertial. Because these are different reference frames, it makes no sense to talk about them having a combined effect.
Would I do both, and thereby age a total of 64 years instantly, or what? The whole problem with some of these SR analyses, and the theory in general, is that it can't seem to separate false appearances from reality.
Maybe the problem is you are so wedded to the notion of a "true' reality you are not seeing what the analyses are saying?
Or, as I said originally, can't seem to separate mathematical "truth" from practical truth.
All the mathematical "truths" lead to the same answer anyhow.
I said: "As shown above, she accelerates either way. This is just a (bogus) way to create a scenario where she "thinks" she isn't moving, and one which does NOT purport to solve the twin paradox."
Let me elaborate on this point, using the author's own words, because I have a feeling you will not see the point without it being explicitly brought to your attention.
1. Is Stella "really" turning around in this "analysis" and only think that she is remaing motionless, or
2. Is she really remaining motionless?
If we adopt the framework where mass-energy is conserved, we need to adopt viewpoint 1. This does not mean viewpoint 2 gives a different answer, we just don't like the method for other reasons.
Notice that she is only "assuming" a pseudo-force when, in fact, she has turned on her thrusters and, as it says, "turns-around."
No argument there. Do you think the answer would change if, by some miracle, this was not an assumption bt a real state of events?
If we start with the premise that all motion is relative (which it is) then it is an obvious oxymoron to speak of absolute motion. But, within the confines of relative motion, some motion is known to be "real" or "absolute" as between the specific objects being compared.
The term you are looking for is "inertial". Any intertial motion is equally "real".
"Absolute" motion (as I am using it, and as wiki is using in setting up the paradox problem in terms of "relative motion") is simply "real" relative motion between two objects, one of which is really at (relative) rest and one of which is really in (relative) motion.
Wiki doesn't use the term, because the term has a real meaning that you are ignoring. What you are really referring to is inertial motion. We see the car as "really" moving because the car accelerated, the alternative of the earth aceleratiing violates mass-energy conservation.
If the earth is "really" moving with respect to the sun, then (considering only the motion effects on "time") a clock transported from the earth to the sun would run faster. On the other hand, if the sun is "really" orbiting the earth at high speed, then a clock transported from the earth to the sun would run would run slower. According to SR, that would be the case even if we were unable to determine which one was "really" moving relative to the other.
Because the would be moving in and out of gravity wells of different sizes, I suspect the time effects of GR would dominate those of SR.
If that were not the case, then we would be unable to synchronize GPS clocks. If we had two clocks, one on the right, and one on the left, and if, no matter which one was put into orbit, the one on the right would always run slower than the one on the left, there would simply be no way to predict or otherwise make sense of the time difference.
As long as you can predict the difference ahead of time, you can adjust for it with a very simple algoritm.
Yes, "absolute motion" is, or can be, a term of art. However, physics is not the only "art" which uses the term, and not all "arts" use it the same:
"(navigation) Motion relative to a point fixed on the earth's surface or to an apparently fixed celestial point.
http://www.answers.com/topic/absolute-motion
I can't believe that you can't see the implications of your own statements. No matter what the case, all these solutions presume that only the starship is "accelerating" and therefore "changing frames of reference."
You never directly responded to this post, that I recall:
1. He asks: "Or can Stella declare that the Earth did the travelling, so Terence is the younger?"
I said: "He is implicitly saying that IF the earth was moving, then Tereance (earth twin) WOULD be younger. He simply denies that the earth was (or could properly be considered to be) the thing which was "really" moving."
Do you deny that's what he's implying? Yes or no?
2. He says: "Stella's frame is not inertial while she is accelerating. And this is observationally detectable: Stella had to fire her thrusters midway through her trip; Terence did nothing of the sort. The Ming vase she had borrowed from Terence fell over and cracked. She struggled to maintain her balance, like the crew of Star Trek. In short, she felt the acceleration, while Terence felt nothing."
Do you deny the reason's the guy gives for saying that, in this case, the earth can't be considered to be the thing "really" moving?" Yes or no?
3. He says: "Terence sits at home on Earth. Stella flies off in a spaceship at nearly the speed of light, turns around after a while, thrusters blazing, and returns."
Does the problem he is addressing, in every case, including the "EP analysis non-solution," expressly assuming that Stella is the one who is really travelling (whatever her personal assumptions or delusions may be)? Yes or no?
The equivalence principle, as I understand it, says that gravitation cannot be "asolutely" distinguished from fictitious intertial forces. The whole problem is about age difference due to speed, not gravitation. The guy himself says it does not address or "solve" the paradox problem, yet you insist this will make Stella younger EVEN if she never moved while the earth moved away from her, then returned. Heh.
If you are found dead in your bed of a heart attack, my conclusion would be: You are dead.
If it is found that you have been brutally murdered, dismembered, then cannibalized by Jeff Dahlmer, my conclusion would be: You are dead.
Since I reach the same conclusion in each case, then the assumptions my conclusions are founded upon must be identical, that the idea?
Let me take it a step further: Since you are dead due to the dastardly deeds of Dalhmer, then anyone else who is dead must be dead for the same reasons. Why? Because the same ultimate conclusion results: You are dead, and they are dead. That the idea?
One Brow said: Yes, the wiki article devotes three paragraphs to the point of view where the shipboard twin does not move, and how even in this point of view, the earthbound twin ages faster."
Really? Can you quote them, and/or the relevant passages therefrom which say that if the starship twin is deemed to be motionless while assuming that the earth twin "travels and returns" the earth twin will still be older? I don't see that anywhere. What I do see is the exact opposite implication, and I have quoted many of the passages which say this.
Relativity is a heaven for those who like to use fallacious equivocation to "prove" their points. By the same token, it is a magnet for the credulous who cannot detect this type of fallacy when they encounter it.
I said: "Since I reach the same conclusion in each case, then the assumptions my conclusions are founded upon must be identical, that the idea?"
Or how about this: You brutally murder, dismember, and canibalize Jeff Dalhmer. My conclusion: You are dead. It's like this, see?: Someone is dead (younger) here, and it's always you, regardless of who butchers who.
And, how could I possibly reach that conclusion? Well, somehow, lemme see....oh, yeah, because you died of a heart attack and you are dead, remember?
Notice that she is only "assuming" a pseudo-force when, in fact, she has turned on her thrusters and, as it says, "turns-around."
No argument there. Do you think the answer would change if, by some miracle, this was not an assumption bt a real state of events?
Sure it would. For one thing, she would never turn around, she would just sit there forever, or at least until her thrusters ran out of power. Then there would be no thrust to cancel, and she would go flying off in the direction of the gravitational field. The whole problem assumes that she leaves, turns around, and returns. That is how we know her sense of "gravitation" is delusional.
The guy is only say that she can "assume" that all the shaking, etc., she experiences at turn-around is due to gravity (but it aint). But either way, she can't deny the acceleration. Either way, she experinces the shaking, hence acceleration, hence a frame shift. Without the frameshift, you get an entirely different "answer" to the question of "who is younger?"
But again, both heart attacks and dismemberment can cause death. We don't use a dismemberment hypothesis to "explain" a death due to heart attack. Gravitation can cause it's own, independent, time dilation, which is entirely different than that caused by speed, but that is entirely irrevelant to this problem. It is simply "cheating" and "equivocating" to use one to "explain" the other.
The guy is only say that she can "assume" that all the shaking, etc., she experiences at turn-around is due to gravity (but it aint). Furthermore, either way, she experinces the shaking, hence acceleration, hence a frame shift.
I said: "That is how we know her sense of "gravitation" is delusional." And that is precisely where the fallacious equivocation of this author comes in. He starts off with this statement: "We'll pick a frame of reference in which Stella is at rest the whole time!" He even uses an exclamation point to emphasize this false claim. He knows damn well that, in the explanation he is about to give, she really is moving, not at rest. But before giving you her delusional assumptions, he tries to put you in a state of mind where you falsely assume that he is telling you she is "at rest the whole time!"
He is NOT telling you that, all said and done. And he knows it. But some reading it (you, perhaps?) wouldn't realize that, after he set you up to expect otherwise.
If you can comprehend that 1 + 2 = 2 + 1, then you should easily be able to see that, in all these explanations, wiki or otherwise, if the earth twin is presumed to be the one which heads off, turns around, then returns, then THAT twin will be younger.
It's not a large step from there to realize that the one who is "really" moving is the one who will really be younger (which is precisely what SR posits to begin with, i.e., as speed increases, time slows down).
I said: "It's not a large step from there to realize that the one who is "really" moving is the one who will really be younger (which is precisely what SR posits to begin with, i.e., as speed increases, time slows down)."
Apparently you are not aware of this aspect of special relativity, or, if you are, deny it, one or the other. Just in case you think I am making it up, here's a quote from one (of millions probably) that authoritatively makes this point:
"One of the fundamental results of Albert Einstein's special theory of relativity is a phenomenon known as time dilation. Simply put, this result states that time moves more slowly for a moving object than it does for an object at rest."
http://physics.suite101.com/article.cfm/the_twin_paradox
By the way, this same website states the real "paradox" just as I have consistently stated it to be, and it also shows why it is not really a paradox (i.e., because, contrary to the basic premises of SR, it is assumed in these "solutions" that "real motion" is involved):
"Special relativity claims that all inertial frames are equally valid - that there can be no "preferred" frame of reference. In the story of the twins, though, this doesn't seem to hold up. The twin in the spaceship is said to be "moving" while the other is "stationary." <--- it is the "equally valid" claim that creates the paradox.
The (non) solution?: "The most important explanation for the twin paradox came from French physicist Paul Langevin in 1911...This explanation revolves around the idea of acceleration...As a result of the acceleration, therefore, the twin in space does indeed possess motion in a relative sense to the non-accelerating twin on Earth, and thus is effected by the time dilation of special relativity."
See there where it says that the twin in space "DOES INDEED" possess motion? That's just what I have been calling "real" or "absolute" motion--all detected by acceleration.
Again, just in case you might overlook the implications, see where it says "thus?"
As a result of the acceleration, therefore, the twin in space does indeed possess motion in a relative sense to the non-accelerating twin on Earth, and THUS is effected by the time dilation of special relativity."
It is the moving twin who is affected, whichever one that may be, not the one who is presumed to be "motionless."
One Brow said: "the wiki solution does not require absolute motion."
Even within the realm of SR, accelerated motion is deemed to be "absolute," not relative. I'm not convinced of this, but that's irrelevant. So, I think that, even within the confines of SR, the wiki examples explicitly rely on absolute motion. And, as I said, despite trying to create impressions to the contrary, the article does NOT show how an "absolute effect" (aging) can result from "relative motion." They must resort to absolute motion (acceleration).
Yes, "absolute motion" is, or can be, a term of art. However, physics is not the only "art" which uses the term, and not all "arts" use it the same:
We are having a physics discussion, last I checked.
I can't believe that you can't see the implications of your own statements. No matter what the case, all these solutions presume that only the starship is "accelerating" and therefore "changing frames of reference."
Yes, I have said that, and repeated that. They make this presumption because of conservation of mass-enery, not because of anyting internal to SR/GR.
Do you deny that's what he's implying? Yes or no?
No.
Do you deny the reason's the guy gives for saying that, in this case, the earth can't be considered to be the thing "really" moving?" Yes or no?
Yes, that is the reason he gives.
Does the problem he is addressing, in every case, including the "EP analysis non-solution," expressly assuming that Stella is the one who is really travelling (whatever her personal assumptions or delusions may be)? Yes or no?
Absolutely, the conservation of mass-energy demands that this is the correct framework.
Since I reach the same conclusion in each case, then the assumptions my conclusions are founded upon must be identical, that the idea?
In the two cases, you will find different lines of evidence between a heart attack and a murder. I am talking about a case where there is no difference in the evidence.
One Brow said: Yes, the wiki article devotes three paragraphs to the point of view where the shipboard twin does not move, and how even in this point of view, the earthbound twin ages faster."
Really? Can you quote them, and/or the relevant passages therefrom which say that if the starship twin is deemed to be motionless while assuming that the earth twin "travels and returns" the earth twin will still be older? I don't see that anywhere. What I do see is the exact opposite implication, and I have quoted many of the passages which say this.
You have interpreted passages as saying they reference who is "really" moving, but the passages do not mention this concept as being the reason one ages and the other does not.
Relativity is a heaven for those who like to use fallacious equivocation to "prove" their points. By the same token, it is a magnet for the credulous who cannot detect this type of fallacy when they encounter it.
*chortle*
aintnuthin: Notice that she is only "assuming" a pseudo-force when, in fact, she has turned on her thrusters and, as it says, "turns-around."
One Brow: No argument there. Do you think the answer would change if, by some miracle, this was not an assumption bt a real state of events?
aintnuthin: Sure it would.
You are incorrect.
However, maybe I was unclear in what I was explaining, so let me draw a clearer picture.
First, let's remove any notion of Stella's experiencing turbulence from her engines thrusting, because it does not affect the problem. She still feels the acceleration, of course. Let's also make it a windowless environment, where Stella waits while her rocket fires according to a pre-programmed schedule. The answers are all the same, of course, Stella ages less, Stella is really moving..
Now, let's look at Astro and Eartha. Astro climbs into a box much like Stellas. However, when Astro's sequenmce starts, a massive gravitational force pulls the planet, and Eartha with it. The engines in Astro's rocket keep him from being dragged along. To an observer far away from the planet, but in the same inertial frame that Astro adn Eartha share, Astro continues to stay in that inertial frame as his rockets compensate exactly for the gravity that moves Eartha and the planet away from, and then back to Astro. What Astro experiences will feel exactly like Stella experiences, and that also applies to Eartha and Terence. Who is "really" moving, Eartha or Astro? Who ages less, Eartha or Astro? My answer is in the next comment.
Here's one more, and I'm honestly not sure about this one: we can set up Rigel and Gaia to sorrespond to Astro and Eartha, except Rigel's ship does not have rockets or thrusters, it has an anti-gravity field that makes it immune to the effects of the gravity moving Gaia's planet. Gaia's experience will be the same as Terence or Eartha, but what Rigel experiences will not match Stella and Astro. Who is "really" moving, Rigel or Gaia? Who ages less, Rigel or Gaia? My guess in in the next comment.
The guy is only say that she can "assume" that all the shaking, etc., she experiences at turn-around is due to gravity (but it aint). Furthermore, either way, she experinces the shaking, hence acceleration, hence a frame shift.
Here, I almost thought you had it.
It's not a large step from there to realize that the one who is "really" moving is the one who will really be younger (which is precisely what SR posits to begin with, i.e., as speed increases, time slows down).
Then here, I realized you did not.
Apparently you are not aware of this aspect of special relativity, or, if you are, deny it, one or the other. Just in case you think I am making it up, here's a quote from one (of millions probably) that authoritatively makes this point:
...
http://physics.suite101.com/article.cfm/the_twin_paradox
He is promoting Langevin's point of view, which Langevin hoped to use to justify absolute motion. I'm not surprised you took to it.
I'm not denying anything, BTW. You can probably tell that from all the times I've said, 'Yes, and this is why they say that'.
By the way, this same website states the real "paradox" just as I have consistently stated it to be, and it also shows why it is not really a paradox (i.e., because, contrary to the basic premises of SR, it is assumed in these "solutions" that "real motion" is involved):
That was Langevin's view in 1911. However, you don't need that assumption in the situation, the answers are the same with or without it.
Even within the realm of SR, accelerated motion is deemed to be "absolute," not relative. I'm not convinced of this, but that's irrelevant.
Accelration can be deemed observable, in that it refers to a measurable difference between intertial frames. But even then, the amount of acceleration seen will vary from observer to observer. Given Andrew and Betty in the same intertial environment, Chris moving at .9c compared to them. Andrew accelerates to what Betty sees as .5c in the opposite direction from Chris' relative motion. Chis will see less than .1c of acceleration in that direction. So I don't think you can call acceleration "absolute".
Answer: Under any reasonable interpretation (that is, one that conforms to the conservation of energy), Eartha is moving. However, Astro will age less.
Gaia is really moving (again under conservation of energy).
Guess: Gaia and Rigel will have aged the same amount.
One Brow said: "He is promoting Langevin's point of view, which Langevin hoped to use to justify absolute motion. I'm not surprised you took to it."
Langevin? What the hell does he have to do with the point you addressed this comment to? Can't you even see the view being presented (which is Einstein's, not Langevin's) has NOTHING to do with acceleration?
To restate quote, he said: "One of the fundamental results of Albert Einstein's special theory of relativity is a phenomenon known as time dilation. Simply put, this result states that time moves more slowly for a moving object than it does for an object at rest."
He is talking about rest versus motion (whether accelerated or not). "As Einstein put it in his original paper: If two clocks are synchronized while in close proximity to each other, then one of them is taken away for some time, perhaps on a journey, then they are brought together, they will no longer be in tune with each other. The clock which has been in motion will have recorded time more slowly than the clock at rest."
Look at that last sentence from Einstein once again, and see it you can glean any clue from it about which twin would be younger if the earth moved away and returned, eh?
Eric, you are so utterly confused about this whole topic that I don't even know how to proceed. I say: My speedometer coulb be off because it calibrates distance incorrectly. You say: "WRONG!!! It could be off because your clock is incorrect!!" Do you even see the problem with the response?
The twin paradox problem is about time dilation effects DUE TO MOTION, not gravity. Dreaming up all kinds of scenarios where gravity, not time, dilates time have NOTHING to do with it. NOTHING. As I said, one does not use a heart attack hypothesis to explain dismemberment, even though each can lead to death.
One Brow said: "You have interpreted passages as saying they reference who is "really" moving, but the passages do not mention this concept as being the reason one ages and the other does not."
Can you quote a passage where wiki says what you claim it says, or not?
This is about the fifth time you have made flat assertions (raw, unsupported conclusions) about what the wiki article says. However, you never say why you reach your conclusions, and I sure can't see any language in wiki to support it.
Kinda like this here comment:
The twin paradox problem is about time dilation effects DUE TO MOTION, not gravity. Dreaming up all kinds of scenarios where gravity, not time, dilates time have NOTHING to do with it. NOTHING. As I said, one does not use a heart attack hypothesis to explain dismemberment, even though each can lead to death.
In each of the scenarios I posed, there was relative motion. Answer the questions. If you're not sure, do some research, or ask a couple of people you trust. Don't come back with how I don't understand this or that when I keep confirming the facts of what you tell me and explaining why your interpretation is wrong, if you expect me to take you seriously.
The explanation is in the three paragraphs on the general relativity solution. ONe particular quote:
"(It should be emphasized that according to Einstein's explanation, this gravitational field is just as "real" as any other field, but in modern interpretation it is only perceptual because it is caused by the traveling twin's acceleration)."
Einstien interpreted it as a real field (and as a consequence, that earth twin was not in an inertial framework), the modern interpretation is that it is not, but either way the anwer was the same. Stella ages less, so does Astro. But it is Stella and Eartha that are "really" moving. Do you agree or not?
Edit: "that earth twin was not in an inertial framework from the viewpoint of someone outside situation in an inertial framework".
One Brow said: "He is promoting Langevin's point of view, which Langevin hoped to use to justify absolute motion. I'm not surprised you took to it."
Keep in mind that the wiki article purports (1) to be addressing a problem in special (not general) relativity, (2) involves the issue as it relates to "high speed," and (3) that the problem itself assumes only one of the two twins "makes a journey" (is really moving). It says:
"In physics, the twin paradox is a thought experiment in special relativity, in which a twin who makes a journey into space in a high-speed rocket will return home to find he has aged less than his identical twin who stayed on Earth."
You act as though you are relying on wiki and as though there is something wrong with "Langevins' point of view." But wiki itself says:
"Starting with Paul Langevin in 1911, there have been numerous explanations of this paradox, all based upon there being no contradiction because there is no symmetry — only one twin has undergone acceleration and deceleration, thus differentiating the two cases."
It does go on to say: "One version of the asymmetry argument made by Max von Laue in 1913 is that the traveling twin uses two inertial frames: one on the way up and the other on the way down. So switching frames is the cause of the difference, not acceleration per se." As I said a long time ago, acceleration is not the per se cause of the age difference (speed alone is, accelerated or not). It is only the method by which "absolute motion" is detected in the "numerous explanations" based on acceleration beginning with Langevin.
Within the context of SR, one cannot detect "two inertial frames" for one twin without resort to acceleration either, so there is no real difference between that view and Langevin's view.
Finally, it says: "Other explanations account for the effects of acceleration. Einstein, Born and Møller invoked gravitational time dilation to explain the aging based upon the effects of acceleration." All the authors I've read, including the one you wish to rely on so heavily, say that GR is not necessary to address the problem. SR is not GR, and the issue is about the dilation effects of "highspeed," not gravity, so GR is irrelevant. It can be used, but, even then, as I have repeatedly noted, the whole problem presupposes a "travelling twin" (and his viewpoint) which has to be distinguished from the viewpoint of the "stay at home" twin. If the earth was moving, the earth twin would be younger even in the GR analysis. The problem with the GR analysis is that it doesn't directly address the "highspeed" issues of SR which the problem sets out to resolve.
I have just quoted Einstein as giving an early explanation of the twin paradox with no allusion to GR. He says it is the clock which "moves," whether on a "journey" or not, which will record time more slowly.
One Brow said: "In each of the scenarios I posed, there was relative motion. Answer the questions."
See my post above, the question isn't whether your scenarios contain "relative motion." One problem is that they also incorporate gravitional time dilation and therefore conflate the two and don't address the specific problem posed. There are other problems with these "solutions" too, but they are not at issue here. Im every measurment of distance, there is both a time and a distance factor. That doesn't mean that time is distance.
I can create an arbitrary scenario where there is substantial time dilation without ANY motion (so long as there is gravity) Likewise, I can create one where there is substantial time dilation without ANY gravity (so long as there is motion). The twin paradox, as posed, has NOTHING to do with gravity. It has to do with SR, not GR.
One Brow said: " But it is Stella and Eartha that are "really" moving. Do you agree or not?"
I haven't even looked at these, because they are irrelevant for reasons stated in my prior posts. If your simply asking me if a scenario can be created where time dilation can occur either (1) with no motion, or (2) due to some combined effects of both motion and gravity, then, yes, I agree with that, as I've already said.
One Brow said: "The explanation is in the three paragraphs on the general relativity solution."
I have quoted this section several times myself. It does NOT say that the non-travelling twin would not age IF it were the one travelling. It says otherwise, by strict implication. The whole analsyis it gives is for the "travelling twin" and is for the "turn-around." If it were the earth twin travelling and turning around, then he would be younger. Do you really disagree?
Wiki: "The issue in the general relativity solution is how the traveling twin perceives the situation during the acceleration for the turn-around."
I said: "Sure it would," and then said why it would.
You said: "You are incorrect" without saying why. Your "clarfication" simply shows you completely miss the point and misapprehend the problem. You end up saying: "The answers are all the same, of course, Stella ages less, Stella is really moving."
If Stella is "really moving," as you say, then any delusions she creates for herself in a windowless environment are simply irrelevant--which was my point to begin with. She is "really moving." So how, pray-tell, am I "incorrect?"
Your attempt to then create novel, but irrelevant, scenarios, the facts of which are substantially different from the EXPRESS facts of the twin paradox puzzle, do not make me "incorrect," either, needless to say.
If I ask a guy what kind of car is behind me, and he (correctly) says it is a "red Ford," then he has answered the question I asked. It would merely be pure non sequitur, which would in no way address my question or undermine his answer, if you piped up with: "But it wouldn't be a red Ford if it was a red Oldsmobile."
Eric, it seems to me that, among other things, you are prone to give "answers" to questions other than the one being asked. One then wonders, of course, if you even understand the question.
Suppose I ask you: How old is Charles Barkley? Suppose you answer with a vivid description about the beauty of the state of Alabama, and then tell me Barkley grew up in Alabama.
So, I ask: What does that have to do with what I asked you? You say: "You asked about Charles Barkley, didn't you?"
"One Brow said: "He is promoting Langevin's point of view, which Langevin hoped to use to justify absolute motion. I'm not surprised you took to it."
"Hoped to use to justify absolute motion?" How ya figure? Not this author, who expressly says:
"In the end, then, if Langevin's view is accepted (as it generally is), this story is not so much a paradox within special relativity, but in some ways a confirmation, as it helps to exemplify some of the fundamental features of the theory using a very accessible thought experiment."
wiki: "It should be stressed that neither Einstein nor Langevin considered such results to be literally paradoxical: Einstein only called it "peculiar" while Langevin presented it as evidence for absolute motion....In other words, neither Einstein nor Langevin saw the story of the twins as constituting a challenge to the self-consistency of relativistic physics....Langevin explained the different aging rates as follows: “Only the traveler has undergone an acceleration that changed the direction of his velocity”. According to Langevin, acceleration is here "absolute", in the sense that it is the cause of the asymmetry (and not of the aging itself)."
Notice that Langevin says the acceleration, NOT the uniform motion before and after acceleration, is "absolute". Notice also that it explicitly says (as I have) that acceleration does not cause the aging. Although he created the "twin paradox" in the "twin form, it was simply a variation of Einstein's own where Langevin substituted "twin" for "clock."
I quoted an author as saying: "
One of the fundamental results of Albert Einstein's special theory of relativity is a phenomenon known as time dilation. Simply put, this result states that time moves more slowly for a moving object than it does for an object at rest.
One Brow said: ""One Brow said: "He is promoting Langevin's point of view..."
Let me just clear this up, once and for all. Is there ANY respectable author you know of who DENIES the validity of what the author I quoted says?
[Please note: This is an entirely different topic I am turning to. It has nothing to do (at least not specifically and directly) with the dispute about whether the earth twin would be younger if the "twin paradox" posited that the earth twin was the one moving].
Among other things, Eric, I think you want to simultaneously (1) assert that there is no real paradox, and (2) assert that the very claims which do lead to a true paradox are also true. But you can't have it both ways.
I have just about given up about all hope that you will ever understand what I'm gunna say, but, like, who knows, eh? Remember, wiki purports to answer this question: "How can an absolute effect (one twin really does age less) result from a relative motion? Hence it is called a paradox." My answer: It can't. Yours is, apparently, "It can."
1. First consider these claims from a wiki article on "time dilation:"
"In the case that the observers are in relative uniform motion, and far away from any gravitational mass, the point of view of each will be that the other's (moving) clock is ticking at a slower rate than the local clock. The faster the relative velocity, the more is the rate of time dilation." So,
1. Each "sees" his own clock as correct, and
2. Each "sees" the other's clock as "ticking at a slower rate."
Now, notice, so far, the statements are ONLY about what each "sees," without regard for which, if any, of these observations are correct. But, if I see my clock as being "correct" in any absolute sense, then I must see yours as being incorrect, even if it is "correct" for you, from your viewpoint. I can't, from my viewpoint, or any other viewpoint, say that your viewpoint and my viewpoint are both "correct" except in a completely relative way.
If I see a color as green, and you see it as yellow, it is fair to say that it is green FOR ME, and it is yellow FOR YOU. But it would be a logical contradiction to say that the object is question "really is" both green and yellow from an objective standpoint. You either take a subjective (relative) definition of what is "correct" or an objective definition of what is "correct", but you simply can't take both viewpoints simultaneously.
2. Wiki acknowledges this contradiction (from an objective viewpoint), and shows how the logical inconsistency is resolved in SR:
"It is a natural and legitimate question to ask how, in detail, special relativity can be self-consistent if clock A is time-dilated with respect to clock B and clock B is also time-dilated with respect to clock A. It is by challenging the assumptions built into the common notion of simultaneity that logical consistency can be restored....Because the pairs of putatively simultaneous moments are identified differently by different observers (as illustrated in the twin paradox article), each can treat the other clock as being the slow one without relativity being self-contradictory"
So, let's analyze this. There is a lot of fancy-ass talk of the "relativity of simultaneity," which can be confusing. This, they say, is just like the notion that if we are facing each other, your right is my left, and vice versa. But it all really boils down to this: It is not contradictory to say that each one "sees" things differently, even if it would be contradictory that both are absolutely correct. Appearances can be relative, in which case they cannot be treated as absolute. I am "correct" when I say, when facing north, that east is to my right, and that west is to my left. You are "equally correct" when you, when facing south, have west to your right and east to your left. What would be wrong would be to say, in some absolute sense, that "east is to the right." OK, I get it, so far.
Continued in next post...
So, then, going back to point (1), above, we could say that each is correct about his own clock being correct (my right is my right, and your right is your right). But it would be WRONG to say that, because I see my own clock is correct, then the way I see your clock is also correct. (I see your left as my right, but your right is still your right, not mine).
We could even reverse that: I could say that the way I see your clock is correct, and that the way I see my own clock is therefore incorrect, and you could do the same. But what I can't say, without logical contradiction, is that the way I see my own clock is correct AND the way I see your clock is also objectively correct. If my clock is correct (for me), then yours must be wrong (for me).
There is no logical contradiction in saying that I see your clock as running 10 times slower than mine and that you see my clock as running 10 times slower than yours (anymore than it is to say east is on my right and you say west in on your right). Or, as wiki put it: "...each can treat the other clock as being the slow one without relativity being self-contradictory." Important to note: Is says that each can "treat" the other's clock as being slow without contradiction. It does NOT say that each can say that the other's clock "really is" slow without contradiction.
That's because it IS a contradiction to say that east is west. Again, I can't simultaneously claim that the way I see my clock is correct (east in on my right) AND that the way I see your clock is also correct (1.e., that east is also on YOUR right, which it aint). Do you understand that so far? Do you agree that I can't claim that both my clock and your clock are objectively correct without contradiction?
If not, please tell me why. If you do agree, then I will continue with this post later.
P.S. Before answering, consider this statement again: "Because the pairs of putatively simultaneous moments are identified differently by different observers (as illustrated in the twin paradox article), each can treat the other clock as being the slow one without relativity being self-contradictory."
Second question: What do they mean here by the words "can treat?" Does it mean (1) that both are slow; (2) neither is slow, but each is falsely "treating" the other as being so; or (3) that one actually is slower than the other, and it is therefore incorrect to say that either (1) or (2) is correct. If you pick (3), then somebody is "wrong" in the way they are "treating" the other's clock, and the other is right. Remember, the "solution" to the twin paradox claims that one REALLY IS younger.
One Brow said: "In each of the scenarios I posed, there was relative motion. Answer the questions."
See my post above, the question isn't whether your scenarios contain "relative motion." One problem is that they also incorporate gravitional time dilation and therefore conflate the two and don't address the specific problem posed.
Your specific point, that you keep coming back to over and over, is that in order to answer the twin paradox, the notion that Stella is "really" moving is important. So, with Astro and Eartha I created a scenario where the relativistic conditions are identical, but the twin who is not on the ship is "really" moving. That is the specific problem posed by you, as far as I can tell: is the resolution a the matter that one person is "really" moving, or is the resolution strictly from the relative movements. My understanding is the latter. I am asking you, in the Astro/Eartha scenario, to stand by your claim (saying Eartha will age less) or modify your claim to change the notion of who is "really" moving into something else (say, a change in in the experienced inertial frames), noting that this means the solution actually is strictly within the bounds of relativity and does not need the extra notion of "really" moving tacked onto it. If you simply refuse to address this separation, I'm going to assume you don't believe your own claims or can't say what you mean intelligently enough to be understandable.
There are other problems with these "solutions" too, but they are not at issue here. Im every measurment of distance, there is both a time and a distance factor. That doesn't mean that time is distance.
I agree. The reason time is a dimension that has distance is a manner very much like space has distance is not derived from there being a time and distance factor to various measurements.
Within the context of SR, one cannot detect "two inertial frames" for one twin without resort to acceleration either, so there is no real difference between that view and Langevin's view.
I agree.
If the earth was moving, the earth twin would be younger even in the GR analysis.
Moving in what manner? With a big rocket attached to the earth? That is not the same thing as analyzing the standard scenario from the point of view that Stella is stationary.
The problem with the GR analysis is that it doesn't directly address the "highspeed" issues of SR which the problem sets out to resolve.
The GR analysis does incorporate the high speeds as well as other effects.
I have just quoted Einstein as giving an early explanation of the twin paradox with no allusion to GR. He says it is the clock which "moves," whether on a "journey" or not, which will record time more slowly.
Thtis the usual way of saying the clock moves through less time.
If it were the earth twin travelling and turning around, then he would be younger. Do you really disagree?
Again, if you mean traveling by a big rocket attached to theplanet, or course I agree.
I said: "Sure it would," and then said why it would.
You said: "You are incorrect" without saying why.
I went into three paragraphs to explain why your answer was incorrect. You have a curious definition of "not saying why".
"aintnuthin: Notice that she is only "assuming" a pseudo-force when, in fact, she has turned on her thrusters and, as it says, "turns-around."
One Brow: No argument there. Do you think the answer would change if, by some miracle, this was not an assumption bt a real state of events?
aintnuthin: Sure it would. "
You made a claim that the resolution to the paradox would be different if Stella's perception of gravitational forces was correct. You were wrong, and I think you realize the Astro/Eartha scenario says that if Stella perceptions of a gravitational field are correct, the answer is the same. The answer does not depend on Stella's perception being a pseudo-graviational field, because Astro's experience is a real field. The answer does not depend on Stella really moving, because Astro doesnot really move, but still ages less. The answer only depends on the relative movements of Terence and Stella (or Astro and Eartha) and the changes in inertia they can see.
Your attempt to then create novel, but irrelevant, scenarios, the facts of which are substantially different from the EXPRESS facts of the twin paradox puzzle, do not make me "incorrect," either, needless to say.
When I proposed a difference to the standard scenario, you said it would change the answer. I explained why it would not change the answer. This was diectly related to your affirmation that the answer changes if Stella perception is not of a pseudo-gravitational force, but a real one. That affirmation was and is wrong. Maybe you misunderstood the sentence, because the next paragraph seems to describe a constant gravitational field, which is *not* the same thing as analyzing the twin paradox from Stella's viewpoint, for her the (pseudo)gravitational fields are not constant, they are turned on and off and get reversed in direction.
Eric, it seems to me that, among other things, you are prone to give "answers" to questions other than the one being asked. One then wonders, of course, if you even understand the question.
Perhaps the issue is that you don't understand this well enough to ask the question you mean to ask.
Let me just clear this up, once and for all. Is there ANY respectable author you know of who DENIES the validity of what the author I quoted says?
None that I can think of. It all looked pretty reasonable to me.
Among other things, Eric, I think you want to simultaneously (1) assert that there is no real paradox, and (2) assert that the very claims which do lead to a true paradox are also true. But you can't have it both ways.
How I would have it is not relevant.
If I see a color as green, and you see it as yellow, it is fair to say that it is green FOR ME, and it is yellow FOR YOU. But it would be a logical contradiction to say that the object is question "really is" both green and yellow from an objective standpoint. You either take a subjective (relative) definition of what is "correct" or an objective definition of what is "correct", but you simply can't take both viewpoints simultaneously.
In this example, we have an objective means of verifying the color of the apple (the combined frequencies of light that bounce off of it), and ways to verify the accuracy of our sensory apparatus (perhaps I have a specific sort color-bindness resulting from defective eye pigments). I am not interjecting this randomly, this is important to the differences between the scenarios.
So, let's analyze this. There is a lot of fancy-ass talk of the "relativity of simultaneity," which can be confusing.
You want confusing, try the ladder paradox.
This, they say, is just like the notion that if we are facing each other, your right is my left, and vice versa. But it all really boils down to this: It is not contradictory to say that each one "sees" things differently, even if it would be contradictory that both are absolutely correct. Appearances can be relative, in which case they cannot be treated as absolute.
Which then begs the question if there is an absolute.
Again, I can't simultaneously claim that the way I see my clock is correct (east in on my right) AND that the way I see your clock is also correct (1.e., that east is also on YOUR right, which it aint). Do you understand that so far? Do you agree that I can't claim that both my clock and your clock are objectively correct without contradiction?
If not, please tell me why. If you do agree, then I will continue with this post later.
I agree, but I will go further: you can't claim either clock is objectively correct, period. You can arbitrarily pick either or neither clock to be the "correct" one, as there are an infinite number of reference frames where neither is correct.. So, neither clock is objectively correct, but they are equally correct.
Second question: What do they mean here by the words "can treat?" Does it mean (1) that both are slow; (2) neither is slow, but each is falsely "treating" the other as being so; or (3) that one actually is slower than the other, and it is therefore incorrect to say that either (1) or (2) is correct. If you pick (3), then somebody is "wrong" in the way they are "treating" the other's clock, and the other is right. Remember, the "solution" to the twin paradox claims that one REALLY IS younger.
(2) is the best answer. Neither clock is slower within it's own reference frame. The real issue is that there is no absolute answer.
One Brow said: "When I proposed a difference to the standard scenario, you said it would change the answer."
No I did NOT. I said it would change the question. Whether you might get the same answer by different means and different assumptions is irrelevant, and I didn't even address it. Millions of different questions can have the "same" answer, "no" or "yes," for example. So what?
I said that if she was "really" is a gravitational field it would change the circumstances (she would never turnaround and therefore never return to earth, for example).
Let's get this straight, what are your answers to the following questions"
1. Is ANY time dilation, ever, due to relative motion? Yes or no?
2. If yes, is ALL time dilation due to relative motion?
3. If I ask you what the time dilation is due to to motion in case A, are you "answering the question" if you tell me what it would be for time dilation due to gravity in case B?
One Brow said: "Which then begs the question if there is an absolute."
I not sure what you mean about "begs the question" here. East is east, whether is it in on my right, behind me, on my left, or straight ahead of me. You simply can't answer the absolute question with a relatioal (relative answer). If I asked: "how can I tell which way is east," the answer "it will always be to you right" is obviously wrong.
One Brow said: "I agree, but I will go further: you can't claim either clock is objectively correct, period."
Fine, I don't care in the least which defintion of "correct" you choose to take (whether objective or purely relative). I will only ask that you not try to change it later, and shift from a relativistic defintion of "correct" to a absolute one.
One Brow said: "So, neither clock is objectively correct, but they are equally correct."
OK, fine. I will spend a little time here trying to make sure I understand just what you are saying, if you don't mind. Let me ask you:
1. Are they both also "equally incorrect," then?
2. Are they equally "meaningful?"
3. Are they equally "meaningless?"
One Brow said: "The real issue is that there is no absolute answer."
We've been through this several times, but what does this mean?
If I don't know the answer to a question, does that mean there is no answer? If you want to be a strict relativist in the ontological/epistemological realm, I guess you would answer: "Yes" it means there is no answer, because there in no answer "for you." If a baby does not know the answer to the question of 2 + 2 = 4, then that question cannot be answered "by him."
But maybe that's not your position, that's why I'm asking. Would there be a correct answer to the question of 2 + 2 = 4, which was simply correct, independent of how many, or which particular, people knew the answer? Is there any question that has an "objective" answer to it? If so, is that answer correct, even if I don't know it? As I understood you, above, you said there was an objective answer for the question of whether a color is yellow or green (or some other color).
Put another way, if I ask someone who the coach of the Utah Jazz and he says "I don't know," does that mean the Jazz simply have no coach? Suppose you ask me the same question and I say "Jerry Sloan." Is my answer ONLY right "for me," with no objective truth to it?
Suppose someone asks me: "If I'm on main street, which way do I turn to go north>
1. First answer: "If you are going west, then turn right." Is this answer "correct," or only correct "for me," with there being no objective answer?
2. Second answer: "If you are going east, then turn left." Is this answer "correct," or only correct "for me," with there being no objective answer?
3. Third answer: "I can't give you an absolute answer to a question which only asks for a relative answer and gives me insufficient information upon which to determine it." Is this answer "correct," or only correct "for me," with there being no objective criteria to determine if my answer is really correct?
All of the above answer presuppose that Main is istelf an east/west street. Would I change my answers if I was incorrect in that assumption and Main is actually a north/south street.
Yes, I would change 2 of the 3, in the attempt to be helpful. I would not change answer 3. But I would, that aside, I would not say: Do NOT turn left, and do NOT turn right. If you are going south, turn around (180 degrees). If you are going north, don't turn at all.
Would that mean my answers 1 & 2 were "wrong" the first time. Seemingly not...you would still turn left to go north IF you were going east. It's just that, given that Main is itself a north/south street, you can't be going east on it, so it was my assumption that were incorrect, not my answer.
But is there any way to even determine which way Main street is running to begin with, or would that just be observer dependent?
Have you looked at the "specific example" given in the wiki article on the twin paradox? A couple of observations:
1. There is absolutely no hint of a conflict, contradiction and/or paradox in that example. Everybody agrees with everybody in whatever time frame, in advance, that, based on "calculations," the travelling twin will only age 5.14 years in the time the earthlings will age 10.28 years. Why then, does wiki go on to spend a great deal of time showing how to "resolve" a (non-existent) "paradox," using a variety of approach (acceleration, acceleraton plus doppler effects, the gravitational dilation of time based on the equivalence principle, etc.) all with different rationales?
1. All the calculations which combine to achieve their mutual agreement are based upon a variety of assumptions. One (but not the only) thing that in uniformily presupposed by all is that the spaceship will be intrinsically moving away from the earth, and that the earth will NOT moving be intrinsically moving away from the ship (it's motion will only be "apparent," or "relative").
3. From the view of the travellers, the reason that they calculate that they will be "younger" has NOTHING to do with time dilation itself, which seems very curious. It is based strictly on the assumption that the DISTANCE (not time) between them and the star will INSTANTANEOUSLY be cut in half. I say instantantaneosly because wiki explicitly says: "for convenience in this thought experiment the ship is assumed to immediately attain its full speed upon departure." This raises a couple of other questions (and there are many), to wit:
A. How does a change in distance make you age less? Why does distance have to do with time duration? I am older or younger, depending on whether I am 500 or 1000 miles from a fixed point (say Busch Stadium in St. Louis)?
B. Why should I see a star to be, say, 100 trillion miles away, then blink, and suddenly see it to be only 50 trillion miles away? What "causes" this? Is it motion, gravity, or what? It's not time dilation. It will not suddenly take me half the time to get there because time has slowed down, because time has NOT slowed down. It is because the distance has shrunk, not the time.
I asked: "A. How does a change in distance make you age less? Why does distance have to do with time duration? I am older or younger, depending on whether I am 500 or 1000 miles from a fixed point (say Busch Stadium in St. Louis)?"
Please don't respond to this with the obvious "answer." Yes, I fully realize that it will take me 20 hours to get to Busch Stadium at the rate of 100 mph if is 1000 miles away and only 10 hours at the rate of 100 mph if it is only 500 miles away. We all know that, but that aint the question.
Say it's 500 miles. Say I leave at 8:00 A.M at return at 6:00 P.M. to find my ho (who's lazy ass was sleepin when I left) cookin supper. OK....now
Say it's 1000 miles. I leave at the same time, but don't get back until 4:00 A.M. and the lazy-ass ho is "still" sleepin.
Why am now "younger" than her after the first trip? Why would I be even "more younger" in the second case, where St. Louis was 1000 miles away, instead of only 500?
What if I had spent the same time in a my usual way, sittin on my crusty-ass couch drinkin beer? Would I still be younger, if she was busy all day cleanin house and bringin me hundreds of beers? Or would she be younger?
The only possible answer to this (and the other) question(s) seems to be based not on time, and not on distance, but simply on "speed," don't it?
One Brow said: "When I proposed a difference to the standard scenario, you said it would change the answer."
No I did NOT. I said it would change the question.
So, I ask you if the answer would change, you say sure it would, but you really meant it would not? It was a typo?
I said that if she was "really" is a gravitational field it would change the circumstances (she would never turnaround and therefore never return to earth, for example).
So, I ask you if the answer would change, you say sure it would, but you really meant it would not? It was a typo?
Let's get this straight, what are your answers to the following questions"
1. Is ANY time dilation, ever, due to relative motion? Yes or no?
Sure, with the understanding that time dilation is a force-type interpretation.
2. If yes, is ALL time dilation due to relative motion?
No.
3. If I ask you what the time dilation is due to to motion in case A, are you "answering the question" if you tell me what it would be for time dilation due to gravity in case B?
No.
Hey is is my turn?
1. Is time dilation always going to be applied to the person who is "really" moving?
2. Is time dilation always going to be applied based on relativisitic effects?
3. When in identical relativistic conditions, when for external reasons you identify one person as "really" moving in one scenario and a second person as "really" moving in the other scenario, is it the relativistic effects that dominate or the determination of who is "really" moving that controls the direction of the time dilation.
I not sure what you mean about "begs the question" here. East is east, whether is it in on my right, behind me, on my left, or straight ahead of me. You simply can't answer the absolute question with a relatioal (relative answer). If I asked: "how can I tell which way is east," the answer "it will always be to you right" is obviously wrong.
You are relying on an analogy to give a facutal analysis.
OK, fine. I will spend a little time here trying to make sure I understand just what you are saying, if you don't mind. Let me ask you:
1. Are they both also "equally incorrect," then?
2. Are they equally "meaningful?"
3. Are they equally "meaningless?"
Yes to all three. They are equally incorrect for measuring reference frames outside of their own. They are equally meaningful within their individual intertial frameworks, and meaningless as overall measures of the passage of time.
One Brow said: "The real issue is that there is no absolute answer."
We've been through this several times, but what does this mean?
If I don't know the answer to a question, does that mean there is no answer?
This is not what I mean. Is there an absolute best type of music? A best flavor of ice cream? A best genre of movie?
The answers to relativitic questions are observer-dependent, and observers in different environments will get different answers. The answers are objective, but that doesn't make any of these answers absolutely correct. Each objectively correct answer is only correct in a specific reference frame.
Suppose someone asks me: "If I'm on main street, which way do I turn to go north
In this example, north is the same direction for everyone.
But is there any way to even determine which way Main street is running to begin with, or would that just be observer dependent?
The analogous equivalent in relativity is. Everyone can determine objectivelyh which way is North, but they will get different answers in different inertial conditions.
2. All the calculations which combine to achieve their mutual agreement are based upon a variety of assumptions. One (but not the only) thing that in uniformily presupposed by all is that the spaceship will be intrinsically moving away from the earth, and that the earth will NOT moving be intrinsically moving away from the ship (it's motion will only be "apparent," or "relative").
Even more fundamental is that the answer comes from the relative motion of the twins.
3. From the view of the travellers, the reason that they calculate that they will be "younger" has NOTHING to do with time dilation itself, which seems very curious. It is based strictly on the assumption that the DISTANCE (not time) between them and the star will INSTANTANEOUSLY be cut in half. I say instantantaneosly because wiki explicitly says: "for convenience in this thought experiment the ship is assumed to immediately attain its full speed upon departure." This raises a couple of other questions (and there are many), to wit:
I don't see how a near-instantaneous acceleration can be translated into changing the distance.
A. How does a change in distance make you age less? Why does distance have to do with time duration? I am older or younger, depending on whether I am 500 or 1000 miles from a fixed point (say Busch Stadium in St. Louis)?
In the viewpoint where Stella is stationary, or the case where Astro "really" is stationary, the calculations of time dilation (really, contraction) on Terence/Eartha comes from gravitational effects. These effects are directly proportional to the strengh of the gravitational field and their distance from each other (ffrom what I can recall/gather). For ordinary gravitational fields, the strenght of the field is inversely propotional to the square of the distance, so the overall effect around a planet is the the effects weaken the further you are from the planet. In the twin scenario, inverse-square law does not apply, and the compression effects of the gravitational fields are stonger the further away you are.
B. Why should I see a star to be, say, 100 trillion miles away, then blink, and suddenly see it to be only 50 trillion miles away?
Rapid aging and rapid acceleration are not the same as instantaneous travel.
Why am now "younger" than her after the first trip? Why would I be even "more younger" in the second case, where St. Louis was 1000 miles away, instead of only 500?
You are young due to the relativistic effects of the journey, which operated for a longer duration for both of you on the longer trip.
What if I had spent the same time in a my usual way, sittin on my crusty-ass couch drinkin beer? Would I still be younger, if she was busy all day cleanin house and bringin me hundreds of beers? Or would she be younger?
The only possible answer to this (and the other) question(s) seems to be based not on time, and not on distance, but simply on "speed," don't it?
If she is doing the housework at 50 mph, she is engaging in all manner of rapid accelerations. If we take the point of view that your couch is the one doing the moving during the housecleaning, you are being subjected to a continual array of gravitational fields.
Speed is one interpretation, but the interpretations of acceleration and gravity still give the same answers.
One Brow said: "If the earth was moving, the earth twin would be younger even in the GR analysis."
I'm sorry, Eric, but no one can conclude that you have even a rudimentary understanding of SR when, for 400-500 posts now, you have DENIED one of the most elementary and fundamental principles of relativity. Every physicist, from Einstein on, has realized and admitted that, if, in the twin paradox, one reversed the sitation and posited that the rocket ship was at rest while the earth moved away and returned, then the earth twin would be younger.
You have denied this notwithstanding that your position contradicts the implications of your own assertions, notwithstanding I have repeatedly quoted you excerpts from reliable sources that say otherwise, and notwithstanding that it contradicts the fundamental principles of relativity.
Once you got the mistaken notion in your head, you have ignored or misread every single piece of evidence to the contrary. I'm sorry, but you have made yourself look very unreasonable, irrational, and, you might even say "crankish."
You clearly have a mistaken view of the implications of the "GR solution" to the problem and you have apparently put ALL your eggs in that mistaken basket, DESPITE clear warnings that you shouldn't. I have already quoted you phsyicists who say it is NOT a solution to the SR problem, etc., but you ignore these warnings just like all the rest. I can, if you want, show you a few of the reasons why your understanding of the implications of "GR solution" are mistaken, but, then again, I have repeatedly done that already, so what good would it do to repeat it again now?
Maybe you can figure it out for yourself if you carefully read "Einstein's twin paradox solution of 1918," which the wiki article cites and which can be found here: http://en.wikisource.org/wiki/Dialog_about_objections_against_the_theory_of_relativity.
But, let me suggest this: Before you immerse yourself in the ridiculous "GR solution" again, and confuse yourself again, try to clear your head of mistaken notions before entering. First read what Einstien explicitly acknowledges, at that same site, about what SR would say about the twin paradox.
"Critic: The two clocks are initially at rest at point A. They run at the same pace, and let the positions of the hands be the same. We now impart to clock U2 a constant velocity in the positive direction of the x-axis, so that it moves towards B. At B we imagine the velocity reversed, so that clock U2 returns to A. As it arrives at A, the clock is decelerated so that it is once again at rest relative to U1...According to the principle of relativity the whole affair should proceed in the same way if it is represented in a coordinate system K', that is co-moving with clock U2. Then relative to K' it is clock U1 that is moving to and fro, with clock U2 remaining at rest. It then follows that at the end U1 should run behind U2, in contradiction with the above result. Surely even the most devoted followers of the theory will not assert that in the case of two clocks that have been positioned side by side, each one is running behind the other...
Relativist: Your last assertion is of course undisputable."
Einstein goes on the invoke the Langevin "resolution" and say the situations are not equivalent, though, while pointing out that SR does not apply to accelerated motion.
Einstein: "K is such a coordinate system, but not the system K', that is accelerated from time to time. Therefore.. no contradiction can be constructed against the principles of the theory."
In that same "dialog" (remember, Einstein himself is writing all the words attributed to "the critic"), Einstein says:
"Also, let U1 and U2 be two identical clocks that are free from outside influences. These will run at the same pace when they are in close proximity and also at any distance from each other, if they are both at rest relative to K. However, if one of the clocks for example U2, is relative to K in a state of uniform translational motion, then according to the special theory of relativity it should - as perceived from coordinate system K - go at a slower pace than the clock U1 that is at rest relative to K."
This just again states the principle which you have alreadly conceded: "One of the fundamental results of Albert Einstein's special theory of relativity is a phenomenon known as time dilation. Simply put, this result states that time moves more slowly for a moving object than it does for an object at rest."
Once you posit a given point to be "at rest," it is the MOVING clock which will run slower. Whether you can PROVE that the posited point is REALLY at rest is not the question here--you simply treat it as at rest by postulation. If you reverse that assumption (i.e., you posit what was, originally, deemed to be the "moving clock" to be the point which is "at rest") then, once again, it will be the MOVING clock which slows down).
As I understand it, and as appears to be the case from my reading of the "dialogue," Einstein himself conceded the validity of the paradox (i.e., SR really does lead to paradoxical results if the "reality" of acceleraton is not acknowledged).
For this reason, he felt compelled to make acceleration, in the form of "gravity," COMPLETELY responsible for the desired time difference. This task, using GR, required some ridiculous asssumptions about gravitation fields suddenly appeared and disappeared, all while unspecified "external forces" suddenly appeared and disappeared which prevented those very same magically appearing and disappearing gravitional forces from acting upon the "rest" clock.
Even then, all you are left with is this (from the "instantaneous turn-around" explanation previously given: During the Outbound Leg, Terence ages less than two months, according to Stella...During the Inbound Leg, Terence also ages less than two months, according to Stella, by the same computation. The Turnaround Event is instantaneous. Total Terence ageing: less than 4 months, it would seem. Yet Terence is supposed to be over 14 years older when Stella returns! Where did the missing time go?"
How do you turn 4 months into 14 years (as it HAS to be to maintain consistency)? You simply say that you have to instantaneously "add" almost 14 years to the earth clock, all due to the "acceleration" experienced at turn-around. The whole "explanation" is utterly contrived, ridiculous, and unconvincing, I'm afraid.
Note that even in the ridiculous GR solution, the presumed effects of time dilation DUE TO motion do not disappear. They are merely "more than offset" by the much larger, but still separate and distinct, time dilation effects due to gravity.
Wiki itself has an admonition to offer concerning the attempt to apply this "solution" to the SR problem, which, ironically, you yourself have quoted, as I recall, to wit:
"...It should be emphasized that according to Einstein's explanation, this gravitational field is just as "real" as any other field, but in modern interpretation it is only perceptual because it is caused by the traveling twin's acceleration."
In other words, according to the the modern interpretation, the gravitational field is not "real." It is "only perceptual" (an illusion, in other words) because, in reality, it "is caused by the traveling twin's acceleration" (not gravity).
In other words, even if you can create fanciful cases which totally contradict the rather empirically obvious notion that the rocket ship actually accelerates after being loaded up with rocket fuel, etc., and if, after doing so, you can create a lot of fanciful "forces" which simultaneously appear and disappear, and even if you can THEN offer an explanation which (relying on completely different imaginary forces) reach your desired conclusion, the premises of the alternative view are NOT the same. It is therefore not a solution of the "same" problem.
Any attempt to claim that it is indeed the "same solution" to the "same problem" is simply a resort to out and out equivocation.
I said: "As I understand it, and as appears to be the case from my reading of the "dialogue," Einstein himself conceded the validity of the paradox (i.e., SR really does lead to paradoxical results if the "reality" of acceleraton is not acknowledged)."
To understand this, I think it is worth reflecting upon the fact that many physicists at that time thought that, within the confines of SR, the acceleration effects would be such as to completely and exactly offset the motion effects so that, once the travelling clock returned, the two would read the same (rather than give different times). If the clocks read the same, then there would be no difference to account for. Dingle was one of these, and was in full support of SR, until he realized that his original interpretation had been mistaken.
This is also apparent from Einstein's "dialogue" where:
1. The critic asks: "Because the change in the position of the hands of the clock, as judged from K, that might occur during the change of velocity, will not exceed a certain value, and because U2 runs slower than U1 during the motion along the length of A B (as judged from K), clock U2 must, if the length A B is sufficiently long, be running behind U1 - do you agree with that?"
2. And Einstien responds: "Entirely agreed. With regret I have noticed that some authors, who otherwise have a thorough understanding of the theory of relativity, wanted to avoid this inevitable result."
I now restate the comment which immediately followed the excerpt I restated in my last post:
"For this reason, he felt compelled to make acceleration, in the form of "gravity," COMPLETELY responsible for the desired time difference."
Just to clarify "for this reason" is a reference to the otherwise paraxoical results of SR.
To extend my prior analogy about "cause of death," here ya go:
You, as coroner, conclude that the cause of death was a heart attack. I, as the relativist, come in and prove you wrong, as follows:
Sure, it appears that way to you, but here's what "really" happened: One Brow was strangled by Dalmer. He was then dismembered and eaten. Then Dalmer regurgitated all the pieces he had eaten and sewed all the dismembered limbs back on with invisible threads. Then he injected him with a heart-stopping chemical. Viola! The mere "appearance" of a heart attack.
One Brow said: "I don't see how a near-instantaneous acceleration can be translated into changing the distance."
Well, truth be told, I don't either, from any plausible viewpoint, but that's what the "specific example" says happens, ya know?:
"The ship's crew members also calculate the particulars of their trip from their perspective...In their rest frame [my insertion, i.e., once acceleratd] the distance between the Earth and the star system is εd = 0.5d = 2.23 light years (length contraction), for both the outward and return journeys. Each half of the journey takes 2.23 / v = 2.57 years, and the round trip takes 2×2.57 = 5.14 years. Their calculations show that they will arrive home having aged 5.14 years,"
Sorry, but I just now saw you first response (this often happens when I start a post, and then do other things before actually posting it.. I don't see your response when I'm in "post a comment" mode, and as soon as it is posted, the screen changes so that I only see the tail end of my own post.
One Brow asked: Hey is is my turn?
1. Is time dilation always going to be applied to the person who is "really" moving?
Answer: Yes and no: Yes, any time dilation DUE TO MOTION will be attributed to the object that is assumed to be "really" moving. But not ALL dilation effects, if some of those are not imputed to the effects of motion, but rather to gravitational acceleration.
One Brow said: "2. Is time dilation always going to be applied based on relativisitic effects?"
I'm not sure what you're asking, for the same reason that the intended meaning of what you are saying is often unclear, to wit: The reference to "relativistic effects" is very vague and non-specific. Thus, when I try to break speed down to its individual components (time and distance) and try to distinguish each component in terms of it's specific contribution to a given instance of "speed," you just ignore the questions about distinctions and resort to your vague, non-specific reference to "relativistic effects." You just did this above, when you responded to the entire question by saying:
"You are young due to the relativistic effects of the journey, which operated for a longer duration for both of you on the longer trip."
That does not respond to the question, it merely avoids it.
One Brow asked: "3. When in identical relativistic conditions, when for external reasons you identify one person as "really" moving in one scenario and a second person as "really" moving in the other scenario, is it the relativistic effects that dominate or the determination of who is "really" moving that controls the direction of the time dilation."
Once again you resort to the vague phrase "relativistic effects." Ignoring that, see my answer to 1, above. The gravitational contribution to time dilation (to the extent it is involved at all) always overpowers the motion effects in the examples we have considered, such as the GPS system we have discussed. In the wiki "GR solution" the gravitational effect is FOUR TIMES that of each respective leg. In the "intantaneous turn-around" explanation it is about EIGHTY times as much. If you want to "equalize" the two effects (time vs gravitational) then you must make up a scenario where the gravitational effects dominate.
By the way, I think the distinction between time and gravitational effects also accounts for the reason why Van Flandern says the adjusted clock runs fast when on earth. The anticipated time differential due to reduced gravity is contrary to, but much stronger than, the anticipated time differential due to time. Hence, the overall effect is to make the adjusted clock run fast.
This occurred to me some time ago, but I didn't bring it up because I didn't want to complicate an already complicated discussion about other things. But, truth be told, Van Flandern's statement confused me when I was composing my posts on the topic, because I overlooked that he was talking about the combined effect of two distinct phenomenon, whereas I was only trying to discuss one of the two.
For what it's worth, I will throw in this observation:
Whether you account for your ability (mathematically) to always calculate the speed (itself composed on two distinct concepts, time and distance) of light to be the same in terms of distance or time itself strictly depends on your perspective. Let's take an example where a rocket is launched, from earth, "directly at" a distant star.
If the "moving" object is moving away from you in a line (i.e, if you are on earth, in this example), the difference would be accounted for strictly in terms of "foreshortened distance." If you were observing the trip from a a point some distance (say one lightyear) at right angles to the earth, then the difference would be accounted for strictly in terms of "time dilation." For point at some other angle, you would use some combination of length contraction and time dilation to account for it.
That's apparently why they want to call it "spacetime." I suppose you could simply substitute the word "distance" for "space" here and call it "distancetime." You must simply mash the two concepts together in some variation of possible combinations to make the math come out right. Speed is whatever you want it to be, simply according the the way and degree to which you distort newtonian "space" and "time."
If my understanding is correct, then my last post basically summarizes the situation, more or less, even if the precise details may be inaccurate. It is also addressing SR, not GR.
Edit: I often assume that the errors I make will be "obvious," but that is not always true.
Meant to say: "By the way, I think the distinction between time and gravitational effects also accounts for the reason why Van Flandern says the adjusted clock runs fast when on earth. The anticipated time differential due to reduced gravity is contrary to, but much stronger than, the anticipated time differential due to MOTION [not "time"].
I'm sorry, Eric, but no one can conclude that you have even a rudimentary understanding of SR when, for 400-500 posts now, you have DENIED one of the most elementary and fundamental principles of relativity.
I must have done a very poor job of explaining this, or you of understadning me, if you think I have denied anything you put into the first four of those responses to my last comment, with one exception.
... the premises of the alternative view are NOT the same. It is therefore not a solution of the "same" problem.
Of course the conditions of Stella/Terence and Astro/Eartha are not the same, and I never said they were. I only said their relative conditions were the same. Even though the outside influences are different, what Stella experiences is exactly what Astro experiences, and what Terence experiences is exactly what Eartha experiences. This is why their outcomes are the same, despite hugely different intial conditions. No matter how you vary these initial conditions, if the relative motion is the same, so it the outcome. If you don't see that, then you really shouldn't be casting aspersions on my understanding.
One Brow said: "I don't see how a near-instantaneous acceleration can be translated into changing the distance."
Well, truth be told, I don't either, from any plausible viewpoint, but that's what the "specific example" says happens, ya know?
The distance is changed by speed, not acceleration, much less the rapidity of the acceleration.
Answer: Yes and no: Yes, any time dilation DUE TO MOTION will be attributed to the object that is assumed to be "really" moving. But not ALL dilation effects, if some of those are not imputed to the effects of motion, but rather to gravitational acceleration.
Good so far, basically a "no".
One Brow said: "2. Is time dilation always going to be applied based on relativisitic effects?"
I'm not sure what you're asking, for the same reason that the intended meaning of what you are saying is often unclear, to wit: The reference to "relativistic effects" is very vague and non-specific.
I mean, very straightforwardly, how they move relative to their prior movements and each other.
"You are young due to the relativistic effects of the journey, which operated for a longer duration for both of you on the longer trip."
That does not respond to the question, it merely avoids it.
The only possible means to evaluate whether you are younger than the woman in your example is by comparing the spacetime paths you have taken relative to each other.
One Brow asked: "3. When in identical relativistic conditions, when for external reasons you identify one person as "really" moving in one scenario and a second person as "really" moving in the other scenario, is it the relativistic effects that dominate or the determination of who is "really" moving that controls the direction of the time dilation."
Once again you resort to the vague phrase "relativistic effects." Ignoring that, see my answer to 1, above. The gravitational contribution to time dilation (to the extent it is involved at all) always overpowers the motion effects in the examples we have considered, such as the GPS system we have discussed. In the wiki "GR solution" the gravitational effect is FOUR TIMES that of each respective leg. In the "intantaneous turn-around" explanation it is about EIGHTY times as much. If you want to "equalize" the two effects (time vs gravitational) then you must make up a scenario where the gravitational effects dominate.
Sorry, but I don't recall bringing in gravity specifically. It's true that, to adopt many points of view, asserting gravitational forces are needed to explain the motion, but those forces disappear in other frames of reference.
Again, by "relativistic conditions", I mean only how the twins move relative to themselves and each other. Now try to answer 2 and three using that definition.
That's apparently why they want to call it "spacetime." I suppose you could simply substitute the word "distance" for "space" here and call it "distancetime."
Distance refers to an amount of separation. The dimensions are space (3) and time (1), amounts in those dimensions are length (space) and duration (time), and the dot product of those amounts (that is, how far apart things are overall) is a distance.
You must simply mash the two concepts together in some variation of possible combinations to make the math come out right. Speed is whatever you want it to be, simply according the the way and degree to which you distort newtonian "space" and "time."
Or, perhaps the equations show how space mashes itself in in different frameworks.
I said: "Speed is whatever you want it to be, simply according the the way and degree to which you distort newtonian "space" and "time."
What I really meant to say here was "newtonian distance [not space] and time." Note that none of this is dependent upon the actual speed of light. Whatever is it measured to be is irrelevant to the math. It's not what the speed of light "is," that makes the theory work, it is simply what the speed of light is postulated to be.
The "theory" would work just the same if you said the speed of light is ALWAYS 1 billion miles per second instead of 186,000 miles per second. You would change the quantity of the Lorentz-Fitzgerald transformations, sure, but that's it. Then the amount and degree (depending on angle of perception) to which you would distort newtonian distance and time, respectively, would change, but you could still make all the math work out just fine.
For the moment, I will skip over the first part of this post. Believe me, I do intend to return to that part, though.
One Brow said: "The distance is changed by speed, not acceleration, much less the rapidity of the acceleration."
I never said the distance is changed by acceleration. But, that aside, this is a totally confused statement"
"The distance is changed by speed" How does "speed" (of which distance in merely one component) change distance?
If you want to say it is changed by "motion," that too would take a lot of explaning, but that would be different than the absurd claim that "speed" is changed by distance. If anything, changing the distance would simply change the calculated speed (if done in the same amount of time) not vice versa.
One Brow said: "Again, by "relativistic conditions", I mean only how the twins move relative to themselves and each other. Now try to answer 2 and three using that definition."
1. I don't have to "try," I already have answered the question as it specifically relates to motion effects.
2. I am growing quite tired of your interminable attempts to equivocate. If by "relativistic conditions" you simply mean "time dilation due to motion alone," then say that. But more importantly, don't change your defintion from sentence to sentence, paragraph to paragraph, and post to post. Don't use it here to mean ONLY the motion effects and THERE to mean the combined effects of both motion and gravity.
One Brow said: "I must have done a very poor job of explaining this, or you of understadning me"
I have repeatedly asked you this question, but I will ask it one more time:
If, in the "twin paradox" problem, as posed by wiki, you simply reversed the assumption about which object was moving (earth vs spaceship) would the earth twin still be older, or would he be younger?
Edit: meant to say:
"If you want to say it is changed by "motion," that too would take a lot of explaning, but that would be different than the absurd claim that distance is changed by speed."
Distance is what you use (in part) to calculate speed. Distance helps determine speed, speed does not determine it. On the contrary, you cannot calculate speed unless and until you know the pertinent distance.
Math instructor: OK, kids, let me explain speed to you. It's very simple, really. Speed is just a proportion between time and distance, where the distance, when divided by the time elapsed, gives you the speed. Now, based on this, let me ask you a few questions:
1. A car travels 60 miles in one hour. What is it's speed? Class: 60 mph.
2. Very good, class, now, a car travels 120 in two hours. What is it's speed? Class 60 mph.
3. Very good, class, now a car travels 30 miles in 30 minutes. What is it's speed? Class: 60 mph.
Instructor. Very good, you understand the concept of speed perfectly. So, next week, we will do some alegbra problems involving the concept of speed. But, for now, let's just look at one thing:
You notice that your answer was the same to every question, i.e., 60 mph? That wasn't just accident, I set it up that way. Don't start thinking that, no matter what the time or distance, the answer will always be 60 mph.
You will notice that the ratio between minutes passing and miles travelled is always consistent. In fact, is these examples, it is always 1 to 1. 30 miles in 30 minutes; 60 miles in 60 minutes, and 120 miles in 120 minutes. The only reason you get the same answer, 60 mph, to each question is because BOTH the time AND the distance have changed, and they have always done so in such a way that the ratio remains constant. See ya next week....
Next week: I told you we would do some algebra problems this week, using the concept of speed. So, here's the deal: No matter what question I ask you, the answer MUST be "60 mph," got it?
1. A car travels for one minute. How far did it go?
class: One mile.
2. A car travels one mile. How long did it take it? Class: one minute.
3. A car travel an unknown distance for in an unknown amount of time. Answer the question.
Class: We can't answer that question.
Math Instructor: FOOLS! Can't you listen? The answer is 60 mph. I already told you that. You don't have to know a single thing about either the distance or the time to answer the question. I've already given you the answer. You all FLUNK!
Next week: Math Instructor: I've done decided to give y'all a chance to redeem yourselves after your miserable failure last week. Once again, the answer MUST BE "60 mph," got it? First question:
A car goes 360 in one hour. What is it's speed?
Classs: 360 miles an hour.
Instructor: I swear to God, Imma flunk alla yo sorry asses if ya don't wise up. I done tole ya: The answer is 60 mph.
Class: You CAN'T go 360 miles in one hour at the rate of 60 mph. It just won't work.
Instructor. The answer is 60 MPH, get that straight, OK!? Now MAKE it work.
Class: Well, I guess you could say that it really took 6 hours...but that wouldn't answer your question, it would just change it.
Instructor: You're startin to wise up...good to see. The question is irrelevant, see? Only the answer is relevant. Don't worry about what question I asked, just give me the right answer. If you have to change the question, that's fine. Any other answers you can think of?
Class: Well, I guess you could also say that he really did travel for only an hour, but that he only went 60 miles, not 360.
Very good! Any other answers?
Class: Sure, we could sit here all year and come up with a million different ways of getting an answer of 60 mph, so long as the question doesn't even matter. For example, we could say that the time elapsed wasn't really one hour, but two, and that he didn't really travel 360 miles, but only 120. Or we could say...
Instructor: OK, that's enough. You get the idea, no matter what the question, just change either the time elasped and/or the distance travelled to get the answer you want. Now, that's what we call "algebra," see?
This guy also sheds some light on our doppler shift sees/calculates dispute from earlier: "Stella sees (through her telescope) Terence age hardly at all during her Outbound Leg, and nearly the full 14 years during her Inbound Leg. No gap. Of course, she calculates something different, taking into account Doppler shifts and the finite speed of light."
http://math.ucr.edu/home/baez/physics/Relativity/SR/TwinParadox/twin_gap.html
So, she "sees" him age 14 years, eh? Then she gits to "calculatin." Well, aint that special, eh?
The "theory" would work just the same if you said the speed of light is ALWAYS 1 billion miles per second instead of 186,000 miles per second. You would change the quantity of the Lorentz-Fitzgerald transformations, sure, but that's it.
Of course.
One Brow said: "The distance is changed by speed, not acceleration, much less the rapidity of the acceleration."
If you want to say it is changed by "motion," that too would take a lot of explaning, but that would be different than the absurd claim that "speed" is changed by distance. If anything, changing the distance would simply change the calculated speed (if done in the same amount of time) not vice versa.
It's a short-hand, metaphorical way of describing the effects of the Lorentz transformations as seen from different points of view, much like saying clocks slow down/speed up.
One Brow said: "Again, by "relativistic conditions", I mean only how the twins move relative to themselves and each other. Now try to answer 2 and three using that definition."
1. I don't have to "try," I already have answered the question as it specifically relates to motion effects.
What is the final answer for the question?
2. I am growing quite tired of your interminable attempts to equivocate. If by "relativistic conditions" you simply mean "time dilation due to motion alone," then say that.
"Time dilation due to motion alone" is the interpretation from one particular point of view in the twin paradox. We can examine the Eartha/Astro scenario from the point of view that Eartha does not move, and then all time dilation effects are due to "motion alone".
But more importantly, don't change your defintion from sentence to sentence, paragraph to paragraph, and post to post. Don't use it here to mean ONLY the motion effects and THERE to mean the combined effects of both motion and gravity.
The only difference between "ONLY the motion effects" and "the combined effects of both motion and gravity" is the choice of coordinate system, within SR/GR. So any time I use it to mean one, it automatically means the other.
If, in the "twin paradox" problem, as posed by wiki, you simply reversed the assumption about which object was moving (earth vs spaceship) would the earth twin still be older, or would he be younger?
You had a problem with my last answer? Did you miss it, or did you think it was incomplete?
Naturally, if the rocket is attached to the earth, the earth twin will age less.
Distance is what you use (in part) to calculate speed. Distance helps determine speed, speed does not determine it. On the contrary, you cannot calculate speed unless and until you know the pertinent distance.
I'll try to be more careful in the metaphors.
So, she "sees" him age 14 years, eh? Then she gits to "calculatin." Well, aint that special, eh?
Yes, we talked about that a couple of pages ago.
I asked: "If, in the "twin paradox" problem, as posed by wiki, you simply reversed the assumption about which object was moving (earth vs spaceship) would the earth twin still be older, or would he be younger?"
One Brow said: "You had a problem with my last answer? Did you miss it, or did you think it was incomplete?"
You are not answering the question, that I can tell. Can you give me a simple yes or no?
I said: "You are not answering the question, that I can tell. Can you give me a simple yes or no?"
Yes or no, would not apply I guess. Let me re-ask the question:
If, in the twin paradox" problem, as posed by wiki, you simply reversed the assumption about which object was moving (earth vs spaceship) would the earth twin
A. Still be older?
B. Now be younger?
A, or B?
I said: "You are not answering the question, that I can tell."
Hint: As I have told you before, Eric, you have a penchant for answering a question that is not asked. You then pretend to have, and feel smugly confident that you have, "answered the question."
You don't seem to even understand the question. I have already done this for you, in prior posts, but read the question (and the conditions set forth therein) as set forth in wiki BEFORE you try to answer it.
Hint # 2: The various "resolutions" given in wiki are not the "problem." The answer is not the question.
Hint # 3: Pay special attention to this representation made, at the very outset, by wiki: "In physics, the twin paradox is a thought experiment in special relativity..."
Hint # 4: Special relativity is NOT general relativity.
Hint # 5 (which I have already specifically called to your attention):
"But remember, this is not an explanation of the twin paradox."
http://math.ucr.edu/home/baez/physics/Relativity/SR/TwinParadox/twin_gr.html
In context, the second word in that sentence ("this") refers to "the "equivalence principle analysis" as "applied" to the twin paradox."
Hint # 6: Ignore GR for now. Einstein first referred to the clock situation in 1905, long before he came up with GR. Just answer the question asked from the standpoint of SR. A? or B?
Let me qualify on statement that I made before, to wit"
I said: "Every physicist, from Einstein on, has realized and admitted that, if, in the twin paradox, one reversed the sitation and posited that the rocket ship was at rest while the earth moved away and returned, then the earth twin would be younger."
That statement was inaccurate, since many phsyicists have thought that SR must (somehow, if the acceleration effects were quantified) entail that there would be NO age difference whatsoever.
This statement, however, is accurate:
"Every physicist, from Einstein on, has realized and admitted that, if, in the twin paradox, one reversed the sitation and posited that the rocket ship was at rest while the earth moved away and returned, then the earth twin would NOT still be older."
As I have already shown (via quotes) Einstien himself did say that, in those conditions, the earth twin would be younger, however.
Using the standpoint of "just" SR, the only situation in which you can examine the frame where the earth twin is the one moving is the situation where the rocket is attached to the earth instead of to the ship. I have already answered this twice, and will do so again. If the rocket is attached to the planet, of course the planetary twin is the one that ages less.
Now, if you could be clearer about why you think that answer is lacking, that would be helpful. Is there some situation you think is not being discussed?
Edit: Let me clarify that last sentence. To be clear, I should have said:
As I have already shown (via quotes) Einstein himself did say that, in those conditions, the earth twin would be younger, if analyzed in terms of SR, however.
One Brow said: "Using the standpoint of "just" SR, the only situation in which you can examine the frame where the earth twin is the one moving is the situation where the rocket is attached to the earth instead of to the ship."
No, this is wrong. The whole SR problem presupposes that the two are separating from each other, not staying in the same place.
Your "rocket ship must be attached" assertion is totallly contrary to what Einstein himself says about the SR solution.
Here's the "reversed" scenario:
1. A rocket ship, on earth, imparts a force upon the earth which causes it to accelerate away from the ship.
2. The ship remains stationary while the earth accelerates away from it.
3. After some time and distance, the earth uses thrusters to decelerate, turn around, and re-accelerate.
4. After doing so, it returns to earth.
Using SR, which twin, if either, would be younger:
A. The twin who stayed "at home" (the orginal point of departure) in the ship, or
B. The earth twin, who accelerated, moved away "from home" and then returned.
As I have already shown (via quotes) Einstein himself did say that, in those conditions, the earth twin would be younger, if analyzed in terms of SR, however.
In what conditions?
One Brow said: "Using the standpoint of "just" SR, the only situation in which you can examine the frame where the earth twin is the one moving is the situation where the rocket is attached to the earth instead of to the ship."
No, this is wrong.
Really? Please name another possible situation for the planet in an SR framework.
The whole SR problem presupposes that the two are separating from each other, not staying in the same place.
Right, the rocket is on the planet instead of the ship, the rocket moves the planet but not the ship, the planet and the ship separate due to the rocket pushing the planet, etc. Do I need to phrase that for you in any different way?
1. A rocket ship, on earth, imparts a force upon the earth which causes it to accelerate away from the ship.
So, in this scenario, the rocket is not directly attached to the earth, it just pushes it. You think this makes a difference because the rocket attachment is significant?
Using SR, which twin, if either, would be younger:
A. The twin who stayed "at home" (the orginal point of departure) in the ship, or
B. The earth twin, who accelerated, moved away "from home" and then returned.
How many times are you going to ask me to answer the same question? As I have already said, since the earth is being propelled by the rocket (whether directly attached or not), the earth twin is younger.
Edit: Meant to say:
4. After doing so, it returns "home."
Perhaps the word "home" has been confusing you, I don't know. "Home" is not "the earth," in these examples. It is simply the point which remains "at rest" relative to the intrisically moving object.
One Brow said: As I have already said, since the earth is being propelled by the rocket (whether directly attached or not), the earth twin is younger.
Are you sure this is your current answer? It should be, don't get me wrong. But contrary to your "already said" assertion above, it is NOT what you have said before. You have consistently said that, even in the reversed circumstances, the earth twin would be older (not younger, as you say here).
One Brow said: Right, the rocket is on the planet instead of the ship, the rocket moves the planet but not the ship, the planet and the ship separate due to the rocket pushing the planet, etc. Do I need to phrase that for you in any different way?
OK, fine. I misunderstood you to be saying the the ship itself must remain attached to the earth. Rocket or no rocket is irrelevant. Push or no push is irrelevant. The only point is, that, by whatever mechanical means, the ship remains stationary while the earth moves away from it.
Perhaps the word "home" has been confusing you,
No, I understood you to mean the inertial reference frame originally inhabited by the planet and continuously inhabited by the ship in the example.
Are you sure this is your current answer?
It is my current, past, and future answer, and it has not changed since you introduced this scenario. If you have confused with with some other scenario, then the answers may not match, or course.
But contrary to your "already said" assertion above, it is NOT what you have said before.
Then let me apologize for not explaining this to you in a fashion you could understand.
You have consistently said that, even in the reversed circumstances, the earth twin would be older (not younger, as you say here).
No, the earth twin gets older in a couple of scenarios that are *very* different from the one where a rocket is attached to, or pushes, the planet. For example, in the Eartha/Astro scenario. I have been completely consistent on this. If you think you have read a passage that says otherwise, I'll be happy to explain it to you.
OK, I am going to trust that we are on the same page now. Do we agree on this proposition:
Leaving GR out of it, and considering only the premises of SR, the object which is posited to be moving (again, whether we can PROVE it is moving is an entirely separate question), will experience "slower time" than the one that is posited to be "at rest."
At one point (somewhere around post 400) I said: "In other words, as I have said before, it is the attempt to demonstrate than one twin "really" is older and one who "really" is younger, that is misguided and which betrays the very premises it supposedly adopts at the outset."
In response, you said: "In the twin paradox, at the end of the situation both twins are back in the same inertial reference frame and not too distant spatially. This means we can discuss who has experienced a greater passage of time relatively coherently."
====
Shortly thereafter, you quoted me as saying: "In this case it is not "observer-dependent" because there is a "true" answer (and therefore a false, or incorrect, answer) ..."
You then responded with: "In the case of the twin paradox, yes, and both twins arrive at the same answer."
Just so there is no mistake, are you saying that, in the twin paradox, it is possible to know (or at least confidently assert) which of the two twins is really moving?
Leaving GR out of it, and considering only the premises of SR, the object which is posited to be moving (again, whether we can PROVE it is moving is an entirely separate question), will experience "slower time" than the one that is posited to be "at rest."
If we leave GR out of it, the only way something can be moving is through propulsion, and anything not experiencing propulsion will be in an inertial reference frame. The object not in the inertial rest frame will experience less time ("slower time" seems a little vague).
Just so there is no mistake, are you saying that, in the twin paradox, it is possible to know (or at least confidently assert) which of the two twins is really moving?
If you leave aside all considerations of GR, then you have method for constructing a reference frame in which Stella or Astro are stationary. So they must be moving in any reference frame you are allowing yourself to construct. In most reference frames, Terence and Eartha are moving as well.
As usual, "really moving" is basically meaningless until you define what "really not moving" means. Since the defintion you wish to employ requires that one twin is really not moving, and Terence is only choice we are allowing for this role, anything that moves relative to Terence is really moving, by that basically circular definition.
At one point (400-600) you said this: "No, even if you assume Rob is moving and Bob is stationary, the answer is still that Bob will be younger. This comes from a "time slippage" in the not-conserving framework, remember?"
What did you mean?
Given the initial conditions, you can only use the coordinate system where Rob (aka Terence) is moving and Bob (aka Stella) is stationary throughout the while by going outside of SR. If you consider the problem from this viewpoint, Bob/Stella still ages less, even though Rob/Terence is "really" moving in this coordinate system.
We had an ongoing discussion, stretched out over a long series of posts, on the page beginning with post 400, from which I am excerpting below:
I said: Observers, and what they see, has nothing to do with it. They both "see" the other as younger, but one is wrong, and one is right.
You responded: Actually, both are correct.
One Brow said: "The wiki pages do say Rob will be older than Bob, which is also what I have been saying. So, I don't claim the wiki pages have to be wrong, I am afirming they are correct."
I responded: "Then you are affirming that the one who is "really" moving is "really" younger, notwithstanding that each one sees the other as being younger. I.e., one is right, and one is wrong, which is all I said. Your response was that both are correct--not what wiki was sayin."
You said: "The wiki pages do not identify either Bob or Rob as being "correct" or "wrong" at any time. It just describes what they see."
One Brow said: "Are you referring to Pat and Chris (in which case the article says nothing that can even be interpreted that way)..."
I asked: Says nuthin? Really? How ya figure? Because they don't explicitly refer to "Pat" and "Chris," that it?
You said: "Because there are fundamental differences between the Pat/Chris situation and the Bob/Rob situation, and the twin paradox is not remotely applicable to Pat/Chris."
I asked: "Such as? And how do these things change the fundamental underlying principles involved?"
You answered: "Neither Pat nor Chris undergoes acceleration."
I responded: And how would that change the proposition that whoever is "really" going faster is the one who is "really" aging? As you yourself have noted, acceleration is not necessarily important to the wiki answer (depending on whether you want to use a GR or SR answer).
You never directly answered the question, but you said: "It means there can be no single answer to the question without specifying a reference frame first."
===
At the time, I may have dropped it there, but I will pick it up in my next post.
I don't have to know the true facts to know what will be the case IF certain facts are true. For example:
I don't know what time it is, but I do know that if it is now after midnight my life expectancy is short, because my ho swore she would blow me away with the sawed-off if I came in after midnight, and she meant it.
Do you agree (about the first sentence)?
You answered: "Neither Pat nor Chris undergoes acceleration."
What you presumably really mean is that we don't know which one(s) has previously been subjected to accelerating forces. But that does not mean that neither has. In fact, it must be assumed that either one or the other (if not both) has, at some time in the past) been accelerated.
But, ignoring that, what is your response to the question originally asked, to wit:
"And how would that change the proposition that whoever is "really" going faster is the one who is "really" aging? As you yourself have noted, acceleration is not necessarily important to the wiki answer (depending on whether you want to use a GR or SR answer)."
Please don't get semantical on me and you almost invariably try to do. In the question I put "really" in quotes both times. I have told you what I meant by this. You have, as I understand you, already acknowleged that in the twin paradox example (using SR) one twin is "really" younger and is therefore the one who "really" experienced time dilation (in the sense that I am using the term "really").
I said: Observers, and what they see, has nothing to do with it. They both "see" the other as younger, but one is wrong, and one is right.
You responded: Actually, both are correct.
Is this guy wrong, then?
"When our heroes meet again, what do they find? Did time slow down for Stella, making her years younger than her home-bound brother? Or can Stella declare that the Earth did the travelling, so Terence is the younger?
Not to keep anyone in suspense, Special Relativity (SR for short) plumps unequivocally for the first answer: Stella ages less than Terence between the departure and the reunion....We've said why she can't simply adopt Terence's viewpoint...According to Terence, 14 years and a day have elapsed between the Start and Return Events; Stella's clock however reads just a shade over 2 years."
He says it is "unequivocal" that Stella ages less under SR. He doesn't say both are correct (because she can't adopt his viewpoint). He says 14 years have passed, she says two years.
So, then, she "really" did only age 2 years? Why? Because she was the one who was "really" travelling, that's why. Remember, this guy points out that the bogus GR interpretation is just that, bogus, and not a resolution of the twin paradox. An "illusion" of Stella's, if she falls for it.
In particular he says: "Some people claim that the twin paradox can or even must be resolved only by invoking General Relativity (which is built on the Equivalence Principle). This is not true."
With respect to my portion of the question in the foregoing post, i.e, "Observers, and what they see, has nothing to do with it. They both "see" the other as younger, but one is wrong, and one is right," remember that this guy says that Stella "sees" him as aging 14 years. Again, this is strictly in accordance with SR postulates. Each will "see" the other's clock as running slower, remember?
The problem throughout this discussion, Eric, is that you want to continually shift back and forth between to equivocal viewpoints. In paragraph 1, you will say that we can safely assume that one of the two contains instrinic motion with respect to the other, and in paragraph 2 you want to deny that any such thing can be known.
1. Either the earth is moving in orbit around the sun, or it isn't. Ignoring, to repeat, I said IGNORING, gravitational effects, clocks on the sun will run slower than clocks on earth IF that is true.
2. If, in fact, the sun is orbiting the earth, while it remains motionless, then clocks on the sun will run faster than those on the earth.
As Einstien points out, one is perfectly "entitled" under relativity, to assume the earth is motionless. But, of course, no one does. Does the mere, abstract possibility, that the sun "could be" orbiting the earth really mean that "you can't say, and therefore cannot prefer one view over the other?" Does it really mean that the claim that clocks run faster on earth "just as correct" as the opposite claim (that clocks on the sun run faster)?
To say "looking at it this way, then X, while looking at it this way Y" means nothing. If I look at a coin with the heads up, I see heads. If I look at a coin with tails up, I see tails. Does this really mean that the coin I am looking at right now can be either heads or tails up, and that therefore I can't say which?
I said: "1. Either the earth is moving in orbit around the sun, or it isn't."
You want to say: That statement is FALSE, it's both ways, and it's also neither way. It CAN'T be one way or the other, it has to be both, which means it can't be either.
Which means that nothing can be said at all that is meaningful.
I asked: So, then, she "really" did only age 2 years?
Your answer is an unequivocal YES! Whatever your explanation, and however far-fetched and contrived it may be, you still say YES! Why? Because, for whatever reasons, she REALLY did experience more time dilation than her twin. REALLY!
Instead of saying "YES!" why didn't you just say: We don't know; we can't know, we will never know, so there simply is no "yes" or "no" answer to the question.
Why not say that?
I quoted the physicist as saying: ""Some people claim that the twin paradox can or even must be resolved only by invoking General Relativity (which is built on the Equivalence Principle). This is not true."
That is only because Einstein failed to achieve his desired goal with GR, which was to show that all frames of reference are equally reciprocal and symmetrical. In other words, he wanted to formulate a theory which would dictate that the two clocks would agree.
He couldn't achieve that, so he settled for trying to prove that there is no "logical inconsistency" involved. But, by doing so, he undercut his original premise, i.e., that only relative motion can be detected.
If I put one clock on a fast travelling plane, and if it comes back slow, is that not, in itself, a way to detect instrinic, non-relative motion and impute it to the clock on the plane? Sure, some of that difference may be due solely to acceleration, but not ALL of it (as Einstein had hoped to show). For Einstein, it was a given that "acceleration" could be detected, but not motion itself.
In SR, if you assume the ship is moving, then you can assume that time will dilate for it.
If you do assume that, you can use also GR to "assume" that the ship "stayed at rest" (while being subjected to all kinds of magically appearing restraining forces).
OK, fine.
In SR, given the same "apparent" motion between the earth and the ship, if you assume the earth is moving, then you can assume that time will dilate for it.
If you assume that, you can also use GR to "assume" that the earth "stayed at rest" (while being subjected to all kinds of magically appearing restraining forces).
The whole "proof" proves too much. It basically proves that nothing ever moves, not the earth, when it moves, and not the ship when it moves, even though there is relative motion between them.
If nothing ever moves, then time can NEVER slow down for any object due to the effects of motion.
So, bottom line, you can assume that one is at rest, or the that the other is at rest, but you cannot assume BOTH at the same time and therefore assume that there is no "relative" motion between them. So either one OR the other (if not both) is (are) REALLY moving, because the time dilation due to motion is "real," not imaginary.
The fact that two things may be "the same" in one aspect or another does not make them "identical" (i.e, the "same" in each and every conceivable aspect). The logical fallacy of equivocation basically arises when you treat two things as "identical" just because they are the "same" in some aspect.
Unless two things (or situations) are the same exact thing, in the same exact sense, at the same exact time, they are not "identical" even if they are similar in some, or even many, aspect(s).
The thing to remember is that you can treat the earth as moving, or you can treat the ship as moving, but you CANNOT logically treat BOTH as moving and BOTH at rest at the SAME TIME. Take your pick, but don't try to have it BOTH ways, simultaneouly. Einstein, with his GR proof, is basically trying to have it BOTH ways, at the SAME TIME.
In SR, certain assumptions are made, for example, to use Einstein's own words from the SR analysis: "Also, let U1 and U2 be two identical clocks that are free from outside influences."
OK, so no "outside influences," eh? In his GR "solution" he then conjures up all sorts of "outside influences." To begin with, this is simple equivocation. But, furthermore, just as he can conjure up magically appearing forces, I could just as easily conjure up magically appearing forces which totally cancel out his. The result would then be just the same as if there were no "outside influences" whatsover. Who can say that this is not also happening?
He could then conjure up additional forces to offset mine, I could counter with additional forces to offset his additional forces, ad infinitum. There is no end to it, and using this method, you could just as easily conjure up forces in which nothing ever moved (if you don't mind logically contradicting yourself). As long as you are free to change, and even contradict, your own starting assumptions arbitrarily and at any given time, all answers are "equally valid." (See my "math instructor" posts).
I flip a coin and cover it with my hand when it lands, then I say: Heads, or tails, Eric?
You: The coin has two sides, it could be either one.
Me: Naw, it is one or the other, right now, you just don't know which, but let's bet a 12-pack and you go ahead and guess.
You: Ya think I'm sum kinda chump, that it? It could be either one, so that means it can't be either heads or tails. I will lose either way I bet.
One Brow said: "If you consider the problem from this viewpoint, Bob/Stella still ages less, even though Rob/Terence is "really" moving in this coordinate system."
But the aging effects due to motion on Terrence in case two are identical to the aging effects due to motion on Stella in case one. Those don't change. To again quote Einstein: "During the partial processes 2 and 4 the clock U1, going at a velocity v, runs indeed at a slower pace than the resting clock U2."
To deny that the motion effects are identical is simple equivocation. If you just reversed the two in SR, then, in that case also, the motion effects would be identical. It is only the bogus "gravitational" effects which are not equal to case one, because there were NO SUCH FORCES in case one. Einstein: "However, this is more than compensated by a faster pace of U1 during partial process 3 [because] according to the general theory of relativity, a clock will go faster the higher the gravitational potential..."
I have said this all along, but you kept trying to play your equivocation game, while ignoring that point.
Is our friendly physicist right when he makes this claim?: "Terence, on the other hand, does not stay motionless in Stella's frame. The field causes him to accelerate, but he feels nothing new since he's in free fall..."
http://math.ucr.edu/home/baez/physics/Relativity/SR/TwinParadox/twin_gr.html
Can he instantaneously go into "free fall" without "feeling" it?
I said: "As long as you knew which one(s) was (were) "really" moving at what rates of speed, you could say which one was "really younger" even if they had now travelled to a distance of 30 light years apart and NEVER came back together."
You asked: "Really younger from who's point of view?"
From the point of view of the same guy who has a slide rule in hand and who does the "absolutely true and irrefutable" math in this problem, as he does in all the others we have looked at, I guess, eh?
At one point (400-600) you said this: "No, even if you assume Rob is moving and Bob is stationary, the answer is still that Bob will be younger. This comes from a "time slippage" in the not-conserving framework, remember?"
What did you mean?
I was referring to the using the reference frame of the shipboard twin being stationary. The choice of reference frames is arbitrary.
I responded: And how would that change the proposition that whoever is "really" going faster is the one who is "really" aging? As you yourself have noted, acceleration is not necessarily important to the wiki answer (depending on whether you want to use a GR or SR answer).
You never directly answered the question, but you said: "It means there can be no single answer to the question without specifying a reference frame first."
That was as close to a direct answer as I could get. In the Pat/Chris situation, where where neither experiences anything like acceleration or gravity, you can't say who is really younger or really moving without first specifying the reference frame you are using, and the coice of the reference frame is arbitrary.
I don't have to know the true facts to know what will be the case IF certain facts are true. For example:
I don't know what time it is, but I do know that if it is now after midnight my life expectancy is short, because my ho swore she would blow me away with the sawed-off if I came in after midnight, and she meant it.
Do you agree (about the first sentence)?
I beleive you are meaning to say that certain types of facts will be always true or always false regardless of whether you know whether they are true or false, that strips of iron have a certain length even if you have not measured that length, etc. I certainly agree that for various facts, this property (let's call it observer independence) can be true. This does not mean all facts are observer independent.
You answered: "Neither Pat nor Chris undergoes acceleration."
What you presumably really mean is that we don't know which one(s) has previously been subjected to accelerating forces. But that does not mean that neither has. In fact, it must be assumed that either one or the other (if not both) has, at some time in the past) been accelerated.
When you proposed the Pat/Chris scenario, you said they were born in close spatial proximity but very different inertial environments (one moving at .9c compared to the other, IIRC). So, I have been assuming all along that neither Pat nor Chris undergoes acceleration/gravity/change in inertia, and that is one reason why I keep ;ointing out how their scenario is not like the twin paradox.
"And how would that change the proposition that whoever is "really" going faster is the one who is "really" aging? As you yourself have noted, acceleration is not necessarily important to the wiki answer (depending on whether you want to use a GR or SR answer)."
The same relative conditions can be explained, in different coordinate systems, by acceleration, gravity, or some combination of them. Gravity in one coordinate system is acceleration in another.
Please don't get semantical on me and you almost invariably try to do. In the question I put "really" in quotes both times. I have told you what I meant by this.
If all you meant, all along, is that one twin underwent acceleration or a change in inertial frames, I would think you woud have agreed with me when I re-interpreted your use of "really moving" to mean that. So, I don't know what you mean by really moving. The concept of really moving, if it means more than a difference in relative movement, is absent from the wiki page and almost all the other pages we have looked at.
You have, as I understand you, already acknowleged that in the twin paradox example (using SR) one twin is "really" younger and is therefore the one who "really" experienced time dilation (in the sense that I am using the term "really").
One twin is really younger (Stella/Astro). In one reference frame, this is because Stella experiences time dilation. In another reference frame, Eartha experiences time contraction.
I said: Observers, and what they see, has nothing to do with it. They both "see" the other as younger, but one is wrong, and one is right.
You responded: Actually, both are correct.
Is this guy wrong, then?
"When our heroes meet again,
My comment referred to Pat/Chris, not Stella/Terence. Pat/Chris never meet again.
So, then, she "really" did only age 2 years? Why? Because she was the one who was "really" travelling, that's why.
No, its because the relativistic conditions have her in a state where she experiences changes in inertia. Again, since the relativistic conditions are the same, the answer is the same for Stella/Terence and Astro/Eartha, in that Stella and Astro are younger even though we would interpret Stella and Eartha as "really moving" from the viewpoint of conservation of mass-energy (again, assuming that by really moving, you meant something different than just a change in inertial environments).
With respect to my portion of the question in the foregoing post, i.e, "Observers, and what they see, has nothing to do with it. They both "see" the other as younger, but one is wrong, and one is right," remember that this guy says that Stella "sees" him as aging 14 years. Again, this is strictly in accordance with SR postulates. Each will "see" the other's clock as running slower, remember?
On the return journey, Stella will see Astro's clock as running much faster than her own, covering some 13+ years in what she experiences as about 2.5 years.
The problem throughout this discussion, Eric, is that you want to continually shift back and forth between to equivocal viewpoints. In paragraph 1, you will say that we can safely assume that one of the two contains instrinic motion with respect to the other, and in paragraph 2 you want to deny that any such thing can be known.
Let me be clear: any statement of mine you have interpreted to support intrinsic motion/absolute motion/'really moving", which statement does not specifically refer to the conservation of mass-energy, you should think about reinterpreting.
1. Either the earth is moving in orbit around the sun, or it isn't. Ignoring, to repeat, I said IGNORING, gravitational effects, clocks on the sun will run slower than clocks on earth IF that is true.
2. If, in fact, the sun is orbiting the earth, while it remains motionless, then clocks on the sun will run faster than those on the earth.
Since there is no way to test these statements, because gravity *will* be present, I find them to a fun conjecture but not much more. You seem to want to say SR is some separate groupd of effects from GR, but this is not true. GR incorporates and expands SR.
In terms of actual coordinates, from a relativisitic standpoint, the coordinate system where the sun orbits the earth and the one where the earth orbits the sun give the exact same answers in the differences in clock speeds that you will see.
As Einstien points out, one is perfectly "entitled" under relativity, to assume the earth is motionless. But, of course, no one does. Does the mere, abstract possibility, that the sun "could be" orbiting the earth really mean that "you can't say, and therefore cannot prefer one view over the other?" Does it really mean that the claim that clocks run faster on earth "just as correct" as the opposite claim (that clocks on the sun run faster)?
Under relativity, the answers for the two points of view will be the same. The reason to prefer one must come from some principle outside relativity. I'm sure you know by now which one I mean. Three words, one hyphenated, seven syllable.
To say "looking at it this way, then X, while looking at it this way Y" means nothing. If I look at a coin with the heads up, I see heads. If I look at a coin with tails up, I see tails. Does this really mean that the coin I am looking at right now can be either heads or tails up, and that therefore I can't say which?
If the lack of a non-arbitrary way to evaluate Pat/Chris is a problem for you, I don't think i can help you. Reality incorporates paradox. If you want to think deep thoughts, you have to get used to that.
I said: "1. Either the earth is moving in orbit around the sun, or it isn't."
You want to say: That statement is FALSE, it's both ways, and it's also neither way. It CAN'T be one way or the other, it has to be both, which means it can't be either.
Which means that nothing can be said at all that is meaningful.
Actually, I would just say that in relativistic terms, you can describe it either way and everything works out the same. There are other reasons to prefer one framework over the others.
I asked: So, then, she "really" did only age 2 years?
Your answer is an unequivocal YES! Whatever your explanation, and however far-fetched and contrived it may be, you still say YES! Why? Because, for whatever reasons, she REALLY did experience more time dilation than her twin. REALLY!
Instead of saying "YES!" why didn't you just say: We don't know; we can't know, we will never know, so there simply is no "yes" or "no" answer to the question.
Why not say that?
Because that would not be an accurate answer to the question. Having an single answer for Stella/Terence does not guarantee we have one for Pat/Chris.
That is only because Einstein failed to achieve his desired goal with GR, which was to show that all frames of reference are equally reciprocal and symmetrical. In other words, he wanted to formulate a theory which would dictate that the two clocks would agree.
No, no, no. He wanted to, and did, build a theory to show that all frames of reference are equally usuable and will give the same answer to how the clocks will read (in the twin paradox). The same answer regarding the difference, not the same clock readings!
If I put one clock on a fast travelling plane, and if it comes back slow, is that not, in itself, a way to detect instrinic, non-relative motion and impute it to the clock on the plane?
No, it isn't. If you adopt a coordinate system where the plane does not move, you still get the same reult back in terms of hwo the claocks read.
If nothing ever moves, then time can NEVER slow down for any object due to the effects of motion.
You seem to be reading a lot into changes of coordinate systems.
So, bottom line, you can assume that one is at rest, or the that the other is at rest, but you cannot assume BOTH at the same time and therefore assume that there is no "relative" motion between them. So either one OR the other (if not both) is (are) REALLY moving, because the time dilation due to motion is "real," not imaginary.
That, I can agree with. You can't say the ship specifically is "really moving", but you can say there really is motion. Is this what you have meant all along by "really moving"? That, regardles of the coordinate system used, there must be motion somewhere in the system?
The thing to remember is that you can treat the earth as moving, or you can treat the ship as moving, but you CANNOT logically treat BOTH as moving and BOTH at rest at the SAME TIME. Take your pick, but don't try to have it BOTH ways, simultaneouly. Einstein, with his GR proof, is basically trying to have it BOTH ways, at the SAME TIME.
No, Einstein says you have to choose a coordinate system, but that the choice is arbitrary and the answers will come out the same regardless of the choice.
In SR, certain assumptions are made, for example, to use Einstein's own words from the SR analysis: "Also, let U1 and U2 be two identical clocks that are free from outside influences."
OK, so no "outside influences," eh? In his GR "solution" he then conjures up all sorts of "outside influences." To begin with, this is simple equivocation.
By outside influence, Einstein is referring to the clocks being changed or altered by some mechanical process.
But, furthermore, just as he can conjure up magically appearing forces, I could just as easily conjure up magically appearing forces which totally cancel out his. The result would then be just the same as if there were no "outside influences" whatsover. Who can say that this is not also happening?
Since this is a thought experiement, I think Einstein is allowed to choose his own conditions.
Now, in the experiment where we actually sent a clock up in a plane, you can certainly create some interpretation where different forces cacelled each other out.
One Brow said: "If you consider the problem from this viewpoint, Bob/Stella still ages less, even though Rob/Terence is "really" moving in this coordinate system."
But the aging effects due to motion on Terrence in case two are identical to the aging effects due to motion on Stella in case one. Those don't change. To again quote Einstein: "During the partial processes 2 and 4 the clock U1, going at a velocity v, runs indeed at a slower pace than the resting clock U2."
However, the overall aging effects are the same. Why do you feel the need to break off and comparmentalize them?
I have said this all along, but you kept trying to play your equivocation game, while ignoring that point.
It seems to me like saying the Jazz won three quarters in the innesota game last night. They lost the game, talking about the three quarters they won misses the point.
Can he instantaneously go into "free fall" without "feeling" it?
Yes, that's what free fall is. If you jump off a building, you notice the lack of pushing agaisnt gravity because you are used to pushing against gravity (as well as the air rushing by). If you are already in an intertial environment in space, and you come across a gravitational well, you won't notice the difference. Remeber, the instantaneous gravity affects every single object, including every part of his body, in exactly the same way. So, there is nothing for him to notice.
I said: "As long as you knew which one(s) was (were) "really" moving at what rates of speed, you could say which one was "really younger" even if they had now travelled to a distance of 30 light years apart and NEVER came back together."
You asked: "Really younger from who's point of view?"
From the point of view of the same guy who has a slide rule in hand and who does the "absolutely true and irrefutable" math in this problem, as he does in all the others we have looked at, I guess, eh?
Stella/Terence and Astro/Eartha are eventually reunitied in an common inertial environment in close proximity. At that point, they see everything the same way, and we can use their now-shared slide rule to discuss what happened. There is no shared frame of reference avaialble to Pat/Chris.
I asked: "And how would that change the proposition that whoever is "really" going faster is the one who is "really" aging? As you yourself have noted, acceleration is not necessarily important to the wiki answer (depending on whether you want to use a GR or SR answer)."
Your latest response: "The same relative conditions can be explained, in different coordinate systems, by acceleration, gravity, or some combination of them. Gravity in one coordinate system is acceleration in another."
C,mon, Eric. We were only talking about the isolated motion effects. Do I have to spend the rest of life composing a post trying to describe the position of every particle in the universe for you to answer a simple question like this?
One Brow said: "The concept of really moving, if it means more than a difference in relative movement, is absent from the wiki page and almost all the other pages we have looked at."
Suppose there are two objects in space which are separating from each at some speed (whether one inch per year, c, or whatever). Would it be accurate to say that at least one of those two is really moving?
I said: "You have, as I understand you, already acknowleged that in the twin paradox example (using SR) one twin is "really" younger and is therefore the one who "really" experienced time dilation (in the sense that I am using the term "really")."
You said: "One twin is really younger (Stella/Astro). In one reference frame, this is because Stella experiences time dilation. In another reference frame, Eartha experiences time contraction."
Are you talking about the contrast between the GR and SR frames? I specifically said SR, so I wasn't even talking about that. Or do you mean something the frame of some other star?
If the latter, then no question can ever be answered, so let's just quit this whole game now. If you ask me if I am drunk, in my crib, over 30 years old, or any other question you could think of to ask, I simply spam the same "answer," to wit: "There is no answer to that, it all depends on your frame of reference."
I said: "I don't have to know the true facts to know what will be the case IF certain facts are true."
You said: "I beleive you are meaning to say that certain types of facts will be always true or always false regardless of whether you know whether they are true or false."
I agree with that, but that's not what I meant at all. I was simply talking about conditional statements (see the big IF, there?).
I can know that If X, then Y, even if I don't know if X is actually the case.
Me: "You answered: "Neither Pat nor Chris undergoes acceleration."
What you presumably really mean is that we don't know which one(s) has previously been subjected to accelerating forces. But that does not mean that neither has. In fact, it must be assumed that either one or the other (if not both) has, at some time in the past) been accelerated."
When you proposed the Pat/Chris scenario, you said they were born in close spatial proximity but very different inertial environments (one moving at .9c compared to the other, IIRC). So, I have been assuming all along that neither Pat nor Chris undergoes acceleration/gravity/change in inertia, and that is one reason why I keep ;ointing out how their scenario is not like the twin paradox.
Then you miss the point entirely, possibly because the whole original question is out of sight. The whole line of discussion revolved around my statement that IF (see the big IF, there) you knew which one(s) was(were) really moving faster, and by how much, you could tell who was younger (on the basis of the motion effects alone, please don't bring the possibily of gravity along the line as making the question unanswerable--the question presupposes such factors are not in play).
My point is simple:
1. Because they are separting, at least one of the two is really moving, even if the other one is, and always has been, completely stationary.
2. Therefore at least one of them has presumably been accelerated in the past by some means, but that means is totally irrelevant to the question.
3. There is no need whatsoever for either of them to "undergo" acceleration that you personally see in order to answer the question.
4. The fact that the twin paradox did contain known acceleration is irrelevant, it does NOT changing the fundamental principles underlying the twin paradox explanation.
C,mon, Eric. We were only talking about the isolated motion effects. Do I have to spend the rest of life composing a post trying to describe the position of every particle in the universe for you to answer a simple question like this?
If all you are discussing are isolated motion effects, than of course you can't adopt a reference frame with involving other effects. However, this is not a statment that one person is "really" moving, it is a statements that the other person can't be stationary because I refuse to consider that they may be stationary. You have criticized me for my supposed adoption of similarly curcular positions in the past, why do you cling to yours so fiercely?
Suppose there are two objects in space which are separating from each at some speed (whether one inch per year, c, or whatever). Would it be accurate to say that at least one of those two is really moving?
If there would be motion in any avaialble coordinate system, you could say there is really motion. I'm still not sure what "really moving" is supposed to mean. Certainly, you can't identify one or the other as really moving.
You said: "One twin is really younger (Stella/Astro). In one reference frame, this is because Stella experiences time dilation. In another reference frame, Eartha experiences time contraction."
Are you talking about the contrast between the GR and SR frames? I specifically said SR, so I wasn't even talking about that. Or do you mean something the frame of some other star?
Even then, looking only at SR effects, you can come up with reference frames where both twins experience time dilation, but Stella will experience it to a larger degree than Terence, possibly to a much larger degree and for a shorter period of time in that reference frame, while experiencing no time dilation at all in other points of that frame.
If the latter, then no question can ever be answered, so let's just quit this whole game now.
I keep affirming to you that some questions can be definitively answered, so why come back wth this? Think about the the difference between the ones that can be answered (Stella ages less than Terence) and the ones that can't (Pat and Chris), and why they are different. Look up the ladder paradox as well. I think your frustration means your getting close to a breakthrough here.
"There is no answer to that, it all depends on your frame of reference."
Regardless of the frame of reference chosen, Stella ages less than Terence.
I can know that If X, then Y, even if I don't know if X is actually the case.
OK, I agree with that as well.
My point is simple:
1. Because they are separting, at least one of the two is really moving, even if the other one is, and always has been, completely stationary.
You can arbitrarily choose to say Pat is moving. You can arbitrarily choose to say Chris is moving. You can arbitrarily choose to say both are moving (at the same or different rates, arbitrarily, as long as the difference is consistent). You can probably (in GR) invent a truly wacky coordinate system where neither is moving, but that system will be so strange as to be basically unsuable, probably.
2. Therefore at least one of them has presumably been accelerated in the past by some means, but that means is totally irrelevant to the question.
Why, and from what state?
3. There is no need whatsoever for either of them to "undergo" acceleration that you personally see in order to answer the question.
I agree.
4. The fact that the twin paradox did contain known acceleration is irrelevant, it does NOT changing the fundamental principles underlying the twin paradox explanation.
I agree, in the sense that the use of acceleration, per se, is not needed, and you can remove the acceleration component by changing your coordinate system (although you need GR, or at least a couple fo points associated with GR, to analyze the problem from that particular perspective). Regardless of how it is accomplshed, and there are many ways to do so, you do wind up with differences in inertial environments being applied to Stella/Astro.
One Brow said: "No argument there. Do you think the answer would change if, by some miracle, this was not an assumption bt a real state of events?"
Haven't I aready answered this in what I intended to be good faith? And didn't you subquently, by equivocation about the word "answer, by mixing SR premises with (inapplicable and inappropriate) "conclusions," by treating every answer of mine as though it applied to your presumptions, rather than those already established by the author, etc. thereby cause me to waste about 200 posts trying to discuss this with you in good faith by while you clung to your undisclosed assumptions as a means of propetuating confusion so that you could play "clever" word games?
Not again, thanks.
I asked: why don't you just say: "We don't know; we can't know, we will never know, so there simply is no "yes" or "no" answer to the question."
You responded: "Because that would not be an accurate answer to the question. Having an single answer for Stella/Terence does not guarantee we have one for Pat/Chris."
You completely miss the larger point, Eric. You seem to be claiming that there is "a single answer for Stella/Terence," but, by your own recurring statements there can NEVER be a single answer to ANYTHING concerning objects in space.
How can you purport to give ANY meaningful answer, let alone a "single" one? I don't care if you have 35 volumes of relativity theory at your disposal--they are all simply full of "meaningless" statements and erroneous presumpositions. Whatever you claim the "single answer" to be to a given question I can, following Einstien's lead, invent ridiculous assumptions to prove that what you are saying cannot be known. Why bother saying it? How can you ever claim that any answer, however seemingly simple, is knowable or correct?
One Brow said: "No argument there. Do you think the answer would change if, by some miracle, this was not an assumption bt a real state of events?"
Haven't I aready answered this in what I intended to be good faith?
Yes, when I asked it last week on December 10. I'm not sure why you are bring it back into the discussion.
And didn't you subquently, by equivocation about the word "answer, by mixing SR premises with (inapplicable and inappropriate) "conclusions," by treating every answer of mine as though it applied to your presumptions, rather than those already established by the author, etc. thereby cause me to waste about 200 posts trying to discuss this with you in good faith by while you clung to your undisclosed assumptions as a means of propetuating confusion so that you could play "clever" word games?
No, that's certainly not how I interpreted events. I saw the effort as trying to clarify for you that the reason the gravitational forces Stella sees are treated as pseudo-forces has nothing to do with the relativity and everythign to do with conditions outside of what relativity discusses, and as trying to point out that the resolution of the twin paradox does not rest on deciding who is "really moving".
Here it is again, as always: "No, it isn't. If you adopt a coordinate system where the plane does not move, you still get the same reult back in terms of hwo the claocks read."
I have read your claim there several times Eric, but it is utterly meaningless and incomprehensible. I just asked my mongloloid idiot neighbor what it meant, and he read it differntly than I do. It therefore has no meaning and contains no meaningful claims or content.
There, that was easy. Maybe I should responsd to every assertion/claim you make this way, eh!?
To clarify further, it seeed you were seeing the description of the gravitational forces in the Stella-is-stationary interpretation as somehow being relevant to the way relativity appraoches or answers what is happening in the twin paradox. However, this is not true. For the purposes of evaluating what happens within relativitic boundaries, it does not matter in the least whether you have Stella seeing fictitious gravitational influences or Astro seeing real gravitational influences: the answers will always be equal. Astro/Stella will age less than Eartha/Terence by the examct same amount in the exact same manner.
I have read your claim there several times Eric, but it is utterly meaningless and incomprehensible.
Assuming you are serious, what is the difficult part? Tht you can adopt different coordinate systems to describe that same event, that in one such arbitrarily chosen coordinate system the plane and its clock are stationary, or that even after adopting different coordinate systems, the same result pops out?
One Brow said: "No, Einstein says you have to choose a coordinate system, but that the choice is arbitrary and the answers will come out the same regardless of the choice."
This is wrong in at least two respects.
1. The choice is NOT arbitrary in this case. The "choice" he supplies contains two (and only two) viewpoints, one of which is prima facie absurd. There would be good (not arbitrary) reasons to reject it out of hand.
2. The answer will NOT be the same regardless of choice, I could, in theory, pick from thousands of "arbitrary co-ordinate systems," each of which would give a DIFFERENT answer. It would be nearly impossible to get the same answer twice if I just randomly and arbitrarily made up unequal, but opposing, "forces" which magically appear and disappear simultaneously, can't you see that?
In other words, I can always come up with a "Dalhmer et his sorry ass, puked it up, sewed all the pieces back together with invisible magic thread" alternative "explanation" of an apparent heart attack. That kind of absurdity can be "used" against any claim any one ever makes, whatever it's nature.
"You seem to want to say SR is some separate groupd of effects from GR, but this is not true. GR incorporates and expands SR."
Wrong, if you mean the "motion" effects disappear, or are indistinguishable from gravtational effects, in GR. Don't you remember our GPS discussion?
"In terms of actual coordinates, from a relativisitic standpoint, the coordinate system where the sun orbits the earth and the one where the earth orbits the sun give the exact same answers in the differences in clock speeds that you will see."
Yeah, so what? Did I ask anything about whether the "differences" would be the same? Did I even ask anything about what the COMBINED gravitational and time effects would be (I thought I made it CLEAR, VIA REPETITION AND ALL CAPS, that I wasn't talking about that).
The whole "You can't even ask a question about cats because there are also dogs in the world" approach you have to responding to hypothetical questions is, to be blunt, pure bullshit, very annoying, and evasive. I am not gunna continue this discussion if you don't care to do so in good faith.
One Brow said: "By outside influence, Einstein is referring to the clocks being changed or altered by some mechanical process."
He is talking about SR, which consists of frames of references for objects travelling in a straight line at a uniform speed, uninfluenced by gravity, etc. That is what SR is. SR totally ignores gravity, while GR does not. Whether you want to call "gravity" a "mechanical force" or not the whole problem is premised on there being no significant gravitational effects in the problem he is addressing.
Did you think otherwise when you made this statement? If you didn't, what is the signficance of your comment? Why did you make it?
1. ... The "choice" he supplies contains two (and only two) viewpoints, one of which is prima facie absurd.
The EXAMPLE Einstein supplies discusses two choices out of infinitely many, because those are the specific two choices where a) one of the participlants is stationary, and b) people get confused into thinking the results should be symmetrical because of a). Choosing for reasons that have nothing to do with the scenario itself, and everything to do with our ability to use the coordinate systmes involved, is the definition of making an arbitrary choice. Even if you stick to inertial reference frames only, there are an infinite number of such frames where both Stella and Terence are "really" moving, and they all end up with the same ratio of time passing between Terence and Stella. There is no limitation on the number of choices to be had, and the answers are always the same.
2. ... I could, in theory, pick from thousands of "arbitrary co-ordinate systems," each of which would give a DIFFERENT answer.
A different answer in regards to who ages less? No, they don't. Maybe you were thinking about some other question. With regard to who ages less, and in what ratio, every coordinate system gives the exact same answer.
It would be nearly impossible to get the same answer twice if I just randomly and arbitrarily made up unequal, but opposing, "forces" which magically appear and disappear simultaneously, can't you see that?
What does "nearly impossible" mean here? Regardless of the coordinate system chosen, and any force effects that must be present to justify that system, the answers are the same regarding the aging effects. Ask anyone who can do the math.
In other words, I can always come up with a "Dalhmer et his sorry ass, ...
You think a factual difference is the same as a change in coordinate systems?
"You seem to want to say SR is some separate groupd of effects from GR, but this is not true. GR incorporates and expands SR."
Wrong, if you mean the "motion" effects disappear, or are indistinguishable from gravtational effects, in GR.
I don't believe you can reasonbly interpret "incorporate" to mean "cause to vanish" or "make identical to something else".
Did I even ask anything about what the COMBINED gravitational and time effects would be (I thought I made it CLEAR, VIA REPETITION AND ALL CAPS, that I wasn't talking about that).
Why do you care if different components provide different amounts to a sum, when the sum is the same regardless of the coordinate system? This is true even when you change coordinates in Newtonian mechanics.
For example, lets say I shoot a rubber band in a generally NNW direction. I could lay out one set of coordinates where X is inches due east and y is inches due north. I could lay out another where x' is inches due NE and y' is inches due NW. I will get different distances in the x direction than in the x' direction, and different distances in the y direction than in the y' direction. I still get the same distance for how far teh rubber band travled.
Now, when some guy we'll call aintdoingmuch comes along and tells me that my value for x is different from my value for x' because x is a "real" direction and x' is not a "real" direction, and that y adn y' don't matter to teh discussion so we are not supoosed to talking about htme at all, what should I do? Should I engage him in 750+ comments of discussion?
I am not gunna continue this discussion if you don't care to do so in good faith.
Your attampts to say that you only want to discuss one subset of the explanations of an event, and look at any difference that arise in that subset and pretend they are meaningful, when in the whole explanation there is not difference, is the real problem here. It's like were are talking about how to hand a picture on a wall with two nails, and you are saying you don't want to hear about the nail on the right side, just talk about the nail on the left side, and how can the picture hang level with just the left-side nail? Well, that's why they put two nails into the set!
So, clarify specifically want you want to talk about. If you are tryingt o say there is some idea of absolute motion, "really moving" or any other such nonesense being smuggled into SR that goes beyond changing inertial frames, you're just wrong, period. Even if you are not smart enough to understand that your wrong, not perceptive enough to see that you might be wrong, and/or not humble enough to accept you are wrong, you're still wrong. You won't become correct by saying I have to interpret things the way you think they should be interpreted and using circular logic to build your conclusion into your setup.
Whether you want to call "gravity" a "mechanical force" or not the whole problem is premised on there being no significant gravitational effects in the problem he is addressing.
Were you referring to something other than:
http://en.wikisource.org/wiki/Dialog_about_objections_against_the_theory_of_relativity
K' is the reference frame
1. A gravitational field appears, that is directed towards the negative x-axis. Clock U1 is accelerated in free fall, until it has reached velocity v. An external force acts upon clock U2, preventing it from being set in motion by the gravitational field. When the clock U1 has reached velocity v the gravitational field disappears.
One Brow said: "If the lack of a non-arbitrary way to evaluate Pat/Chris is a problem for you, I don't think i can help you."
I don't need help with that, Eric. Nothing I originally said about situation required, or even had ANYTHING to do with, the lack of non-arbirary way to evaluate the problem.
It's true that I wasted many posts RESPONDING to the non sequiturs, contradictions, and equivocations which you brought into that discussion, but that was never my point.
My post did not entail any claim that you could tell who was "really" moving, and that question was, and has at all times since been, irrelevant, notwithstanding your seemingly unique inability to understand a question and/or to discern what is relevant and is not relevant to the issue at hand. It was about the motions effect of SR THEORY (it being taken for granted that SR is itself merely an "arbitrary" way to evaluate the problem--as is GR). The THEORY requires that time dilation effects caused by motion be imputed to the object(s) where are posited to be moving, and this is just as true in your GR (non) solution as it is in SR.
You're the one who seems to need help. You can't seem to understand even the simplest question. You can't seem to refrain from responding with non sequiturs, which you apparently think are clever. You can't seem to separate one distinct thing from another. You can't seem to keep even the most rudimentary points in your head, even after they have been pointed out to, and acknowedged by, you about 15 FUCKING times.
1. A conditional claim DOES NOT require the that the condition has been, or even can be, known. It can be just as valid either way.
2. My daughter can, and does, have a name, whether YOU now, or ever, know it. You're not knowing does NOT mean that she doesn't have a name. Sorry, solipsist.
3. In SR and GR both, the time dilation due to motion is ALWAYS imputed to the object(s) which is deemed to be really moving at the time, never to the things at rest.
4. If, in SR or GR, different objects are deemed to be moving, the "motion" effects imputed to them by SR or GR will still adhere, although perhaps in different amounts.
It won't surprise me if you claim you still don't, and still can't, understand these simple things.
One Brow said: "Were you referring to something other than..."
I was referring to that dialogue, but NOT the part about the GR "solution" which you quoted. The words I quoted were taken directly from the SR discussion contained in that same dialogue.
One Brow said: "However, the overall aging effects are the same. Why do you feel the need to break off and comparmentalize them?"
See my last post. The "need" comes from the to understand them and discuss them intelligently. The better, and more appropriate, question, I think, is this:
Why do you contiously REFUSE to acknowledge the existence of separate and distinct things when they are in fact separate and distinct? Why do you refuse to consider my statements and questions which are for what they are and what they say when they are based on looking at a component of a thing rather than some conglomerate that is irrelevant to the question at hand (such a "speed," when I am talking about distance, or "all time effects," when I am only addressing time effects due to motion)?
It is simply because to prefer sophomoric quibbling, equivocation and word-play to substantive, good faith discussion?
If I make a statement about the behavior of a particular a cat, some or your more likely responses are along the lines of:
1. A cat is a mammal and a dog is a mammal. Neither is more or less a mammal than the other. Therefore they are indistinguishble.
2. Cats and dogs are both mammals, therefore you can't say anything true about cats unless it is equally true of dogs
3. A dog would be behave differently than a cat, so behavior you ascribe to cats cannot be either true or false.
4. Since I could take your statement and insert "dog" in the place where you said "cat," you are wrong.
I could go on, but maybe that's enough for you to get the point. Then again, maybe not, I dunno.
One Brow said: "It seems to me like saying the Jazz won three quarters in the innesota game last night. They lost the game, talking about the three quarters they won misses the point."
I'm sure it does seem that way to you. I might simply see it as a way of saying that the first quarter is not the fourth quarter, but that distinction is probably just due to my stupidity.
Likewise, if I specifically asked you "who was ahead at the end of the first quarter," you would probably deem the only possible, and the only right, answer to be:
"The Jazz lost the game."
You have a tendency to only see your conclusions. All components thereof are therefore irrelevant. You already have your conclusion, all the rest can be deduced, if need be---but there really is no need, so.....
One Brow said: "If you are already in an intertial environment in space, and you come across a gravitational well, you won't notice the difference. Remeber, the instantaneous gravity affects every single object, including every part of his body, in exactly the same way. So, there is nothing for him to notice."
I not convinced this tells the whole story, but assuming it is accurate, how, in the context of the twin paradox, do you account for his explanation in the "earth twin motionless" scenario? He says "Clock U1 is accelerated in free fall, until it has reached velocity"
So that twin (clock) doesn't know he is being accelerated, eh? But that is the very reason most give for being able to "resolve" the paradox in SR. One can't feel the acceleration, and thereby knows he is moving, while the other doesn't.
1. Einstien tries to show how the K' circumstances are "identical to" the K circumstance. But in his K' prime example (part one, just for example) is empirically distinguishable from K. In K' the claim seems to be that NEITHER twin would feel acceleration. The word "feel" here can be interpreted as any empircally detectable change. His claim:
"U1 is accelerated in free fall, until it has reached velocity v. An external force acts upon clock U2, preventing it from being set in motion by the gravitational field."
2. Would it then be then "non-moving" twin who felt forces, since he is getting severe forces imposed on him from both sides (the pulling force of the gravity being offset by the pushing effect of the unspecified "external force")? If everything else in he universe was moving at a rapid speed, and he alone remained "motionless," would the "non-moving" twin not even know it? Would he not even "feel" the powerful "external force" being impressed upon him? Or would all of this be completely oblivious to any empircally perceived alteration by both twins?
3. Whatever the case, it seems that one or both of the twins would be able to empirically distinguish what is happening in K from what happens in K'. Maybe that's why Einstein chose to use non-perceiving "clocks" as his objects, eh?
One Brow said: "Stella/Terence and Astro/Eartha are eventually reunitied in an common inertial environment in close proximity. At that point, they see everything the same way, and we can use their now-shared slide rule to discuss what happened. There is no shared frame of reference avaialble to Pat/Chris."
And the relevance of your last sentence is what, exactly?
One Brow said: "However, this is not a statment that one person is "really" moving, it is a statements that the other person can't be stationary because I refuse to consider that they may be stationary."
The "statement" in question was this:
I asked: "And how would that change the proposition that whoever is "really" going faster is the one who is "really" aging?
The statement is strictly conditional and it is NOT what you say it is by any stretch of the imagination. It says nothing about "who" is moving or who is "stationary" whatsoever let alone that one or the other "can't be stationary."
My post did not entail any claim that you could tell who was "really" moving,
Then I'll drop that.
It was about the motions effect of SR THEORY (it being taken for granted that SR is itself merely an "arbitrary" way to evaluate the problem--as is GR). The THEORY requires that time dilation effects caused by motion be imputed to the object(s) where are posited to be moving, and this is just as true in your GR (non) solution as it is in SR.
Again, if "posited to be moving" means "in an inertial frame that changes", that's exactly what I said a few hundred posts ago. If it means more than a changing inertial frame, and you don't mean absolute motion or really moving or anything like that, then what else do you mean?
Now, I can accept that what you meant by the phrase has changed over the last few hyundred posts; that's been my goal after all. but if it hasn't changed, you still have not explained how it is different from simply being the inertial frame that changes, and your attempts so far have involved concepts you have since disavowed.
You're the one who seems to need help. You can't seem to understand even the simplest question.
If you ask a simple question with a faulty premise, the answer may not be simple. The classic example would be "Have you stppped beating your wife?" Answering that either yes or no would be a lie if you have never beaten your wife (except in a strictly formal sense).
You can't seem to refrain from responding with non sequiturs, which you apparently think are clever.
My apparent non-sequitus are attempts to steer the question into a framework that is accurate.
1. A conditional claim DOES NOT require the that the condition has been, or even can be, known. It can be just as valid either way.
Of course.
2. My daughter can, and does, have a name, whether YOU now, or ever, know it. You're not knowing does NOT mean that she doesn't have a name. Sorry, solipsist.
Of course. However, your daughter will have the same last name to every person who does know it.
3. In SR and GR both, the time dilation due to motion is ALWAYS imputed to the object(s) which is deemed to be really moving at the time, never to the things at rest.
'My post did not entail any claim that you could tell who was "really" moving, '
'the time dilation due to motion is ALWAYS imputed to the object(s) which is deemed to be really moving at the time'
Putting those together, you are claiming that time dilation can never be decisively imputed? That's not the case.
Also, you still haven't given a definition for really moving that is something other than a change in inertial rest frames or the experience of acceleration.
4. If, in SR or GR, different objects are deemed to be moving, the "motion" effects imputed to them by SR or GR will still adhere, although perhaps in different amounts.
Of course.
One Brow said: "Even then, looking only at SR effects, you can come up with reference frames where both twins experience time dilation, but Stella will experience it to a larger degree than Terence, possibly to a much larger degree and for a shorter period of time in that reference frame, while experiencing no time dilation at all in other points of that frame."
So, I take it then, that you now want to retract everything you said about the resolutions in the wiki article being in any sense "correct," eh? Assuming you could "come up with" what you say you can, then just apply those scenarios to wiki and you will realize that every word written there was utterly incomplete and inaccurate, if not downright meaningless.
One Brow said: "I keep affirming to you that some questions can be definitively answered..."
1. But you do so very selectively, and your selection is NOT based upon any uniform standard.
2. Until you realize that your claims that all answers are correct and/or that no answers are correct because they can always be looked at from a different perspective can be applied to your own claims just as easily as you apply them to the claims of all others, I don't think you're anywhere near a breakthrough. Whatever assumptions I posit (and I do mean posit---simply knowingly assert, without purporting to know or prove) are countered by you with "that can be seen another way." Same for your assumptions, I'm afraid.
If I try to make a point by analogy, or by reference to a hypothetical situation, such as "if the earth were perfectly spherical," it wouldn't matter to you what I said thereafter. You would simply condescending wise me up by saying "The earth isn't perfectly spherical," and move on.
I was referring to that dialogue, but NOT the part about the GR "solution" which you quoted. The words I quoted were taken directly from the SR discussion contained in that same dialogue.
You said there was a presumption that there were no gravitational effects. This is true in the coordinate system K in the reference, but not in K'. In other words, Einstein is saying that there are no gravitational forces from one point of view, but there are gavitational forces from a different point of view.
Why do you contiously REFUSE to acknowledge the existence of separate and distinct things when they are in fact separate and distinct?
Because they are not "in fact speparate and distinct". The time dilation/contraction effects of SR and GR are the same thing considered from different points of view. This is one of the false premises your questions have been using that make my answers seem like non sequiturs to you.
Why do you refuse to consider my statements and questions which are for what they are and what they say when they are based on looking at a component of a thing rather than some conglomerate that is irrelevant to the question at hand (such a "speed," when I am talking about distance, or "all time effects," when I am only addressing time effects due to motion)?
Because many of the distinctions you are trying to create exist only as points of view, not as different phenomena, and I am trying to help you see that.
Likewise, if I specifically asked you "who was ahead at the end of the first quarter," you would probably deem the only possible, and the only right, answer to be:
"The Jazz lost the game."
No, that happens to have an objective answer.
So that twin (clock) doesn't know he is being accelerated, eh? But that is the very reason most give for being able to "resolve" the paradox in SR. One can't feel the acceleration, and thereby knows he is moving, while the other doesn't.
However, in coordinate system K', it is still the shipboard clock that feels the effects of gravity/acceleration, even though it does not move, while earth-bound clock moves, but does not feel the effects of acceleration/gravity.
1. Einstien tries to show how the K' circumstances are "identical to" the K circumstance. But in his K' prime example (part one, just for example) is empirically distinguishable from K. In K' the claim seems to be that NEITHER twin would feel acceleration. The word "feel" here can be interpreted as any empircally detectable change. His claim:
"U1 is accelerated in free fall, until it has reached velocity v. An external force acts upon clock U2, preventing it from being set in motion by the gravitational field."
U2 is not set in motion. It *does* feel the effects of gravity. In that regard, K' is not empircally distinguishabvle from K.
2. Would it then be then "non-moving" twin who felt forces, since he is getting severe forces imposed on him from both sides (the pulling force of the gravity being offset by the pushing effect of the unspecified "external force")?
Yes! ( I think were getting close here).
If everything else in he universe was moving at a rapid speed, and he alone remained "motionless," would the "non-moving" twin not even know it?
No! It would look to him exactly like he was moving and nothing else was. Neither twin can distinguish K from K'.
Would he not even "feel" the powerful "external force" being impressed upon him?
The shipboard twin does feel the gravitational effects in K'.
3. Whatever the case, it seems that one or both of the twins would be able to empirically distinguish what is happening in K from what happens in K'. Maybe that's why Einstein chose to use non-perceiving "clocks" as his objects, eh?
Actually, the point of the Equivalencxe Principle is that they have no empirical way to distinguish K from K'.
"There is no shared frame of reference avaialble to Pat/Chris."
And the relevance of your last sentence is what, exactly?
This is why there can never be an answer to whether Pat or Chris is younger without first specifying a reference frame,. and since all reference frames are arbitrary choices, there can never be a definitive answer to which is younger.
One Brow said: "However, this is not a statment that one person is "really" moving, it is a statements that the other person can't be stationary because I refuse to consider that they may be stationary."
The "statement" in question was this:
I asked: "And how would that change the proposition that whoever is "really" going faster is the one who is "really" aging?
The statement is strictly conditional and it is NOT what you say it is by any stretch of the imagination. It says nothing about "who" is moving or who is "stationary" whatsoever let alone that one or the other "can't be stationary."
From what I can tell, I was responging to:
"We were only talking about the isolated motion effects." in regards to the twin paradox.
There is no such thing as the "isolated motion effects", as least not in a way that can describe the paradox in total, unless you restrict yourself to the type of coordinate system that does not allow the shipboard twin to be considered stationary. What you are doing is saying, "I am ruling out any coordinate system where Stella can be considered not to be moving,'", and then following that with "in SR, Stella experiences time dilation because Stella is the one that is moving". Do you see the circularity?
Really, Eric, you seem to have taken on the persona of a high school sophomore who, having concluded that nothing can be proven with absolute certainty, thereafter responds to every statement he hears with the "response" that:
"You can't know that for certain. You can't know anything for certain. You know absolutely NOTHING."
By that one simple rhetorical tactic, he can thereby feel at least equal to, if not downright superior to, everyone he meets. Better yet, he doesn't even have to think about, or understand, a single word they say in order for him to say it.
So, I take it then, that you now want to retract everything you said about the resolutions in the wiki article being in any sense "correct," eh?
The wiki article addresses two reference frames, the one where Terence is stationary, and the one where Stella is stationary. Within these reference freams, it is correct. Of course, since reference frames are arbitrary, you can make the numbers involved arbitrarily small in different reference frames.
Assuming you could "come up with" what you say you can, then just apply those scenarios to wiki and you will realize that every word written there was utterly incomplete and inaccurate, if not downright meaningless.
Any statement of duration or length is only meaningful in some agreed-to reference frame. None are universal.
One Brow said: "I keep affirming to you that some questions can be definitively answered..."
1. But you do so very selectively, and your selection is NOT based upon any uniform standard.
I hoping that, by the time this discussion is over, you will see that it is in fact a uniform standard.
2. Until you realize that your claims that all answers are correct and/or that no answers are correct because they can always be looked at from a different perspective can be applied to your own claims just as easily as you apply them to the claims of all others, I don't think you're anywhere near a breakthrough.
With regard to relativistic phenomena, I am already aware of this.
Whatever assumptions I posit (and I do mean posit---simply knowingly assert, without purporting to know or prove) are countered by you with "that can be seen another way." Same for your assumptions, I'm afraid.
Of course.
If I try to make a point by analogy, or by reference to a hypothetical situation, such as "if the earth were perfectly spherical," it wouldn't matter to you what I said thereafter. You would simply condescending wise me up by saying "The earth isn't perfectly spherical," and move on.
I can see where you would find that frustrating, but that is not what I am trying to do.
"You can't know that for certain. You can't know anything for certain. You know absolutely NOTHING."
Except I'm not saying that's true about everything, or even random things, but about very specific types of phenomena where it does seem to be true, and even then, it's "you can't know it for certain until you choose how you are going to look at it first, and there is no one correct way to look at it".
One Brow said: "Regardless of the frame of reference chosen, Stella ages less than Terence."
WHAT!? I could no doubt dream up an scenario, a la Einstien, where Terence ages less than Stella? Suddenly there are now only "two" possible perspectives?
That surprise aside, so what? What is your point, if you have one?
You also seem to ignore the statements of the physicists that the one perspective is NOT a solution to the twin paradox, the admonitions of wiki indicating that one of those perspectives is considered to be completely illusory, etc. None of that seems to matter in the least to you. You keep bringin up this worn-out claim post after post after post after post after post....
I said: "2. Therefore at least one of them has presumably been accelerated in the past by some means, but that means is totally irrelevant to the question."
You asked: Why, and from what state?
It's irrelevant to the question, but, if you really want answers, how's this:
1. From what state? Originally, from an "at rest" state before the big bang, as far as material component of the object is concerned
2. Why? Good question. Because, cause a body in motion will stay in motion until acted upon by an outside force, maybe? Is that an answer? That was Newton's answer. Einstein took on Newton's inertia principle, whole cloth. It is NOT an answer for the "relationalists" like Mach, Liebniz, back in Newton's time, and many others. How's this: The lack of explanation for the origin of inertia is considered by most to be a major empirical weakness of relativity. If them guys can't figure it out, I sho nuff can't, so ask someone else "why?"
One Brow said: "Regardless of the frame of reference chosen, Stella ages less than Terence."
WHAT!? I could no doubt dream up an scenario, a la Einstien, where Terence ages less than Stella? Suddenly there are now only "two" possible perspectives?
There are infinitely many perspective. However, a different perspecitve is not a different scenario.
That surprise aside, so what? What is your point, if you have one?
My point of view on what? What are discussing where my point of view changes things?
You also seem to ignore the statements of the physicists that the one perspective is NOT a solution to the twin paradox, the admonitions of wiki indicating that one of those perspectives is considered to be completely illusory, etc. None of that seems to matter in the least to you. You keep bringin up this worn-out claim post after post after post after post after post....
When they say it is "not a solution", what does that mean to you?
It's irrelevant to the question, but, if you really want answers,
So, you are saying the matter that bacame Pat and Chris had been accelerated? OK, I'm good with that.
I said: "4. The fact that the twin paradox did contain known acceleration is irrelevant, it does NOT changing the fundamental principles underlying the twin paradox explanation."
You said: "I agree, in the sense that the use of acceleration, per se, is not needed"
Well, that's not the revelant sense for this problem. The "fundamental" principle in question, which I have been stating all along is simply that, according to both SR and GR (both of which could be utterly wrong, for all I know), *some* time dilation is imputed to moving objects, due to motion alone. No such time dilation is imputed to motionless objects. If one object is moving faster than another from any perspective you choose, then the one moving faster will experince greater time dilation.
Take any problem you might want so solve with GR. Make it a complicated on. Let's have dozens of highly-paid theorists working on it 24/7 for months with a high-speed super-computer which takes up a whole building. To get *any* answer at all, they have to choose one (or more) "frames of reference."
No matter their precious solution is when it comes out, I can simply say: "But that answer would be different if you had chosen a different frame of reference."
That is understood. That is ALWAYS true. If that is your objection to every GR calculation, then just give up on the whole theory. It can never give one answer which is "true" or "accurate" from ALL possible perspectives.
One Brow said: "trying to point out that the resolution of the twin paradox does not rest on deciding who is "really moving".
Number one: The GR crap is not a "resolution" to the SR problem, and it does not "solve" the SR question even if you can get the same answer. Take the case where, in SR, the earth is "really" moving. In that case, the earth twin will be younger. Now use GR to reverse the presumptions, and keep the earth twin stationary. Now, once again, the earth twin is "really" younger. The paradox comes right back. By mismatching SR and GR, but reversing assumptions, in one set of cases it is the "earthtwin" who is "really younger," while in the other it is the ship twin. Each in "younger than the other," depending on how you do it. It is not a solution to the paradox. Furthermore, the GR (non) solutiom does NOT change the basic assumption of SR concerning time dilation due to motion.
But none of the above need even be said, so far as the wiki problem goes. In wiki, the issue of who's really moving is NOT even an issue, and it is not ambiguous or subject to dispute. In the wiki set-up for the twin paradox problem, the question of who is "really" moving is posited in the very first sentence. There is no call or reason to argue about what it is, because it is clearly set forth at the very outset. I repeatedly urged you to pay attention to this. Changing the assumptions, and thereby the question, is not a way to "answer the question," even if you get the same answer (again, see my "math instructor" posts).
From there, all the "resolutions" in wiki presuppose that the stated twin is moving while the earth twin "stays home." As I have repeatedly pointed out to you, that set of presumptions INCLUDES the GR solution in wiki. The "GR" resolution, as presented, does NOT take the perspective that the "earthtwin" is stationary. It continues, without qualification, to present the different perspectives of the "stay at home" twin versus the "travelling twin." Their reference to Einstein notwithstanding, they are not taking the same perspective as he took in his paper. They are taking a case where the earthtwin turns out to be "really older," that's all (remember, under GR, you can make the earth twin really older, or really younger, depending on which SR answer you want to make it equal).
You refused to consider or acknowledge any of these points. You just tried to use the (conflated) "answer" given by Einstein to imply false claims about the effect of time dilation motion imposes, which is a fundamental assumption of both GR and SR.
In addition to everything already said, the SR problem requires an SR solution (if there is one, and, as I have said, wiki never even gives one). "The standard textbook approach" as given by wiki, does indeed require acceleration, but not to solve the problem. It uses it for two purposes:
1. To show that one is "really moving" (changed inertial frames) so that it is "really" the ship twin who is younger, because it was that twin that moved, and
2. To totally remove the apparent paradox from the realm of SR, since SR does even not address accelerated motion
One Brow said: "Stella seeing fictitious gravitational influences or Astro seeing real gravitational influences: the answers will always be equal. Astro/Stella will age less than Eartha/Terence by the examct same amount in the exact same manner."
This "always be equal" stuff is just plain false, for many reasons which I have already stated. I will repeat two of them here:
1. For any answer you can create an "equal" result, I can create virtually an infinite amount of made-up circumstances which will give an unequal result where Stella does not age less by the exact same amount.
2. As said above, if, in SR, the earth is treated moving, the earthtwin will be younger, not older. You can then use a GR analysis to get an "equal" answer i.e., that Terrence is younger. That is the complete opposite of your claim that "Astro/Stella will age less than Eartha/Terence by the examct same amount in the exact same manner." In my counter-scenario, Stella does NOT age less, she ages more.
One Brow said; "Stella seeing fictitious gravitational influences or Astro seeing real gravitational influences: the answers will always be equal."
1. If they are all fictional, then you are simply dealing with an unadorned, uncomplicated SR problem where GR has absolutely nothing to say or contribute.
2. If one of the forces "is" real, but one of the new imaginary forces (Einstien's "external force") isn't, then, as I said initally, you get wildly different results which are certainly not "equal to" the SR results.
3. The new forces must not only both be present,but they must also magically appear and disappear simultaneously. So, given the problem's set-up, if Stella doesn't "turn on her thrusters" because she has no plans to turn around at that time, but rather in another 5 minutes, the magically appearing gravitational force will pull her backwards. If she tries to overcome this sudden change of direction by using her thrusters, that might work until they run out of fuel, in which case she's gone for good and will never return to earth.
All kinds of special assumptions are built into your "will always give equal answers" approach. You say "always" because you just assume your chosen assumptions have to "always" be true. This simply shows how selectively you apply your "that will not always be the case in every frame of reference" brand of "refutation." You never seem to apply that logic to your own assumptions, just those of your "opponent."
"To clarify further, it seeed you were seeing the description of the gravitational forces in the Stella-is-stationary interpretation as somehow being relevant to the way relativity appraoches or answers what is happening in the twin paradox. However, this is not true."
Yes, indeed I was seeing "gravitional forces" as being relevant to the SR problem--they aint there. Once again, you simply conflate two distinct concepts (SR & GR) into "one" and call it all "relativity." For our purposes that distinction was crucial, as was the distinct between gravitational contraction and "speed" dilation.
That was why I kept trying to keep you from treating them as the "same" thing. And you still can't fathom why they should ever be treated as distinct, I guess, given your "Jazz lose" post. Your conclusions are fine, but meaning of, and rationale for, reaching them is more what I'm interested in. I wish you were as interested in mine, as I am in yours. I'm interested in an analytical discussion, not evasive "verbal combat."
One Brow said: "The wiki article addresses two reference frames, the one where Terence is stationary, and the one where Stella is stationary."
See my prior post on this. Can you point out even one place where wiki says, or even remotely indicates, that "in this solution, we are addressing the solution where Stella is stationary?" It says no such thing, that I've seen (for the reasons stated above). I think you are just reading something into it that you got from another author, based on different assumptions. The whole context of the specific statements made by wiki indicate the exact opposite, to me, as I have repeatedly point out to you (and which you have repeatedly just totally ignored).
I have read your claim there several times Eric, but it is utterly meaningless and incomprehensible.
Assuming you are serious, what is the difficult part?
I'm not serious, and you probably realize if you read what I said about a mongoloid idiot. You can write a sentence (and I make give it, or take from it, a particular meaning). I ask a mongoloid idiot what he thinks it means, and he gives a "completely different" answer. Now what?
Well, since he can give it a different meaning that I do, it obviously has no "real" or "true" meaning. It is meaningless, given the rationale used here.
You quoted me saying: "1. ... The "choice" he supplies contains two (and only two) viewpoints, one of which is prima facie absurd."
You responded: "There is no limitation on the number of choices to be had, and the answers are always the same."
See, Eric, this is just another example of a case where you fail to make relevant distinctions, and call different things "the same" without reflection.
Before proceeding, I want to distinguish between 3 different things:
1. The GR solution to any given problem involving motion and/or gravitation,
2. Einstein's attempt to resolve the SR paradox,
3. The suggestion, to the extent it actually appears (or even appears to appear), by one or more authors we have read, that GR gives the "same answer" as SR to the same question.
Three different situations, OK?
Let me address #1 first. I will grant you that GR always agrees WITH ITSELF! But that is quite different than saying it always agrees with SR, as you have suggested.
Let me now address #2 briefly. #2 is NOT #1. If GR wanted to "answer questions" about a spaceship's contemplated travel to a distant star and back, it would not, repeat NOT, throw in simultaneously appearing and disappearing opposing but "forces" to answer that question. Einstein is not even attempting to answer the simple question of how GR would calculate the time distortion results of a trip to a distant star and then back in his "dialogue" discussion.
He IS trying to pretend that he is answering a paradox that appears is SR. This fact is made even more clear by his immediately preceding discussion of the problem in SR and his ultimate claim to have "solved the paradox." So the two situations (discussed here under 2) do not involve EITHER the same question OR the same answer.
3. Wiki seems to kinda (but not really) suggest that GR gives the same answer as SR. The other author also tries to suggest that if SR says one will age 5.14 years and the other 10.28, GR CAN BE MADE to give that same answer IF all kinds of dubious forces are brought in to make that happen. 2 & 3 are similar, but at least one of these guys in 3 finally expressly admits that: "The Equivalence Principle analysis of the twin paradox does not use any real gravity, and so does not use any General Relativity. (General Relativity is the study of real gravitational fields, not pseudo ones, so it has nothing to say about the twin paradox.)" So it does not really purport to be using GR."
Continued next post....
Now, you have been claiming that GR gives the same solution as SR. Let's assume that's actually true.
If, in SR, you assumed the ship twin was the one moving, then SR would say the ship twin was 5.14 years younger, and, if you are right, then GR would agree! But, alas...
If, in SR, you assumed the earth twin was the one moving, then SR would say the earth twin was 5.14 years younger, and, if you are right, then GR would agree!
GR does not solve the paradox. Nor does it give the "same" answer as SR, because, as all authors say, SR does not give ANY answer. It does, however, tell you that one twin will be half (or whatever the beginning assumptions dictate) the age of the other, as it stands. Straightforward GR cannot possibly give these same quantative answers (5.14 vs 10.28 years, for example), because straighforward GR does not bring in magically appearing forces willy-nilly to make those numbers somehow match.
So, two final distinctions to make (or reinforce, as the case may be):
1. GR "solutions" are not the same (in number of years aging, etc.) as SR solutions to a given problem, in any event.
2. Trying to match SR calculations with GR calculations by, as Einstien did, by inventing totally bogus "forces" is NOT giving the "same" answer to the "same" problem. All the assumptions have changed from SR, so it cannot be the SAME problem, even if you can rig it to reach the so-called "same" answer.
3. The fact that GR agrees with itself does prove not mean it agrees with something different. Yet the fact that GR agrees with GR seems to somehow have given you a false impression in that sense.
One final observation about the (GR) "equivalence principle analysis" of the (SR) "twin paradox problem." All GR ends up giving you is a huge "time gap." The amount of that "gap" is...what? It is the gap between the age the earth twin is "supposed to be" by the (SR) calculations (14 years), and the minimal amount of time deemed to have elapsed (less than 4 months) calculated (by Stella, using SR assumptions). Well, basically by saying Stella had to "turn-around," I guess. Not particularly persuasive, doppler effect re-calculation, or not.
Edit: last paragraph, last post, should have said:
How is this gap "explained?" By calling it an "accounting error." Which means what? Caused by what? Well, basically caused by the fact that Stella had to "turn-around," I guess. Not particularly persuasive, doppler effect re-calculation, or not. In short, the GR solution is not "the same" as the SR solution...a huge gap is still left to "account" for.
One Brow said: "This is why there can never be an answer to whether Pat or Chris is younger without first specifying a reference frame,. and since all reference frames are arbitrary choices, there can never be a definitive answer to which is younger."
Then you still don't understand the simple points that I have already pointed out at least, now, 16 FUCKING times. Either that, or else you don't even understand the issue in question, as your next comment suggests:
One Brow said: "There is no such thing as the "isolated motion effects", as least not in a way that can describe the paradox in total, unless you restrict yourself to the type of coordinate system that does not allow the shipboard twin to be considered stationary. What you are doing is saying, "I am ruling out any coordinate system where Stella can be considered not to be moving,'", and then following that with "in SR, Stella experiences time dilation because Stella is the one that is moving". Do you see the circularity?"
I haven't even tried to figure out what you mean by this. The whole situation relates to Pat and Chris, not Stella, so I won't bother.
I've already made a lot of (presumably unread) posts on this whole topic. If after reading them (and I hope at least trying to understand them) this is still an issue for you, let me know.
I will throw out this challenge though, since you are a mathematician and claim to have studied the mathematics of GR. Break out your old textbooks and your calculator, then do this:
To begin with, first assume that two twins are next to each other, each in a rocket ship, just a few feet apart. Assume that the one of the twins (call him "twin 1, or whatever you want) is about to be launched off to a star which is 5 (earth) light years away) at a "crusing" (inertial) speed of .6c relative to earth. Fill in whatever acceleration speeds you think are appropriate for the acceleration experienced during blast off and during "turn-around." Now:
1. Assume that the ship where twin 1 is, in fact, blasted off, and accerlates, travels, turns around, travels, decelerates and lands, while twin 2 just sits on earth in his ship. Now calculate the age of both twins. See what your answer(s) are, and compare them. Then...
2. Do the same problem (to the same star at the same rates of travel, acceleration, etc.,) but simply assume the ship in which twin 2 is sitting accelerates this time, while the ship remains motionless.
A. Which, if either, twin is younger in case 1? By how much?
B. Which, if either, twin is younger in case 2? By how much?
I would think the answers would be identical (in reverse), but what the hell do I know?
Now, first, pretend that ship #2 is really "earth" and that I just called it a "ship" to avoid any complications resulting from differing masses, etc.
Is it in any way that paradoxical that each twin is "younger than the other" simply because the one who moved is younger in each case? Not to me, it isn't.
What is paradoxical is any claim that the differing twins aging differently in the two cases results from MERELY RELATIVE motion. The difference is easily explained by the fact that the motion is not "merely relative." In each case, a different twin is intrinsically moving with respect to his brother, who, relative to his brother, is motionless.
Nonetheless (or "therefore") the wiki paradox remains unresolved. wiki: "How can an absolute effect (one twin really does age less) result from a relative motion? Hence it is called a paradox."
It should be obvious, but I meant to expressly say, in the last post, to use GR, not SR, assumptions and calculations.
I said: "See my prior post on this. Can you point out even one place where wiki says, or even remotely indicates, that "in this solution, we are addressing the solution where Stella is stationary?" It says no such thing, that I've seen (for the reasons stated above)."
I should note that, amidst all the "travelling twin" and "stay at home" twin talk sandwiched around it in wiki, there is this statement: "Now the accelerated frame is regarded as truly stationary"
I'm still not sure what that is supposed to mean, because at first it seems contradictory to say that an "accelerated frame" is "stationary." On the other hand, as I understand it, an object is "accelerated" if is not inertial (i.e,. if it is not moving merely in accordance with it's own "natural" motion, free from external forces). so if, in the "Stella with her thrusters" example, Stella is "motionless" at turn-around, she is nonetheless "accelerated." So is that the "accelerated frame which is regarded as stationary" at turn-around?
Again, the wiki statement is simply: "Now the accelerated frame is regarded as truly stationary." Another way of reading this is that the accelerated twin (Stella, who blasted off from earth) is "treated" (scarequotes intended) as "truly" stationary at turn-around. The whole meaning of the statement is of course modified by the qualification which shortly follows, i.e.:
"It should be emphasized that according to Einstein's explanation, this gravitational field is just as "real" as any other field, but in modern interpretation it is only perceptual because it is caused by the traveling twin's acceleration."
So wiki is clearly NOT saying that the "modern interpretation" would ever regard her as "motionless" anyway.
I can't resist. A couple more direct quotes from wiki, together with snarky comments thereon:
1. "The effect [of time dilation due to speed] has been verified experimentally using precise measurements of clocks flown in airplanes."
You should inform them, Eric, that NO such verification has in fact occurred, for the reasons you gave above.
2. "Einstein, Born and Møller invoked gravitational time dilation to explain the aging based upon the effects of acceleration.[4] Both gravitational time dilation and special relativity are needed to explain the Hafele-Keating experiment on time dilation using precise measurements of clocks flown in airplanes."
So, the attempts of Einstein, Born, and Moller notwithstanding, it appears that GR (gravitational) effects alone cannot explain the time distortions observed. There are, in fact, two separate and distinct phenomena, each with it's own distinct effect.
To repeat: "Both gravitational time dilation and special relativity are needed to explain the Hafele-Keating experiment."
Well, that's not the revelant sense for this problem. The "fundamental" principle in question, which I have been stating all along is simply that, according to both SR and GR (both of which could be utterly wrong, for all I know), *some* time dilation is imputed to moving objects, due to motion alone. No such time dilation is imputed to motionless objects. If one object is moving faster than another from any perspective you choose, then the one moving faster will experince greater time dilation.
Any time dilation (or contraction) is relative to some other frame of motion. Since you can say any body is motionless simply by adjusting your coordinate system, it makes no sense to say that time dilation/contraction occurs only on moving objects, except in the sense that their time is dilated/contracted with respect to the the reference frame you have chosen arbitrarily as the default reference frame.
It can never give one answer which is "true" or "accurate" from ALL possible perspectives.
Exactly. The answers you get in SR/GR/LR will always be different in different perspectives (that is, in different inertial reference frames).
Number one: The GR crap is not a "resolution" to the SR problem, and it does not "solve" the SR question even if you can get the same answer.
Not "can" get. Can only get. Do get. Must get. Will get. It's not a trick you make happen, it's the inevitable outcome, because the GR solution is the SR solution in a different coordinate frame with the same ending inertial state.
But none of the above need even be said, so far as the wiki problem goes. In wiki, the issue of who's really moving is NOT even an issue, and it is not ambiguous or subject to dispute.
Nor is it relevant. Also, why are you reverting to using the term "really moving" after telling me that's not what you mean? What do yo mean when you use that term? Can you define really moving, or what ever it is you mean, in a way that is something other than "change in inertial conditions"?
In the wiki set-up for the twin paradox problem, the question of who is "really" moving is posited in the very first sentence. There is no call or reason to argue about what it is, because it is clearly set forth at the very outset. I repeatedly urged you to pay attention to this.
I generally don't watch the guy seling beer at a baseball game. The notion of who is really moving (at least, until you actually define what it means to be really moving) is a distraction, not a part of the problem itself.
They are taking a case where the earthtwin turns out to be "really older," that's all (remember, under GR, you can make the earth twin really older, or really younger, depending on which SR answer you want to make it equal).
Naturally, because the GR answer is the SR answer, under a different coordinate frame that has the same final inertial state.
You refused to consider or acknowledge any of these points. You just tried to use the (conflated) "answer" given by Einstein to imply false claims about the effect of time dilation motion imposes, which is a fundamental assumption of both GR and SR.
I don't think you can find any false claims I have made on this issue, and it's hard to consider what you mean by really moving when you still won't define it. You assert something must be really moving, even if we can't figure out which which object is really moving, except the spaceship twin is aging less, so the spaceship twin must be the one really moving, then complain I am not taking your position seriously.
So, if you could define really moving, this would be a good start.
In addition to everything already said, the SR problem requires an SR solution (if there is one, and, as I have said, wiki never even gives one). "The standard textbook approach" as given by wiki, does indeed require acceleration, but not to solve the problem. It uses it for two purposes:
1. To show that one is "really moving" (changed inertial frames) so that it is "really" the ship twin who is younger, because it was that twin that moved, and
2. To totally remove the apparent paradox from the realm of SR, since SR does even not address accelerated motion
Naturally, because the GR answer is the SR answer, under a different coordinate frame that has the same final inertial state.
This "always be equal" stuff is just plain false, for many reasons which I have already stated. I will repeat two of them here:
1. For any answer you can create an "equal" result, I can create virtually an infinite amount of made-up circumstances which will give an unequal result where Stella does not age less by the exact same amount.
However, anytime you create a made-up circumstance where the experiences of Astro/Eartha (or any new pair) corform exactly to the experiences of Stella/Terence with regard to perceived relative motion and change in intertial environments, and end that scenario in the common final inertial condition of Stella/Terence, you will get the exact same aging differences. No matter how you change it or what the changes look like, if those two conditions hold, the age differences will be identical.
2. As said above, if, in SR, the earth is treated moving, the earthtwin will be younger, not older. You can then use a GR analysis to get an "equal" answer i.e., that Terrence is younger. That is the complete opposite of your claim that "Astro/Stella will age less than Eartha/Terence by the examct same amount in the exact same manner." In my counter-scenario, Stella does NOT age less, she ages more.
In the scenario where the earth is undergoing propulsion, using primes to distinguish these characters from the standard characters, the experiences of Stella' do not match those of Stella, nor do the experiences of Terence' match those of Terence, so naturally their answers are different. Astro/Eartha match Stella/Terence because they experience the same thing.
All kinds of special assumptions are built into your "will always give equal answers" approach.
Actually, those are necessities that flow out of the one basic condition I need to fulfill: the experience of Astro/Eartha needs to be identical to that of Stella/Terence with regard to relative motion and changes in the inertial environment. That's been the point of the example all along.
Yes, indeed I was seeing "gravitional forces" as being relevant to the SR problem--they aint there. Once again, you simply conflate two distinct concepts (SR & GR) into "one" and call it all "relativity." For our purposes that distinction was crucial, as was the distinct between gravitational contraction and "speed" dilation.
The distinction, however crucial you may feel it to be, it also fictional. SR is a part of GR. It's like discussion the function of the heart, but saying you want to leave the curculatory system out of the discussion. If you try to draw any conclusions at all from the action of the heart that go beyond the heart in any way, and you don't consider the circulatory system, you'll probably get the wrong answer.
You can discuss what SR says about the twin paradox by just looking at SR, no problem. However, you want to do more. You have said that the SR solution involves some notion of who is really moving that seems to go beyond a change in inertial reference frames, even thought there is no way to talk about this concept in SR beyond the change in inertial reference frames. If you want to start adding concepts to SR, these concepts also need to fit inside GR, or the concept is not going to be appropriate.
I'm interested in an analytical discussion, not evasive "verbal combat."
OK, but I also assume you are interested in discussing the theory as it is understood and empirically tested, and not some other-universe alternative to it.
See my prior post on this. Can you point out even one place where wiki says, or even remotely indicates, that "in this solution, we are addressing the solution where Stella is stationary?"
From the three paragraphs referenced before, and note it ieven uses the word "stationary":
"...how the traveling twin perceives the situation...from the viewpoint of the traveler...Now the accelerated frame is regarded as truly stationary...When an observer finds that inertially moving objects are being accelerated with respect to themselves, those objects are in a gravitational field insofar as relativity is concerned...So it could be called the "accelerated observer viewpoint" instead".
One Brow: Assuming you are serious, what is the difficult part?
I'm not serious, and you probably realize if you read what I said about a mongoloid idiot.
I specifically asked which of several items were confusing you. Was it that you can adopt different coordinate systems to describe that same event, that in one such arbitrarily chosen coordinate system the plane and its clock are stationary, or that even after adopting different coordinate systems, the same result pops out?
If, in SR, you assumed the ship twin was the one moving, then SR would say the ship twin was 5.14 years younger, and, if you are right, then GR would agree! But, alas...
If, in SR, you assumed the earth twin was the one moving, then SR would say the earth twin was 5.14 years younger, and, if you are right, then GR would agree!
GR does not solve the paradox.
I am interpreting "the one moving" to mean "the one that changed inertial reference frames" for now. You are describing two different variations of the one paradox. Why would the answers be the same? Is there any reason 2 - 5 would equal 5 - 2? Your comparison of #1 and #2 is like insisteng subtraction be commutative.
Of course, maybe in your back packet somewhere you will pull out a definition of what you mean by "the one moving".
Nor does it give the "same" answer as SR, because, as all authors say, SR does not give ANY answer.
Nonsense. SR gives you answers in both #1 and #2. Because #! and #2 describe different relativistic conditions (agsin under my presumpiton of what you mean by moving), there is no reason they would have the same answer.
1. GR "solutions" are not the same (in number of years aging, etc.) as SR solutions to a given problem, in any event.
Except, they are and must be the same.
2. Trying to match SR calculations with GR calculations by, as Einstien did, by inventing totally bogus "forces" is NOT giving the "same" answer to the "same" problem. All the assumptions have changed from SR, so it cannot be the SAME problem, even if you can rig it to reach the so-called "same" answer.
What you are seeing a bogue forces is really the result of using different coordinate systems.
All GR ends up giving you is a huge "time gap."
Where? At what point? You could say that GR notions close a time gap that a naive use of SR in a differing inertial frame leaves open.
One Brow said: "This is why there can never be an answer to whether Pat or Chris is younger without first specifying a reference frame,. and since all reference frames are arbitrary choices, there can never be a definitive answer to which is younger."
Then you still don't understand the simple points that I have already pointed out at least, now, 16 FUCKING times.
Then, if you really have a point to make and defend there, let's limit the discussion to that point. What is that point?
Frankly, I find it more likely I have understood your point ans dismissed it as being a hopelessly naive understanding of the events, but I could be wrong.
I haven't even tried to figure out what you mean by this. The whole situation relates to Pat and Chris, not Stella, so I won't bother.
There are no isolated motion effects in Pat/Chris, because all motion is relative. There are only relative motion effects.
I've already made a lot of (presumably unread) posts on this whole topic. If after reading them (and I hope at least trying to understand them) this is still an issue for you, let me know.
I have read every word. I have not responded to every word, because a lot of it was in support of examples that had fundamental flaws in it's thinking.
To begin with, first assume that two twins are next to each other, ...I would think the answers would be identical (in reverse), but what the hell do I know?
In that situation, you are correct as far as I can tell, to the degree any two people light-years apart can be looked at simultaneously. You can get an answer here because at the start and the end of the problem, these two twins are in the same inertial framework.
Now, first, pretend that ship #2 is really "earth" and that I just called it a "ship" to avoid any complications resulting from differing masses, etc.
Is it in any way that paradoxical that each twin is "younger than the other" simply because the one who moved is younger in each case? Not to me, it isn't.
I assume you meant "either twin could be younger than the other", and I agree.
What is paradoxical is any claim that the differing twins aging differently in the two cases results from MERELY RELATIVE motion.
Paradoxical or not, this is true.
The difference is easily explained by the fact that the motion is not "merely relative." In each case, a different twin is intrinsically moving with respect to his brother, who, relative to his brother, is motionless.
Sorry, that sentence is devoid of meaning in an SR framework, unless you mean that one twin changed inertial environments and the other did not. Of course, I acknowledged that several hundred comments ago.
It should be obvious, but I meant to expressly say, in the last post, to use GR, not SR, assumptions and calculations.
I haven't been able to actually do that for years. I remember the basics and the broad strokes, but I would have to study tensor calculus for two-three months to do the calculations directly. Besides, since we are dicussing linear motion in an intertial coordinate system, it would just boil down to the SR calculation anyhow.
I'm still not sure what that is supposed to mean, because at first it seems contradictory to say that an "accelerated frame" is "stationary." On the other hand, as I understand it, an object is "accelerated" if is not inertial (i.e,. if it is not moving merely in accordance with it's own "natural" motion, free from external forces). so if, in the "Stella with her thrusters" example, Stella is "motionless" at turn-around, she is nonetheless "accelerated." So is that the "accelerated frame which is regarded as stationary" at turn-around?
Not just at turn-around, but at every part of the journey.
So wiki is clearly NOT saying that the "modern interpretation" would ever regard her as "motionless" anyway.
Of course not, because that would violate conservation of mass-energy. Treating Stella as stationary is an exercise in changing coordinate systems and using gravitation to explaing the effects observed.
I can't resist. A couple more direct quotes from wiki, together with snarky comments thereon:
You've been tryingto make points and understand this for quite a while. A little snarkiness between old acquaintances is no big deal.
You should inform them, Eric, that NO such verification has in fact occurred, for the reasons you gave above.
You mean, because we can perform a change of coordinates that allows for an alternate explanation that defies the conservation of mass-energy?
2. "Einstein, Born and Møller invoked gravitational time dilation to explain the aging based upon the effects of acceleration.[4] Both gravitational time dilation and special relativity are needed to explain the Hafele-Keating experiment on time dilation using precise measurements of clocks flown in airplanes."
So, the attempts of Einstein, Born, and Moller notwithstanding, it appears that GR (gravitational) effects alone cannot explain the time distortions observed. There are, in fact, two separate and distinct phenomena, each with it's own distinct effect.
To repeat: "Both gravitational time dilation and special relativity are needed to explain the Hafele-Keating experiment."
Gravitational time dialation and special relativity are both features of GR. In the preferred coordinate frame (a fixed point on the surface of the earth) both effects come into play. However, you can choose other coordinate systems where only one effect or the other will be active.
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