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 1001 – 1200 of 1677 Newer› Newest»Suppose a guy steps off the top floor of the Empire State Building. From our perspective, he falls for a spell, and then busts his head on the sidewalk like a cantalope being hit by a 50-pound sledge hammer being swung by a powerful machine.
From another frame of refence it might look like the guy was moving before stepping off, but was absolutely motionless once he stepped off, and then the earth came up an busted his sorry head. Does that mean the other frame of reference "could be" right as a practical matter (not a just a wholly theoretical and subjective matter)?
If your answer to this is "yes, that's what it means as a practical matter," does that mean both viewpoints are true, or that neither is true? Is your basic claim that nothing is true if someone can see it from a different perspective (and hence, literally that NOTHING is true)? If that is your conclusion, is it based upon the "truth" of SR and GR, or what? If so, why would you think they were true? NOTHING is true, remember? There is a different perspective (LR, for example) from which all events interpreted by SR can be interpreted, ya know?
I saw a guy on the net trying to give the "true" resolution of the twin paradox in the same inconsistent manner in which you do, Eric. In essence he said there is no paradox because....because there really IS a paradox, that's why!
1. The "paradox" began with this observation (more or less). IF all frames of reference are equally valid, then it would be equally valid for each to claim that he is the one who is younger (older, whatever). It would be a logical contradiction, a paradox, to say that each "really is" younger than the other.
2. This original paradox was resolved by saying the two frames of reference are not equivalent, and therefore equivalent results cannot be demanded. Despite some of the attempts at obsurantist terminology and nomenclature, the bottom line of this "resolution" was: Because the ship twin is the one who "really turned around," he is the one really moving, and the earth twin does not have an equal claim to being called the one "really moving" because he did not experience the inertial forces required by a turn-around.
3. However, this just created a new form of paradox....
The new paradox was this: Well, so now you have provided a way in which to empirically detect which of two objects is "really moving." Just look at the clocks of each. Whichever one has recorded less time is the one who was "really moving." So don't say motion can only be relative and undetectable in such a way as to attribute motion to one of two relatively moving objects. Hmmm, what now, for the relativist?
Many physicists and mathematicians beleived that, in some manner yet to be explained, the effects of acceleration were such as to offset the time differnce given by SR. The idea was that once you had a theory that was sufficient to show how ALL motion is relative, including accelerated motion, the effects of acceleration would be shown to cancel the time difference given by SR alone. Once that was done, it would be shown that there was no real aging difference, just the appearance thereof while in relative motion. The idea was that the new theory would demonstrate that, once re-united, the two clocks would read the same.
This just didn't work out, notwithstanding Einstien's best efforts in his dialog to show that the results were "equivalent" to each other.
The supposed "equivalency" in his example is completely bogus and misleading, but even if it were valid it merely reinforced the assymmetry. No matter which one was moving, one would always show a time difference from the other. And that time difference didn't even depend on which one was moving (which contradicts SR, which says the moving clock will run slower in each and every case).
Hmmm, now what?
The only course left, it seems, is to take the one you have taken.
1. Deny the validity of the expermential evidence. Deny that a clock in orbit "really is" running slower because it "really is" going faster. Deny that acceleration adds nothing to time dilation, as shown by experience, and resurrect Einstien's argument, while ignoring the inherent defects in it's reasoning.
2. After denying all evidence, now state that each clock REALLY IS running slower than the other. When it is pointed out to you that this is a paradox, DENY that it is a paradox.
3. Now, to refute even your own reasoning, further deny that it is even POSSIBLE for one clock to run slower than the other.
Purty simple, actually.
There is no paradox within SR itself. It merely says that clocks which are "really" going faster will "really" run slower.
The paradox only comes in when someone tries to insist that SR "proves" an ontology which is inconsistent with the clear dictates of SR and with the the experiments which confirm those predictions.
The "Doppler analysis" proves nothing. It doesn't say, "well, look, the doppler effect can explain all this." On the contrary, the doppler analysis is merely ADDED to the the predictions of SR (which say that the one really moving will be the one who really ages slower--it too assumes that the ship is the one which "really turns-around" and that the ship twin is therefore the one who is really moving.
Just think about the implications of what you like to think of as Einstien's "resolution" of the paradox.
1. One clock will always be slower. It will always the the same clock--call it the "clock on the right"--regardless of which clock is "really moving." So now we have the same difference, but are deprived of any and all rational reason for there to be a difference. At least SR said it would be a particular clock DEPENDING on an observable event (really moving). Einstien appears to deny even this--which again contradicts SR, if true, and "explains" nothing. It creates millions of questions requiring an explanation while explaining nothing about the paradox. Had he been able to show that the clocks would read the same in either case, he might have had something, but...
One Brow said: "In both frames K and K', clock U1 is inertial at all times."
Do you even read this stuff, Eric? All of these excerpts are from frame K': "Clock U1 is accelerated in free fall, until it has reached velocity... Clock U1 is accelerated in the direction of the positive x-axis until it has reached the velocity v...A gravitational field that is directed towards the negative x-axis appears and brings U1 to a halt." See the word "accelerated," there? See the phrase "brings U1 to a halt?"
This is why I didn't even want to get into confused terminology with you. This excerpt from wiki:
"Einstein's concept of inertia remained unchanged from Newton's original meaning (in fact the entire theory was based on Newton's definition of inertia). However, this resulted in a limitation inherent in Special Relativity that the principle of relativity could only apply to reference frames that were inertial in nature (MEANING WHEN NO ACCELERATION WAS PRESENT). In an attempt to address this limitation, Einstein proceeded to develop his theory of General Relativity ("The Foundation of the General Theory of Relativity," 1916), which ultimately provided a unified theory for both inertial and noninertial (ACCELERATED) reference frames."
http://en.wikipedia.org/wiki/Inertia#Relativity
You can't even seem to read a simple paragraph for what it says. It can never say anything to you which is not consistent with your own personal interpretation of your own *special* definitions. You previously said: "One Brow said: "By the EP, free-fall is inertial, and resisting gravity is acceleration." All Einstien has to do is throw in the word "free-fall" and all your common sense seems to go out the window for you. My response was:
"We can put a rocket in free-fall (orbit) but ONLY IF we first accelerate it. It doesn't go directly from it's "motionless" state on the launching pad into full blown "free fall." That only comes later AFTER extreme (and extremely noticable) acceleration. How can this guy (clock) in Al's example go from a state of "rest" to, say .99c INSTANTLY, without accelerating first?
Acceleration, whether caused by gravitation or observable physical forces, is still acceleration."
Free fall is NOT incompatible with acceleration. Anything being accelerated is NOT in an inertial state.
"Free fall describes any motion initiated solely by the force of gravity."
http://en.wikipedia.org/wiki/Free-fall#Free_fall_in_Newtonian_mechanics
Clock U1 is accelerated, it is therefore not in an inertial state, EVEN IF it is in "free fall."
As I suspected, you math answers to your own questions assume the very premises I thought we were trying to discuss. They make unwarranted assumptions, one of which I will address in more detail below and seem to violate the premises of the very question you posed.
I don't really wish to discuss them further, as math problems, at this time. The whole scenario is eerily reminiscient of the time you presented some computer simulations of a mathematical formula which merely incorporated your mistaken premise, which premise you admanantly refused to reconsider, based on the simulations.
The idea behind discussing a conclusion, Eric, is NOT to continously assume and re-assert it. Keep your conclusion in your mind, that's fine. But be willing to discuss the premises, logic, and theoretical and factual assumptions upon which you are basing it. You seem virtually incapable of doing that.
I'm beginning to think that your idea of a "good debate" would be watching two five years olds argue where one screams "Is so!" then the other screams "Is not!" about a thousand times.
After doing your math computations (some of which plainly appear to wrong, but, I'm not gunna get into that right now), you ask this:
One Brow said: "Care to comment on how you can say one is absolutely younger than the other before the acceleration events?"
The question is, do YOU care to comment on it? I already have, at some length, and can do so again, if necessary. But your math problems don't address it in the slight bit and are totally irrelevant to that question.
I said: "They would age the same amount after the commencement of "future event three," but that could in no way retroactively change the prior age difference (if any)."
You replied; "To the extent you can discuss a prior age difference at all, there would be none."
As usual, your "comments" are confined to flat, unsupported conclusions. I dispute, and disagree with, you conclusion (it's possible, but not necessary, as you imply, that "there would be none'). So I want to know how and why you think you are entitled to make this claim.
SR says both would perceive the other to be younger, right? You are saying there IS no age difference. Why do you say that? How is it consistent with your prior claims to the effect that time REALLY DOES slow down with higher speeds?
One Brow said: "The wiki example never says that one twin is going faster than the other twin."
ARE YOU SERIOUS? Does this claim reflect your standards for "honest debate," or does it reflect your total inability to draw the most inescapable inferences unless and until they are expressly pointed out to you?
As I recall, the wiki example explicitly posits that:
1. The earth twin stays home (remains motionless) while
2. The ship twin spends over 10 (earth) years going at a the higher relative rate of speed of .6c
Are you claiming that a rate of speed of .6c is NOT "faster" than a rate of speed of 0?
One Brow said: "If you want me to keep answwering these questions, you need to answer this one: If you have two objects X and Y moving at relative speed v to each other, X sees Y moving at v, and Y sees X moving at v. So, how can one be "faster" compared to the other?"
I can't even understand why you think this is a question, except insofar as it contains implicit assumptions that I think are totally unsound.
Do you think that what one sees limits what "can be?"
One Brow said: "If you want me to keep answwering these questions, you need to answer this one: If you have two objects X and Y moving at relative speed v to each other, X sees Y moving at v, and Y sees X moving at v. So, how can one be "faster" compared to the other?"
To answer your question more directly--I still want an answer to mine (do you think what one "sees" limits what "can be?)--Both X and Y assume that they are at rest and that the other is "really moving," and, needless to say, also "moving faster." That is why they "see" what they "see." But both cannot simultaneously be "at rest" unless all motion is illusory. Therefore at least one must be really moving, their mutually contradictory assumptions nothwithstanding. Who is moving faster may be unknown.
You assume you are facing north and therefore that east is on your right. I assume that I am also facing north and agree with you that east is "to the right." However, we are back-to-back, facing opposite directions at the time. Who is right? Both of us? Neither of us? Are we "equally right?"
I said: "Both X and Y assume that they are at rest and that the other is "really moving," and, needless to say, also "moving faster." That is why they "see" what they "see."
If both agreed that X is "at rest" and that Y is the only one who is "really moving," then, if they are familiar with SR principles and mathematics, they would agree that one is "really" younger and by how much. This is what happens in the wiki example. The fact that they don't agree the as you posed the question is because at least one of them is just flat WRONG.
Your principle of relativity basically says:
1. Each is equally entitled TO ASSUME that he is at rest.
Assumptions do not create reality.
You have unconsciously transmuted this into: "Each IS at rest," (because he is equally entitled to assume that he is)
Or, in the alternative, "because each is equally entitled to assume he is at rest, it would be "unfair" to say that one is not really at rest."
But what you are "entitled to say," as a PC matter, has nothing to do with what actually IS.
I aksed: "Suppose it was later discovered that, 6 years ago, P was accelerated, from a planet at rest relative to C, to the speed of .5c."
You answered: "Changing the scenario allows you to get different answers, certainly."
Thank you. You probably don't know it, but you have finally acknowledged the simple, and easily understood, point I have been trying to get you to see all along.
I didn't "change the scenario" at all. I just gave you more information about the scenario than you had before.
You were saying that it was NOT POSSIBLE for one to be going faster than the other.
What you meant (but have consistently denied that this is all you meant) was that it is not possible for us to know (given our presently limited knowledge of the situation) which one is going faster. But you continue to treat two radically different statements as 100% identical, i. e.:
1. It is impossible for me to answer question X (epistemological deficiency).
EQUALS
2. It is impossible for there to be an answer to question X (ontological claim).
I said: "1. Each is equally entitled TO ASSUME that he is at rest.
Earthtwin (ET) and shiptwin (ST) ask the relativist: You really mean that!?
Relativist (R): Sho nuff.
ET: So I can claim I was at rest the whole time, and that ST was the one who was really moving away from me at .6c?
R: Sho nuff
ST: So I can claim I was at rest the whole time, and that ET was the one who was really moving away from me at .6c?
R: Fraid not.
ST: But you said...
R: Don't count, what I said before.
ST: Why not?
R: Because you were the one really moving. It don't count when you're really movin, see? Ya ignorant slut, ya.
I said: "You assume you are facing north and therefore that east is on your right. I assume that I am also facing north and agree with you that east is "to the right." However, we are back-to-back, facing opposite directions at the time. Who is right? Both of us? Neither of us? Are we "equally right?"
I took this dilemna to my great-granddaughter, who teaches kindergarten. I sez: Looky, here, ya got two kids, one facing west and pointing north with his right hand, and another, facing east pointing south with his right hand, each claimin they are pointin east. How do ya settle this?
She sez, Granpappy, looky here, it aint no thang. Both are equally entitled to assume they are facing north, and assuming they are facing north they are BOTH right! They are right that east would be on their right, see? There simply is no wrong answer here, it would be impossible for either to be wrong. East is any direction you point. There is no real east. That usually gets them to settle down and quit saying "is so!" and "is not!"
One Brow said: "Assuming the conservation of energy, the earth is moving."
Now ya done gone and done it again, eh, Eric? Ya cheated the earth out of it's "equal right" to assume it's at rest. It just aint no kinda fair, I tellya!
There seem to be some very basic misconceptions here. I am only responding to a small part of what you wrote, until these can be cleared up. Once we can do that, I believe you will see why much of this was irrelevant. In particular, I will be ignoring any attempts to argue that speed must be absolute because something like east is absolute. Arguments from that analogy just don't work.
From another frame of refence it might look like the guy was moving before stepping off, but was absolutely motionless once he stepped off, and then the earth came up an busted his sorry head. Does that mean the other frame of reference "could be" right as a practical matter (not a just a wholly theoretical and subjective matter)?
This depends upon what you mean by "as a practical matter". In relativity theory, you can't tell the difference between the two. There are many other aspects of physics you can use to say he fell to the earth rather than the earth rising to him, but they do not exist in relativity theory.
If your answer to this is "yes, that's what it means as a practical matter," does that mean both viewpoints are true, or that neither is true?
It means relativity theory does not say one is true or the other.
Is your basic claim that nothing is true if someone can see it from a different perspective (and hence, literally that NOTHING is true)?
I have said, repeatedly, that there are other means besides relativity theory to say one is true. One method I have referred to repeated is the conservation of energy. If you persist in thinking that relativity theory must be used to find some answers it simply can't find, you are in for a great deal of fgrustration. If you persist in saying that, since I am saying these answers are not available in relativity theory, I am saying they are not available at all in physics, you merely make yourself look like a jerk.
The new paradox was this: Well, so now you have provided a way in which to empirically detect which of two objects is "really moving." Just look at the clocks of each. Whichever one has recorded less time is the one who was "really moving." So don't say motion can only be relative and undetectable in such a way as to attribute motion to one of two relatively moving objects. Hmmm, what now, for the relativist?
The one who experienced the non-inertial environment was "really moving".
One Brow said: "In both frames K and K', clock U1 is inertial at all times."
Do you even read this stuff, Eric?
Not only do I read it, I understand it. You don't.
All of these excerpts are from frame K': "Clock U1 is accelerated in free fall, until it has reached velocity... Clock U1 is accelerated in the direction of the positive x-axis until it has reached the velocity v...A gravitational field that is directed towards the negative x-axis appears and brings U1 to a halt." See the word "accelerated," there? See the phrase "brings U1 to a halt?"
Yes, I saw it all, I understand it all. What you fail to grasp is that when you are "accelerated in free fall" you are in an inertial environment, and this contues to be a struggle for you. Men on the space station are in an inertial environment. If they hold a ball still in front of them and then let it go, the ball doesn't move relative to them. To an observer on Mars, both the men and ball are undergoing acceleration. To the men on the space station, their environment in empirically inertial. In coordinate system K', the environment of U1 is still inertial, and while the environment of U2 is not. Until you understand why this is, and even must be true (since inertai is not coordinate-system dependent and K' describes the same events as K), you will not understand what is going on.
This is why I didn't even want to get into confused terminology with you.
This is a hindrance for you, AFAICT. Sometimes terminology can confuse more than it helps, but sometimes it actually brings clarity.
Acceleration, whether caused by gravitation or observable physical forces, is still acceleration."
There is an empirical difference between acceleration by propulsion and one by free-fall, and it is that in the second case, your environment is inertial. You experience no effects of acceleration.
Clock U1 is accelerated, it is therefore not in an inertial state, EVEN IF it is in "free fall."
You are simply wrong here.
As I suspected, you math answers to your own questions assume the very premises I thought we were trying to discuss.
So, you ask for the math and then refuse to examine it in detail. How expected.
After doing your math computations (some of which plainly appear to wrong, but, I'm not gunna get into that right now)
No, let's get into it. It would do you some good.
One Brow said: "Care to comment on how you can say one is absolutely younger than the other before the acceleration events?"
The question is, do YOU care to comment on it? I already have, at some length, and can do so again, if necessary. But your math problems don't address it in the slight bit and are totally irrelevant to that question.
I have commented on this at some length as well. The question of who is younger will be viewpoint-dependent, empirically. PV will see them as the same age. to the exgtent there can be an ontological answer, they are the same age because both environments are inertial.
I said: "They would age the same amount after the commencement of "future event three," but that could in no way retroactively change the prior age difference (if any)."
You replied; "To the extent you can discuss a prior age difference at all, there would be none."
As usual, your "comments" are confined to flat, unsupported conclusions. I dispute, and disagree with, you conclusion (it's possible, but not necessary, as you imply, that "there would be none'). So I want to know how and why you think you are entitled to make this claim.
SR says both would perceive the other to be younger, right? You are saying there IS no age difference. Why do you say that? How is it consistent with your prior claims to the effect that time REALLY DOES slow down with higher speeds?
Why, I did that quite a while ago, upon your insistence that there must be some metaphysical indicator. The only reasonable metaphysical indicator is that time moves at it maximal speed within inertial environments, or if you like, you always go through the most time when your environment is inertial. In any form of the twin pardox, the inertial environment twin ages the fastest. Since Pat and Chris are both in inertial environments, they are the same age, using that guideline.
One Brow said: "The wiki example never says that one twin is going faster than the other twin."
ARE YOU SERIOUS? Does this claim reflect ...
It reflects the actual contents of the wiki page, which you fail to understand in part because you don't want to give up your pet termininology. The wiki page never talks about an abosolute relative speed, one person going fater than antoher without a third reference frame, or any of the other non-relativistic notions you keep tryingt o bring into relativity.
2. The ship twin spends over 10 (earth) years going at a the higher relative rate of speed of .6c
Are you claiming that a rate of speed of .6c is NOT "faster" than a rate of speed of 0?
It does terms that could mean "relative rate of speed". It does not use anything that means '"faster" than a rate of speed' or 'higher relative rate of speed'.
One Brow said: So, how can one be "faster" compared to the other?"
To answer your question more directly--I still want an answer to mine (do you think what one "sees" limits what "can be?)--
What one sees does not limit what can be.
Both X and Y assume that they are at rest and that the other is "really moving," and, needless to say, also "moving faster." That is why they "see" what they "see." But both cannot simultaneously be "at rest" unless all motion is illusory. Therefore at least one must be really moving, their mutually contradictory assumptions nothwithstanding. Who is moving faster may be unknown.
That was a nice try, but the question was, "how can one be "faster" compared to the other?" I have repeated said that you can always bring in a third reference frame to determine who is moving fater with respect to that reference frame. If you are not comparing them to each otherm, and you are not comparing them to a third reference frame, what does it mean to be "moving faster"?
I aksed: "Suppose it was later discovered that, 6 years ago, P was accelerated, from a planet at rest relative to C, to the speed of .5c."
You answered: "Changing the scenario allows you to get different answers, certainly."
Thank you. You probably don't know it, but you have finally acknowledged the simple, and easily understood, point I have been trying to get you to see all along.
I didn't "change the scenario" at all. I just gave you more information about the scenario than you had before.
You were saying that it was NOT POSSIBLE for one to be going faster than the other.
1. The initial scenario was that Pat and Chris were born in close spatial proximity in different inertial environments. Saying they were in the same iniertial environment six months ago is changing the scenario.
2. Nothing about your change says Pat is now going faster than Chris.
3. Let's adapt the scenario to include your change. Pat and Chris were born in the same inertial environment, and six month ago Pat was accelerated to .6c compared to Chris. Let's say pat and Chris are both exactly 12,000 days old, as they have each experience time, when they are close to each other. In that case, at the end of future sceanioro 1 (as laid out in comment #999), Pat will be 12,016 days old when Chris is 12,020 days old. In future scenario 2, Pat will be 12,020 days old when Chris is 12,016 days old. In scenario 3), both will be 12,016 days old. Your added input does not change what will happen.
So, how is one "moving faster" than the other?
One Brow said: "Assuming the conservation of energy, the earth is moving."
Now ya done gone and done it again, eh, Eric? Ya cheated the earth out of it's "equal right" to assume it's at rest. It just aint no kinda fair, I tellya!
Conservation of energy is not a concept in relativity.
Eric, there are inconsistencies, contradictions, equivocations, and evasions throughout all of your most recent posts, just as there have been throughout this entire thread. I'm through trying to show you how and why. That would just start another potential 1000 posts with you denying each inconsistency.
One last question:
1. Assume A & B are travelling at .5c relative to each and that each agree on this relative speed.
2. A, as he is entitled to do, given the philosophical grounding of relativity, ASSUMES that he is at rest.
3. B, as he is entitled to do, given the philosophical grounding of relativity, ALSO ASSUMES that he is at rest.
Question: Does either SR or GR claim that it is possible for BOTH to simultaneously be at rest?
I said: "1. Assume A & B are travelling at .5c relative to each and that each agree on this relative speed."
I should have been more specific here. I am talking about accelerated motion, not uniform motion. "Travelling" here means separating from each other, as in the Pat and Chris example. So I should have said travelling away from each other at the rate of .5c, just as in the wiki example where the ship was travelling away from the earth at .6c, or whatever is was.
Forget what I just said about non-uniform motion, I DON"T mean accelerated motion after all, not sure why I even had second thoughts about it. Like the wiki example, but ignore all acceleration involved there.
I said: "Question: Does either SR or GR claim that it is possible for BOTH to simultaneously be at rest?"
Just to avoid some meaningless answer, I mean is it possible IN THESE CIRCUMSTANCES, not some other imaginable circumstances.
Question: Does either SR or GR claim that it is possible for BOTH to simultaneously be at rest?
What do you interpret "at rest" to mean within relativity theory? If all you mean is "in an inertial reference frame", yes they can both be in an inertial reference frame, with relative (i.e., real) motion existing between those frames. If you mean that each can choose an inertial frame where they are not moving, but no inertial frame says both are not moving, I agree and that is something you could say in relativity theory. If you mean at rest with regard to some third, unmentioned inertial frame, such as the frame were the center of gravity for the universe is at rest, then you can say this in relativity, but the way you just said it was incomplete. If you mean anything more than that, you probably can't describe that in relativity theory, but I would like a more precise definition of "at rest" before I say one way or the other.
Sorry, I misspoke:
If you mean at rest with regard to some third, unmentioned inertial frame, such as the frame were the center of gravity for the universe is at rest, then you can say neither (or at most one) is at rest in relativity theory, but the way you just said it was incomplete.
One Brow said: "The wiki page never talks about an abosolute relative speed..."
Wiki: "So the traveling clock K' will show an elapsed time of...
whereas the stationary clock K shows an elapsed time of..."
Eric, if you cannot comprehend the meaning of words like "stationary" and "travelling" then you should get a dictionary and take an English class.
As far as "inertial" goes, wiki says: "Knowing that the clock K remains inertial (stationary)..."
I simply mean that, as between the two of them--forget all other conceivable reference frames for now--A assumes that he is at rest, and that B is the one "really moving" at the rate of .5c B assumes the opposite. Each assumes that he is "at rest" relative to the other.
Again: "As far as "inertial" goes, wiki says: "Knowing that the clock K remains inertial (stationary)..."
You have testified to the validity of the answers given at wiki. How could wiki "know" that one clock remains stationary? On top of that, they are only talking about two objects (two twins), doesn't this make it "impossible" to say that one is going faster? Quibble, equivocate, deny, and re-define terms to your hearts content, but any fool will tell you that an object going .6c is going "faster" than an object going zero (stationary).
I simply mean that, as between the two of them--forget all other conceivable reference frames for now--A assumes that he is at rest, and that B is the one "really moving" at the rate of .5c B assumes the opposite. Each assumes that he is "at rest" relative to the other.
Then yes, each can say individually that they are at rest relative to the other. Neither will say both of them are at rest. Does that answer your question?
You have testified to the validity of the answers given at wiki. How could wiki "know" that one clock remains stationary?
Within relativity theory, it can't. By applying the principle of the conservation of energy, it can.
On top of that, they are only talking about two objects (two twins), doesn't this make it "impossible" to say that one is going faster?
The article never says that one is moving faster than the other in some absolute, not-strictly-relative way. It says you can pick the inertial frame to be the one at rest.
Quibble, equivocate, deny, and re-define terms to your hearts content, but any fool will tell you that an object going .6c is going "faster" than an object going zero (stationary).
Compared to some third object/point/reference frame, where the first is going at .6c with respect to that frame and the second is at rest compared to that frame, certainly. If is not quibbling, equivocation, denial, nor redefinition to say that you have to specify the third frame before you can make that statement, it is essential to the very concept of motion, much less relativity theory. Just because you don't always state it explicitly doesn't mean it isn't there.
One Brow said: "Then yes, each can say individually that they are at rest relative to the other. Neither will say both of them are at rest. Does that answer your question?"
No, it doesn't. The question was NOT about what either particular observer "will say." The question was:
Question: Does either SR or GR claim that it is possible for BOTH to simultaneously be at rest?"
One Brow said: "to say that you have to specify the third frame before you can make that statement, it is essential to the very concept of motion, much less relativity theory. Just because you don't always state it explicitly doesn't mean it isn't there."
To say that you need 3 reference frames to compare two object is "to say" something that no one else says. Where, in the Einstien example you are so found of, did he find it necessary to refer to any 3rd frame to compare the two objects?
Let me put it another way, Eric. Is it POSSIBLE, as a logical and physical matter, for two objects to be moving, relative to each other, EVEN IF you couldn't determine it? You can't seem to make even that simple distinction.
Your definition of "at rest":'I simply mean that, as between the two of them--forget all other conceivable reference frames for now--A assumes that he is at rest, and that B is the one "really moving" at the rate of .5c B assumes the opposite. Each assumes that he is "at rest" relative to the other.'
What does "possible for BOTH to simultaneously be at rest" mean under this definition, if not what each individually assumes?
To say that you need 3 reference frames to compare two object is "to say" something that no one else says.
To say "A is moving relative to B" you need two objects. To say "A is moving faster than B" you need a third object/reference frame that compares to A differently than it compares to B.
Where, in the Einstien example you are so found of, did he find it necessary to refer to any 3rd frame to compare the two objects?
The Einstein example does not refer to one object as moving faster than the other object.
Let me put it another way, Eric. Is it POSSIBLE, as a logical and physical matter, for two objects to be moving, relative to each other, EVEN IF you couldn't determine it? You can't seem to make even that simple distinction.
Relativity theory is entirely about objects moving relative to one another. I don't think you meant to ask what you asked, unless you are very confused about the difference between "moving relatrive to" and "moving faster than".
One Brow said: "Relativity theory is entirely about objects moving relative to one another. I don't think you meant to ask what you asked, unless you are very confused about the difference between "moving relatrive to" and "moving faster than"."
No, it is not "entirely about that" and it seems very few physicists seem to think that, Einstein's best efforts notwithstanding, GR dispensed with absolute motion. I meant to ask exactly what I asked. Can you give me answer, rather than an evading.
I know you like to pretend that you like to pretend that you are an expert on GR and SR, but I am not even asking you these questions for the "SR" answer. I am asking you what is logically and phsycially possible. Do you think whatever answer SR/GR would give is the ONLY POSSIBLE answer?
Can you answer the question, or not? Can you give a simple "yes" or "no" answer?
Note: the question you responded to said NOTHING about "faster" to begin with. Can you just answer the question?
One Brow said: To say "A is moving relative to B" you need two objects. To say "A is moving faster than B" you need a third object/reference frame that compares to A differently than it compares to B.
Yeah, just like you need a giant in the room to say than Deron Williams is taller than Brevin Knight, I spoze, eh?
I asked: Where, in the Einstien example you are so found of, did he find it necessary to refer to any 3rd frame to compare the two objects?"
You claim: "The Einstein example does not refer to one object as moving faster than the other object."
Of course he did. It each frame K and K," he had one frame "at rest" and one moving. Sorry, all your evasion, denial, and tortuous squirming aside, ANY speed (even one millimeter per century) is faster than the speed "at rest."
How many objects and reference frames is Al referring to when he simply talks about "the speed of light," eh, Eric? 3? 2? 1?
What could he possibly be saying, other than something incoherent, in your view, when he claims that "no object can go faster than the speed of light?"
Me: I heard David Locke say on the radio today that Deron Williams is taller than Chrissy Paul. In other words, lil Chrissy is shorter than Deron, eh?
You: HE DIDN'T SAY PAUL WAS SHORTER!!!!
"AintNoThang said: Let me put it another way, Eric. Is it POSSIBLE, as a logical and physical matter, for two objects to be moving, relative to each other, EVEN IF you couldn't determine it? You can't seem to make even that simple distinction.
One Brow said: Relativity theory is entirely about objects moving relative to one another. "
No, it is not "entirely about that" and it seems very few physicists seem to think that, Einstein's best efforts notwithstanding, GR dispensed with absolute motion.
I haven't read anything by physicists who think the theory of relativity is about anyting other than relative motion.
I meant to ask exactly what I asked. Can you give me answer, rather than an evading.
The answer I quoted above was not direct? OK,...
Yes, two objects can be moving relative to each other even if one or both of them can not observe the other.
I know you like to pretend that you like to pretend that you are an expert on GR and SR,
I only claim to be more knowledgeable than you are, based on the content of your posts. That hardly qualifies me for expert status. If I had to name my status, it would be "junior aprentice".
Yeah, just like you need a giant in the room to say than Deron Williams is taller than Brevin Knight, I spoze, eh?
Length is not an inherently relative attribute, velocity is.
Of course he did. It each frame K and K," he had one frame "at rest" and one moving.
How does this equate to one moving fater than the other?
Sorry, all your evasion, denial, and tortuous squirming aside, ANY speed (even one millimeter per century) is faster than the speed "at rest."
I have repeated, several times, that you can argbitrarily choose a reference frame to figure out relative speed. From what I can tell, this has not satisfied you; you seem to be looking for a statement that is reference-frame free. So, when you bring up a thought-experiment based upon the arbitrary selection of various reference frames, it does not support your lack of satisfaction that the choice of reference frame is arbitrary.
How many objects and reference frames is Al referring to when he simply talks about "the speed of light," eh, Eric? 3? 2? 1?
Every possible reference frame, an infinite number of them.
What could he possibly be saying, other than something incoherent, in your view, when he claims that "no object can go faster than the speed of light?"
If you care to check, he'll be saying that no object can exceed the speed of light in any reference frame.
One Brow said: "Length is not an inherently relative attribute, velocity is."
This is your new mantra ("inherently relative") and you seem to think it is saying something meaningful. What does that even mean? Mebbe ya better check with Al before you say length aint inherently relative, eh? That aint what he claims.
You never did answer this question:
One Brow said: "Then yes, each can say individually that they are at rest relative to the other. Neither will say both of them are at rest. Does that answer your question?"
No, it doesn't. The question was NOT about what either particular observer "will say." The question was:
Question: Does either SR or GR claim that it is possible for BOTH to simultaneously be at rest?"
One Brow said: "I have repeated, several times, that you can argbitrarily choose a reference frame to figure out relative speed."
You have not even addressed yourself to the question that was asked, that I can tell. The question we started with was NOT:
1. Which one, A or B, can be said to be moving faster?
That AINT the question, get it?
This is your new mantra ("inherently relative") and you seem to think it is saying something meaningful. What does that even mean?
It means that object A has a length regardless of whether any other objects even exist. However, as you once acknowledged, you can only have a speed relative to another object. Have you changed you mind on that?
Question: Does either SR or GR claim that it is possible for BOTH to simultaneously be at rest?"
What does "BOTH to [be] simultaneously be at rest" mean, given you defined "at rest" as 'I simply mean that, as between the two of them ... A assumes that he is at rest, and that B is the one "really moving" at the rate of .5c B assumes the opposite. Each assumes that he is "at rest" relative to the other.'?
One Brow said: "If you care to check, he'll be saying that no object can exceed the speed of light in any reference frame."
I understand that. I also understood you to say that is IS NOT POSSIBLE for one object to be going faster than another to begin with? Would that include light?
One Brow said: "However, as you once acknowledged, you can only have a speed relative to another object. Have you changed you mind on that?"
I never said that. I said it would be an empirically meaningless concept, and I was only talking about uniform motion to begin with. That is true of every concept. Every concept. Everywhere, every time. No "measurement" has any meaning whatsoever without a context and some kind of contrast. This would include the concept of "length."
That said, I can conceive of length, independent of other objects, and I can conceive of speed, independent of other objects. This is especially true of acceleration. If I was the only object in the universe but was getting constantly buffeted around because of continuous accelerations and decelerations, I would notice the phenomenon, even if I didn't attribute it to a change in motion.
And, in any event, I never said speed took 3 objects to be discerned. If one object keeps approaching me, and keeps getting bigger and bigger until it passes right by me (at its "biggest") and then starts getting smaller and smaller, then I can speak of it's speed, so long as a have a means to estimate or measure both distance and time.
One Brow said: "What does "BOTH to [be] simultaneously be at rest" mean, given you defined "at rest" as 'I simply mean that, as between the two of them ... A assumes that he is at rest, and that B is the one "really moving" at the rate of .5c B assumes the opposite. Each assumes that he is "at rest" relative to the other.'?
What does Einstein mean when he says "at rest?" Is your the only answer left in you bag of tricks one which says: I can't understand a word you're saying, even if I can understand the same thing perfectly if anybody else says it?
A: My speed is ZERO, B's is .5c
B: My speed is ZERO, A's is .5c.
Does SR or GR allow for the possibility, that, under these circumstances, A's speed really is ZERO and, at the same time, B's speed really is ZERO?
Yes, or no?
Put another way, does SR/GR allow for the possibility that all motion is pure illusion and posit that 2 objects only (falsely) perceive apparent motion between themselves when, it fact, both objects are absolutely motionless?
Absolutely motionless WITH RESPECT TO EACH OTHER, I mean, just to head off an evasive "answer."
You're not answering so far, so I will answer for you. If you think my answer is wrong, ask Colton:
You asked: "If you want me to keep answwering these questions, you need to answer this one: If you have two objects X and Y moving at relative speed v to each other, X sees Y moving at v, and Y sees X moving at v. So, how can one be "faster" compared to the other?"
They see it that way because at least one of them is just flat WRONG when he assumes that he is at rest.
SR/GR says one MUST be wrong, because it does not consider motion to be merely apparent and illusory. Both SR and GR assumes the the appearance of motion indicates the presense of actual motion, not illusory motion.
In short, GR/SR does NOT posit, as you have consistently maintained throughout this thread, that "both are correct."
That basic misintepretation has led you to repeatedly make claims that are implicitly, if not explicitly, wildly inconsistent and contradictory throughout this entire thread. Until you correct that misconception, it is impossible to even discuss it with you.
I understand that. I also understood you to say that is IS NOT POSSIBLE for one object to be going faster than another to begin with?
It is possible to say one object is going faster than another after you specify a reference frame, and I havesaid that many times as well. However, regardless of the reference frame you choose, the speed of light in a vacuum will be c, as far as we can tell.
No "measurement" has any meaning whatsoever without a context and some kind of contrast. This would include the concept of "length."
Can you have a length, and a speed, without them being measured? I would think so. Given your past statements, I would be surprised is you did not think so. So, we are not disagreeing about the need or effects of measurement.
That said, I can conceive of length, independent of other objects, and I can conceive of speed, independent of other objects.
What does it mean to have a speed if you are the only object under observation?
This is especially true of acceleration. If I was the only object in the universe but was getting constantly buffeted around because of continuous accelerations and decelerations, I would notice the phenomenon, even if I didn't attribute it to a change in motion.
If yo intterpreted it as acceleration, you would be noticing your change in your current inertial state compared to a former inertial state. That gives you two objects from which you can derive there is a speed involved.
And, in any event, I never said speed took 3 objects to be discerned.
Nor have I. You only need a third object (or frame of reference) to say there is a difference in speed between 2 objects.
One Brow said: "What does "BOTH to [be] simultaneously be at rest" mean, given you defined "at rest" as 'I simply mean that, as between the two of them ... A assumes that he is at rest, and that B is the one "really moving" at the rate of .5c B assumes the opposite. Each assumes that he is "at rest" relative to the other.'?
What does Einstein mean when he says "at rest?"
Einstein is not asking me this question. You are. If I'm going to answer your question, I need to know what it is.
Is your the only answer left in you bag of tricks one which says: I can't understand a word you're saying, even if I can understand the same thing perfectly if anybody else says it?
A: My speed is ZERO, B's is .5c
B: My speed is ZERO, A's is .5c.
Does SR or GR allow for the possibility, that, under these circumstances, A's speed really is ZERO and, at the same time, B's speed really is ZERO?
Yes, or no?
SR/GR does not ever identify A or B has having a speed that is "really ZERO" unitl you specify a reference frame first, and then is it zero only within that reference frame. I've already said that no reference frame has them both with a speed of zero, but that answer did not satisfy you. Further, your expanation of your question is, at best, not bvery consistent with what you said you meant by "at rest". Perhaps these thought are clear in your mind, but in words they are coming out muddled.
Put another way, does SR/GR allow for the possibility that all motion is pure illusion
I think any empirical theory of motion can be transformed into an ontological framework that says all motion is an illusion. However, SR/GR itself treats relative motion as being real motion.
and posit that 2 objects only (falsely) perceive apparent motion between themselves when, it fact, both objects are absolutely motionless?
Again, I have said many times relative motion is real motion, not apparent motion.
They see it that way because at least one of them is just flat WRONG when he assumes that he is at rest.
Within relativity theory, there is no right or wrong to that question, there is only consistency.
SR/GR says one MUST be wrong, because it does not consider motion to be merely apparent and illusory. Both SR and GR assumes the the appearance of motion indicates the presense of actual motion, not illusory motion.
Actually, SR/GR says it doesn't care which, if either, is right or wrong, nor the degree to which they may be right or wrong, because the answers relativity theory derives are always the same whether you say A is at rest, B is at rest, or in any other coordinate system at all, period.
In short, GR/SR does NOT posit, as you have consistently maintained throughout this thread, that "both are correct."
I don't recall ever saying both are correct. Both are equally correct, and equally incorrect, I recall. Since the answers come out the same, it just doesn'[t matter in relativity theory.
That basic misintepretation has led you to repeatedly make claims that are implicitly, if not explicitly, wildly inconsistent and contradictory throughout this entire thread.
I am still hoping to find a way to get this through to you.
Until you correct that misconception, it is impossible to even discuss it with you.
Feel free to stop, then. It would be a shame, after yo have gone through so much, to give up now, though.
One Brow said: "I don't recall ever saying both are correct." Then your memory isn't very good.
One Brow said: "Within relativity theory, there is no right or wrong to that question, there is only consistency."
You'll never get it Eric. The only consistent answer is the one I have given. If both assume they are at rest, then at least one MUST be wrong. This statement is simply wrong: One Brow said: "Both are equally correct, and equally incorrect"
Your only agenda is to scream "THERE IS NO ABSOLUTE MOTION" in every post, whatever the question or particular topic under discussion. Because of that, you cannot discern subject from object, part from whole, hypothetical question from factual question, ontology from epistemology, cannot understand simple language, and just seem unable to make meaningful distinctions in general.
I'm not claiming there is absolute motion, but you feel compelled to "convert" me nonetheless. Your evangelical devotions would be better directed to someone outside the choir.
When I was a chile, my Mama baked-up a big-ass pie. Then she told me and my three brothers "You're all equally entitled to this pie."
Boy, are we glad she said that! We each ate the whole pie.
Your only agenda is to scream "THERE IS NO ABSOLUTE MOTION" in every post,
Within relativity theory, there is not. You haven't been able to define your terms in any concsistent fashion because you are trying to bring in a concept to relativity theory that is foreign to it.
Save your bleating and soapbox-preaching. The truth is that you can't formulated sentences to clearly and consistently convey your ideas, but you refuse to adopt technical terminology that was design to convey these concepts clearly, and then you blame me because I don't adopt your own muddled ways of thinking about the issue. For example, you can't even consistently use the term "at rest", your meaning for it changes from empirical to ontological and back again within paragraphs, defined as subjective to in one viewpoint and then to be analyzed viewpoint-free.
The only consistent answer is the one I have given. If both assume they are at rest, then at least one MUST be wrong.
Of course. Probably both are wrong. The chance of either of them being "really" at rest is infinitesimally small (for any given definiton of "really"), and certainly both are not. So, we agree that one must be wrong. Do you contend that this matters to relativity theory?
Unless, you adopt a completely relative definition of "at rest", such as '... A assumes that he is at rest, and that B is the one "really moving" at the rate of .5c B assumes the opposite. Each assumes that he is "at rest" relative to the other.' Because that definition certainly says, directly,, that A is correct in calling himself at rest and so is B. So, if the person who penned that relative defintion wants to adopt a non-relative definition or "at rest", maybe they should do so?
In relativity theory, none of this matters anyhow. Relative motion is all that is needed to describe the effects seen.
I'm not claiming there is absolute motion, but you feel compelled to "convert" me nonetheless. Your evangelical devotions would be better directed to someone outside the choir.
No? YOu seem to have created this little category of "real motion", which you are sure tells you something more than "relative motion", but is not "absolute motion". How about expanding on that? Do you see a difference between real motion and relative motion? What would it be? Describe it.
One Brow said: "How about expanding on that? Do you see a difference between real motion and relative motion? What would it be? Describe it."
I have done this repeatedly for about 800 posts now. Go back and read them in light of such admissions as this: "The chance of either of them being "really" at rest is infinitesimally small (for any given definiton of "really"), and certainly both are not." You have consistently denied this, going so far as to say that is IMPOSSIBLE for one to be going faster than another in light of the fact that both "see" themselves as being at rest.
One Brow said: "YOu seem to have created this little category of "real motion", which you are sure tells you something more than "relative motion", but is not "absolute motion".
Newsflash: I didn't "create" this "little category. It is a category that has been more or less presupposed by every physicist and philosopher in the history of Western civilization, from Aristotle to Einstein to Hawkings.
You are the one who has acted as though such a notion was incomprehensible and repeatedly implied (on an inconsistent basis) that SR/GR had somehow abolished any notion of "real motion."
One Brow said: "Is this really an argument over more than definition about what it means to have a choice?"
No, you haven't. You have postulated on it, commented on it, criticized me for not getting it, even offered examples of relative motion for it, but you have not once defined what you mean by "real" motion that is more than relative motion but not absolute motion. Frankly, I don't think you can come up with a clear, consistent definition because you don't have a clear, consistent concept, but just a muddle that goes back and forth at need.
Go back and read them in light of such admissions as this: "The chance of either of them being "really" at rest is infinitesimally small (for any given definiton of "really"), and certainly both are not."
What, precisely, do you think those "admissions" indicate that I have not stated directly, multiple times?
You have consistently denied this, going so far as to say that is IMPOSSIBLE for one to be going faster than another in light of the fact that both "see" themselves as being at rest.
For a given definiton of "really at rest", of course it is possible to say which is faster. All you have to do is specify the arbitrarily chosen reference frame (i.e., say what is "really at rest") and most of the time one or the otehr will be faster within that reference frame.
Newsflash: I didn't "create" this "little category. It is a category that has been more or less presupposed by every physicist and philosopher in the history of Western civilization, from Aristotle to Einstein to Hawkings.
Then you should have many sources for a definition at hand. Pick one. Make sure the one you pick is more than relative motion but not absolute motion. Any day now.
You are the one who has acted as though such a notion was incomprehensible
Such a motion as what? I have no "such a" from you to say is incomprehensible.
and repeatedly implied (on an inconsistent basis) that SR/GR had somehow abolished any notion of "real motion."
Abolished? As opposed to ignored, did not reference, did not need? *chuckle*
Of course, since I have been saying for pages that relative motion *is* real motion, your statement is untrue. You seem to feel there is more to real motion than relative motion. I'm still waiting to hear what that something is. Any day now. When you're ready, of course. No rush. I've got all this year and next.
One Brow said: "Abolished? As opposed to ignored, did not reference, did not need? *chuckle*"
Chuckle on, Chucklehead.
When SR predicts, and Einstien himself points out, that the object which is really moving is the one that will really record less time, is real motion being
1. Ignored?
2. Not referenced?
3. Not needed?
4. All of the above and none of the above, depending on who I want to sneer at like a jackass in order to insinuate that it is him, NOT ME, who is an utter ignoramus?
"In his famous work on special relativity in 1905, Albert Einstein predicted that when two clocks were brought together and synchronized, and then one was moved away and brought back, the clock which had undergone the traveling would be found to be lagging behind the clock which had stayed put."
I doubt you have any clue what all this could possibly be saying, Eric, because I don't see any "techncial" terms in there. Hmmmm, maybe Al's own words would help, eh?:
"If we placed a living organism in a box ... one could arrange that the organism, after any arbitrary lengthy flight, could be returned to its original spot in a scarcely altered condition, while corresponding organisms which had remained in their original positions had already long since given way to new generations. For the moving organism the lengthy time of the journey was a mere instant, provided the motion took place with approximately the speed of light."
http://en.wikipedia.org/wiki/Twin_paradox
My bad, no technical terms there, either. Maybe your 7 year old daughter can translate it for you, eh?
One Brow said: "Such a motion as what? I have no "such a" from you to say is incomprehensible."
There are none so blind at those who will not see, eh, Eric? That Einstien is such a FOOL! What could he POSSIBLY mean by these meaningless and incomprehenisble phrases?
"its original spot"
"remained in their original positions"
"the moving organism"
"time of the journey"
"Remained!?" Get real, eh? "Moving!?" What in the hell is that supposed to mean, I ax ya? "Original spot?" "Journey?" How stupid can ya git?
I had a homey ax me once if I would teach his 15 year old boy some algebra. I said I would try. Turns out, this youngun was a watermelonhead. A mongoloid idiot, ya know?
After a few weeks I told his Pappy: I don't think your boy is gunna understand.
His Pappy got all kinda pissed off. He says: "He can understand, aint, you just can't tell him in a way that is understandable. Just like you to blame a poor boy for your own serious shortcomings. I aint payin!"
Chuckle on, Chucklehead.
As long as you keep bringing the funny, sure thing.
When SR predicts, and Einstien himself points out, that the object which is really moving
Einstein never says words that translate as "really moving", and mean something other than "relatively moving", within the confirnes of relativity theory. Since you won't define what you mean by really moving, I have no idea what you think Einstein is talking about. But it's really just plain old relative motion.
"In his famous work on special relativity in 1905, Albert Einstein predicted that when two clocks were brought together and synchronized, and then one was moved away and brought back, the clock which had undergone the traveling would be found to be lagging behind the clock which had stayed put."
I doubt you have any clue what all this could possibly be saying, Eric, because I don't see any "techncial" terms in there.
Seems fairly clear. The one that is being moved away is being placed in a non-inertial reference frame, which means it begins to experience less time.
Hmmmm, maybe Al's own words would help, eh?:
Maybe if you had all of Einstein's words, so you could see the context refers to the organism on the lengthy flight changing inertial reference frames, that would help you. Or, if you had the original quote, and it said something along the lines of "that organism in the rocket is really moving, and that't why this happens", that would help me.
Instead, you have repeated the same stuff without bringing in any evidence at all that the concept of "really moving" is used by relativity to get the answer. You still can't even define what you mean by "really moving", which is supposed to be more than rlatively moving, or bring in a single reference that makes this distinction. You still have not responded to the Pat/Chris mathematics, where even after I granted your assumption Pat has accelerated in the past, that had no effect on the future results.
So, while I thank you for the offer to have your 7-year-old translate it, how about you undertake some effort to justify your claims instead of repeating them? Let's start with an easy one: describe the difference between relative and real motion.
What could he POSSIBLY mean by these meaningless and incomprehenisble phrases?
Without the whole quote, who knows?
Wait, *you* know, right? Go ahead, explain it. What does Einstein say is the difference between real and relative motion, according to you? Any time now. No rush. I'll be around.
With respect to the "technical terms" which only YOU understand, and which wiki and other experts obviously don't understand.
Newton said that, if he were not rotating, a person sitting on earth could be considered to be in an "inertial" state. Einstein later said: No, Newton was wrong. Such a person would be in an accelerated state, not an inertial one.
Why? Because of his equivalency principle. He said that a person in outer space, being UNIFORMLY ACCELERATED (the caps are there for emphasis, because this is important) with a force of 1g would be in an "equivalent" position as the one sitting on earth.
So how about a person in "free fall?" They are "weightless." Why? Because they are NOT being accelerated, they are in UNIFORM UNACCELERATED (as opposed to UNIFORMLY ACCELERATED) motion, under the effect of gravity (or curved space, if you prefer).
So, Al said, anyone who is "free fall" is the one who is "inertial," but the term "free fall," in that sense, cannot be applied to any object that in not in uniform motion, i.e. not moving at a steady rate of speed (has not reached terminal velocity, if ya want).
Being "accelerated in free fall" is basically a contradiction in terms, under GR, if you read free fall to mean "inertial." Newton would have said that one in free fall was accelerated, because it was constantly changing "direction" (from that of a euclidean straight line) even if it was going at a uniform "rate of speed." Einstien chooses to call this uniform (weightless) motion intertial, and hence, unaccelerated by definition. In GR the "equivalence" between gravity and acceleration only equates a person on earth with a person being accelerated with a force of 1g. Both are accelerated states, not inertial states, as Newton claimed, according to Al. In Einstien's example, the one clock can be said to be in "free fall" only insofar as that terms merely means acting under the force of gravity alone. But an accelerated free fall is NOT an inertial state. Therefore the clock in "free fall" is not inertial in that case.
So much for "inertial."
With respect to SR and the absence of "straight lines" within the SR framework, let me quote Einstein directly on the topic:
"a Galilean coordinate system in the sense of the special theory of relativity [is] a frame of reference, relative to which isolated, material points move in straight lines and uniformly."
His "resolution" of the twin paradox basically consisted of the standard one---SR don't deal with accelerated frames of reference:
"Indeed this theory [SR] asserts only the equivalence of all Galilean (unaccelerated) coordinate systems, that is, coordinate systems relative to which sufficiently isolated, material points move in straight lines and uniformly. K is such a coordinate system, but not the system K', that is accelerated from time to time."
http://en.wikisource.org/wiki/Dialog_about_objections_against_the_theory_of_relativity
Here he personally equates inertial status with "unaccelerated" frames, in the context of SR.
My point? Your insistence on such claims as "SR does not deal with motion in a straight line" and your confusion of a uniformly accelerated object as one in "non-detectable free fall" are just wrong. You are not the ONLY one who can define these concepts, as you like. Acceleration can be detected by a person subjected to it. GR does not change this.
Such considerations provide all the more reason not to try to engage you in a discussion which imports your conceptions of the meaning of "technical" terms, and then spend a lot of time clarifying the true meaning of such terms as "inertial" (which happens to be very problematic to begin with in both SR and GR).
If you feel you have been "cheated" out of chance to create even more confusion because I refused to accept your assertion that the basic concepts could ONLY be discussed under such circumstances, I'm sorry. But to suggest that such terminology is needed to discuss simple, everyday ideas, is just absurd. Call a state "inertial," or call it "unaccelerated," I don't care, but I don't want to quibble about it all year.
Since you finally admitted that relativity does not abolish the notion of real motion, I would have hoped that the false "distinction" you made before would have gone away.
There is no difference, per se. Relative motion is real. Real motion is relative. Get it? The term "relative" does not mysteriously and magically change the character of "motion," as you have been implying. Jesus, you make a bogus distinction, which I deny exists, and then you say I must clear up your mental errors to your satisfaction. You have admitted your mistake (kinda, anyway, you still try to deny it). There is nothing to clear up, except your mind.
In the twin paradox, the earthtwin says: I have the theoretical and hypothetical right to claim that *I* am the one really moving.
Relativists' answer: Yeah, ya do. You also have the right to be wrong, and you ARE wrong. You were not the once moving, the spacetwin was and that is why the spacetwin is younger than you are.
"Hypothetical" motion is not "real motion."
Let me bring in a "third frame" for you.
I am 50' away from a solid concrete wall, about 100 feet wide. Behind me, about a mile away is a car. We both approach the wall, me at a walking speed, the car at a god-awful high speed. You could say the wall is approaching us, and even that we are both simultaneously moving away from it at different rates of speed, I spoze, but either way, the car is gaining on me.
We reach the wall at the same time. I put my hand out and touch it, the car smashes into it and the driver is killed. Who was really moving here? Who was going faster?
Well, let's just haul off and assume, in a wildly arbitrary and caprious fashion, that the wall was motionless. The car was moving faster than me, even if the wall was approaching us, because the wall was "closing distance" on the car at a much higher rate of speed, so the wall is really irrelevant.
Now, take away the wall. Would that suddenly change who was going faster?
Anytime two things are moving with respect to each other, it is virtually guaranteed that one is moving faster than the other, except in those coincidental cases where the individual contribution of each object to the total rate of separation (or approach)is exactly equal.
The fact that, in theory, I can claim that either one of two objects is moving does not, and can not, change their "real world" state of motion, whatever it may be.
A few excerpts, from about 500-600 posts ago:
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.
====
A second time you said: "Pat sees Chris as being younger, Chris sees Pat as being younger, both are correct.
===
After you proclaimed that the answers given in the wiki articles were "correct," I said:
"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."
In reply, you said: "At no time is one "right" and the other "wrong"...The wiki pages do not identify either Bob or Rob as being "correct" or "wrong" at any time.
====
Of course then you throw in such doozies as: "even if you assume Rob is moving and Bob is stationary, the answer is still that Bob will be younger," which is totally contrary to what both wiki and Einstien himself said about the time-dilating effects of speed.
And you want to act like I'm confused?
You have simply been totally unable to distinguish "hypothetically imputed motion as I arbitrarily see fit, from time to time" from actual motion.
Two objects, A and B, are moving relative to each other out in space (let A be a voyager spacecraft we launched years ago, and B the the planet neptune). Because YOU, sitting at your computer, can hypothesize an observer sitting on the planet neptune, and because you say that observer can consider himself to be in motion relative to the spacecraft, then the spacecraft "can" be motionless, and it would therefore be "incorrect" to say that the spacecraft is actually moving in relation to the planet.
As if your arbitrary postulations can actually affect the motion of either the spacecraft or the planet, eh?
The one who is "really moving," as I have said God only knows how many times, is the one who is actually moving; moving in reality; the one who has actual, as opposed to merely hypothetical or theoretically possible, motion; one whose motion is not merely illusory."
I mean "moving" in precisely the way Einstein meant it in his example, which is the way all people use it, as a rule. Some people don't. Some people say things like "motion is inherently relative" and think they have said something meaningful and profound. They think that "relative motion" is something unique and distinct from real, actual motion. They then claim they cannot even begin to comprehend what actual motion could possibly mean. All motion is relative, not actual!
One Brow said: "...six month ago Pat was accelerated to .6c compared to Chris.Let's say pat and Chris are both exactly 12,000 days old, as they have each experience time, when they are close to each other."
Best I can tell here, all you are saying by throwing in the phrase "as they have each experience[d] time" is to say:
Let's assume both see themselves as at rest, and so let's assume that both were, in fact, simultaneously at rest, the whole time that Pat was approaching Chris at the rate of .6c, with all true and actual motion being imputed to Pat.
What does "12,000 days old," as they have each experience time," mean?
It seems to me that it is saying, even though I just expressly stipulated that Pat was moving toward Chris at the rate of .6c, I am going to treat his age as though he in fact remained stationary. I am going to ignore my own express stipulation, and assume that during this 6 month period, BOTH Pat and Chris were IN FACT at rest.
According to SR, one could NOT approach the other at a rate of .6c for a period of six months with the result that, after that 6 months, they would both, in fact be, the same age.
There is no "math" in this problem whatsover, only the repetition of your ongoing inability to refrain from your erroneous assumption that, if each one assumes he is at rest, then each one must, in fact, actually BE at rest.
This whole Pat and Chris thing is not the least bit complicated.
1. P & C pass each other at the relative speed of .6c and neither accelerates or decelerates for the next 20 years.
2. P sees himself as at rest,
3. C sees himself as at rest.
Assume P is right. Relative to C, at least, he is in fact at rest. C is therefore WRONG.
C WILL BE younger, even if he thinks P is younger, and even if they never meet again.
End of story.
====
Assume C is right. Relative to P, at least, he is in fact at rest. P is therefore WRONG.
P WILL BE younger, even if he thinks C is younger, and even if they never meet again.
End of story.
You have been denying this for about 700 posts now.
In neither case are P and C "both correct" or "equally correct" in their mutually exclusive assumptions. Get it?
And all that is a simple matter of SR/GR theory. Those theories do NOT say "both are correct." On the contrary, both theories say "both CANNOT be correct, one MUST be incorrect."
With respect to the "technical terms" which only YOU understand, and which wiki and other experts obviously don't understand.
You seem to think that I hold my opinion as being different from the wikis in some fashion. You are incorrect. I have been tryin to explain what the pages have been saying. You have been so eager to point out my errors that it takes dozens of posts to even get you to acknowledge the most basic interpretational error. So, while I could say a lot more to your responses, I believe we have been going in circles enough.
I think it time to invoke a other parties. If you approve of them (we should at least be able to agree on what the questions say), I'll pass them on to colton, and you can pass them on to some physics expert of your choice also.
1. In the twin paradox listed in and http://en.wikipedia.org/wiki/Twin_paradox, does the answer to which twin is younger depend in any way on the notion of which twin is "really moving?
2. In Einstein's dialog http://en.wikisource.org/wiki/Dialog_about_objections_against_the_theory_of_relativity, in coordinate system K', is U1 always in an inertial environment?
3. Is there ever a case where acceleration by free fall is not an inertial environment?
4. Pat and Chris are born on widely separated planets in approximately the same rest frame, and Pat is then accelerated to .6c in the general direction of Chris. When Pat passes Chris, both are exactly 12,000 days old. As long as neither accelerates, will you be able to say that Pat will be younger than Chris from then on?
My understanding is that you would answer these questions as 1. yes, 2. no, 3. yes, 4. yes. My answers are 1. no, 2. yes, 3. no, 4. no. Let me know if you want to add anything else.
I have told you repeatedly that I don't want to quibble over the meaning of a word, especially when the meaning of a particular word is NOT EVEN RELEVANT to the issue at hand. As far as the Einstein example goes, the issue was whether the frames K and K' were mirror images.
My specific question was: "Are you seriously trying to say that the "planetary" clock (clock U2)is in an inertial (unaccelerated) state in both frames?"
Do you see where I have "unaccelerated" in parentheses to indicate what I mean by "inertial?" That is precisely the way I have quoted both wiki and Einstein himself as using the term, i.e., inertial = unaccelerated.
Strike the word "inertial," I don't care to argue about it. The question is:
Are you seriously trying to say that the "planetary" clock (clock U2)is in an unaccelerated state in both frames?"
The question is NOT "what does inertial mean, and to whom?" The question is about the lack of symmetry and consistently in the two frames. Do you answer the question the same way if I simply say "unaccelerated," and leave the synonym, "intertial" out of it?
1. In the twin paradox listed in and http://en.wikipedia.org/wiki/Twin_paradox, does the answer to which twin is younger depend in any way on the notion of which twin is "really moving?
So long as it is understood that "the answer" does NOT include the bogus "GR" (non) solution. Time dilation due to an increase relative speed is kinematic, and that's the only issue here. Not bogus offsetting time contraction due to gravitation. Leave gravitation out if it. It is an SR question, from beginning to end.
Rephrase the question:
4. Pat and Chris are born on widely separated planets in the same rest frame, and Pat is then accelerated to .6c in the general direction of Chris. At the time Pat accelerated, he and Chris are the same age, according to their identical respective time frames. As long as neither accelerates, will you be able to say that Pat will be younger than Chris from then on?
Leave out the word "approximate"
Omit this irrelevant and assumption-laden claim: "When Pat passes Chris, both are exactly 12,000 days old."
I have made quite a few posts here which you have ignored. Is there any other issue of substance where you have disagreement, or is that it? In particular, do you in any way dispute the 3 posts I made immediately before you made yours?
In the above post about accelerated (inertial) motion in Einstien's example, that was not the question I had in mind. The question (and answer) I was intending to refer to was this:
I asked you if you agreed that:
1. In frame K, clock U1 is inertial AT ALL TIMES?
2. In frame K', neither clock is inertial AT ALL TIMES?
Your answer was: "In both frames K and K', clock U1 is inertial at all times."
I'm not sure how to rewrite Q1 to address your concerns, but I gave it a try. I was not planning an editoroizling, just asking the quesitons directly. Did you have any changes to add?
As for 4., maybe I'll present your version as #5. I don't think you can say two people born many light-years apart can ever be said to be born "at the same time" in relativity theory.
So, let's try this set:
1. In the twin paradox listed in and http://en.wikipedia.org/wiki/Twin_paradox, does the answer to which twin is younger depend in any way on the notion of which twin is "really moving", as opposed to looking at relative motion only?
2. In Einstein's dialog http://en.wikisource.org/wiki/Dialog_about_objections_against_the_theory_of_relativity, in coordinate system K', does U1 experience acceleration?
3. Is there ever a case where acceleration by free fall is not an inertial environment?
4. Pat and Chris are born on widely separated planets in approximately the same rest frame, and Pat is then accelerated to .6c in the general direction of Chris. When Pat passes Chris, both are exactly 12,000 days old. As long as neither accelerates, will you be able to say that Pat will be younger than Chris from then on?
5. Tom and Ron are born on widely separated planets in the same rest frame, and Tom is then accelerated to .6c in the general direction of Ron. At the time Tom accelerated, he and Ron are the same age, according to their identical respective time frames. As long as neither accelerates, will you be able to say that Pat will be younger than Chris from then on?
Would your answer be the same if I substituted "accelerated" where I used "inertial?"
I have made quite a few posts here which you have ignored. Is there any other issue of substance where you have disagreement, or is that it? In particular, do you in any way dispute the 3 posts I made immediately before you made yours?
Yes, I have substantial disagreements with those posts. However, I see those issues as being secondary to (that is, dervied from) other, more fundamental issues. If you like though, we can add a basic question 6.:
6. Within relativity theory, can there be there such a thing as a wrong viewpoint to take?
Since we agreed U1 was inertial (did not experience acceleration) in K, I didn't think it was necessary to ask that. I can add it, if you like.
Would your answer be the same if I substituted "accelerated" where I used "inertial?"
Assuming you are referring to U1, my answer would be that this is view-point dependent. U1 never experiences acceleration, but U2 seems U1 as accelerating.
One Brow said: " does the answer to which twin is younger depend in any way on the notion of which twin is "really moving", as opposed to looking at relative motion only?
I thought we just we through this. The question, all confusions aside, is simply which one is "moving," with the only (unnecessary, except for those who THINK there is a difference) understanding being that "moving" means real, actual motion, not hypothetical, theoretical, or imaginary motion. It is "real" motion, not that which might be falsely assumed by some uninformed party.
Are YOU now claiming that there is some opposition between motion and "relative motion only?"
Are YOU now claiming that there is some opposition between motion and "relative motion only?"
As I have consistently maintained, there is *no* difference between real and relative motion, at least within relativity theory. The solution to the twin paradox is based on relative motion only, because all real motion is relative motion.
One Brow said: "Yes, I have substantial disagreements with those posts...If you like though, we can add a basic question 6."
If you want to relay those 3 posts, verbatim to Colton (or just refer him to this website to read them for himself), then I would be interested in knowing if he disagrees, and if so, about what and for what reasons.
I will not rely on his response to some restatement of the issue which you try to concoct.
What are YOUR "substantial disagreements?"
I will not rely on his response to some restatement of the issue which you try to concoct.
Concoct your own, then.
What are YOUR "substantial disagreements?"
Re-reading them, I don't have one after all. You seem to have acknowledged that there is no reason to prefer Pat's viewpoint over Chris', nor to prefer Chris' over Pat's, which I have been trying to get across to you for the last 700 comments. I see no sign of you trying to claim that one of them has a preferred viewpoint. I'm good with that.
Sorry, spoke too soon:
And all that is a simple matter of SR/GR theory. Those theories do NOT say "both are correct." On the contrary, both theories say "both CANNOT be correct, one MUST be incorrect."
Actually, relativity theory says any issue issue of which one is correct or incorrect is moot. Neither viewpoint can be correct or incorrect in relativity theory.
One Brow said: "Assuming you are referring to U1, my answer would be that this is view-point dependent. U1 never experiences acceleration, but U2 seems U1 as accelerating."
Einstein tells you what is really happening. He does not say: "Just ignore everything I've said in this illustration because nothing I said can be counted on...It's all simply "view-point dependent" and any presentation about the true nature of what is happening, as I have given it, is not reliable at all. You are entitled to say I am wrong if you simply wish to take another view-point. I am neither right or wrong....there is, and can be, no right or wrong....it's all simply OBSERVER DEPENDENT."
One Brow said: "Concoct your own, then."
I am not asking a question. I am making claims. If Colton cares to read them, he can tell me if he agrees or disagrees.
One Brow said: "Neither viewpoint can be correct or incorrect in relativity theory."
First it was that both are correct, now neither. THIS is what I want to ask Colton, because THIS is the one misconception that you continute to labor under and which makes discussion virtually impossible.
When Einstien gave his statement of the "living organism" who travelled, was everything he said neither correct nor incorrect?
One Brow said: "As I have consistently maintained, there is *no* difference between real and relative motion, at least within relativity theory. The solution to the twin paradox is based on relative motion only, because all real motion is relative motion."
Then why would you phrase the question the way you did. Colton won't even know what you're talking about, just as I don't (I think I do know what you must be thinking, but it is not coherent).
"One Brow said: " does the answer to which twin is younger depend in any way on the notion of which twin is "really moving", as opposed to looking at relative motion only?
"Einstein tells you what is really happening."
Relativity doesn't care what is "really happening". It is irrelevant. All view points are correct. All view points are equally correct. All viewpoints are equally incorrect. You get the same answer regardless of viewpoint. Relativity operates with relative motion only.
It's all simply "view-point dependent" and any presentation about the true nature of what is happening, as I have given it, is not reliable at all.
It is only sheer stubbornness, or a complete lack of understanding, on your part that you think the first clause is in any way related to the second.
Colton won't even know what you're talking about, just as I don't (I think I do know what you must be thinking, but it is not coherent).
Then Colton can so tell me. You keep insisting there is some difference, because knowing which one is really moving is supposedly the key to figuring out which is younger. If there is no difference, that supports my point of view.
So...
1. In the twin paradox listed in and http://en.wikipedia.org/wiki/Twin_paradox, does the answer to which twin is younger depend in any way on the notion of which twin is "really moving", as opposed to looking at relative motion only?
2. In Einstein's dialog http://en.wikisource.org/wiki/Dialog_about_objections_against_the_theory_of_relativity, in coordinate system K', does U1 experience acceleration?
3. Is there ever a case where acceleration by free fall is not an inertial environment?
4. Pat and Chris are born on widely separated planets in approximately the same rest frame, and Pat is then accelerated to .6c in the general direction of Chris. When Pat passes Chris, both are exactly 12,000 days old. As long as neither accelerates, will you be able to say that Pat will be younger than Chris from then on?
5. Tom and Ron are born on widely separated planets in the same rest frame, and Tom is then accelerated to .6c in the general direction of Ron. At the time Tom accelerated, he and Ron are the same age, according to their identical respective time frames. As long as neither accelerates, will you be able to say that Pat will be younger than Chris from then on?
6. Within relativity theory, can there be there such a thing as a wrong viewpoint to take?
My statement: And all that is a simple matter of SR/GR theory. Those theories do NOT say "both are correct." On the contrary, both theories say "both CANNOT be correct, one MUST be incorrect."
Your contention: "Actually, relativity theory says any issue issue of which one is correct or incorrect is moot. Neither viewpoint can be correct or incorrect in relativity theory."
I take it that you are not even aware that you gave the opposite answer a few posts back. You say one thing in one post, and then the opposite in the next. It makes it impossible to know what you are saying, let alone thinking.
Then Colton can so tell me. You keep insisting there is some difference, because knowing which one is really moving is supposedly the key to figuring out which is younger. If there is no difference, that supports my point of view.
Can you (do you) even read? That is NOT my position, as I just said a few posts up. Relative motion is real motion (you have frequently implied that it is not). Real motion is relative.
One Brow said: Relativity doesn't care what is "really happening". It is irrelevant. All view points are correct. All view points are equally correct. All viewpoints are equally incorrect. You get the same answer regardless of viewpoint. Relativity operates with relative motion only.
This is wrong. Profoundly and amazingly wrong. And you still can't see it, despite your explicit disagreement.
As a "theory" SR cares about nothing, that's true. However, unlike yourself, Einstein, and every other theorists of any repute, DOES care if SR is self-contradictory. Your statement is a glaring inconsistency, and you just admitted as much, but you have forgotten already. Relativity doesn't care what is really happening, but "it" does care if it can be applied to reality in a meaningful way. SR does NOT, repeat NOT, posit that all motion is illusory.
However, unlike yourself, Einstein, and every other theorists of any repute, DOES care if SR is self-contradictory.
I haven't said anything that makes it self-contradictory. Saying all viewpoints come out the same is the height of self-consistency.
SR does NOT, repeat NOT, posit that all motion is illusory.
Nor did I say it does.
Your last two comments contradict each other, seemingly.
Which is true, according to you right now:
You always get the right answer in the twin paradox simply by looking at the relative motion, or you need to look at something beside relative motion to get the correct answer.
One Brow said: "U1 never experiences acceleration"
I have asked you this before, and you never responded, other than to assert that you were right and I wasn't. Why does Einstien himself say: "Clock U1 is accelerated...Clock U1 is accelerated in the direction of the positive x-axis until it has reached the velocity v?"
One Brow said: "I haven't said anything that makes it self-contradictory. Saying all viewpoints come out the same is the height of self-consistency."
You never contradict yourself, in your mind, because you are incapable of seeing your own self- contradiction. You denied that this was true:
"In neither case are P and C "both correct" or "equally correct" in their mutually exclusive assumptions. Get it?...And all that is a simple matter of SR/GR theory. Those theories do NOT say "both are correct." On the contrary, both theories say "both CANNOT be correct, one MUST be incorrect."
One Brow asked: "You always get the right answer in the twin paradox simply by looking at the relative motion, or you need to look at something beside relative motion to get the correct answer."
I take this to be a question. The answer is that relative motion is all that's required. But I think I have a different conception of relative motion than you do.
For me, relative motion is real motion. It is not illusory, imaginary motion. It is not hypothetical motion that a party may falsely impute to himself or others. For you the opposite seems true.
To me the adjective "relative" neither adds or subtracts anything whatsoever from motion itself. As I have before:
1. The statement "Bob and Tom are in motion relative to each other," can be seen as making a less specific claim than
2. "Bob is outrunning Tom," or "Bob is leaving, Tom is staying," but the motion is the same either way.
Most would probably say that statement 1 above is merely making a relative claim while both statements in two are making absolute claims. But since I know you have a knee-jerk reaction to, and a limited conception of he meaning of, "absolute" in the context of relativity, I have tried to avoid using it in that common sense.
One Brow said: Relativity doesn't care what is "really happening".
As I said, I agree. Relativity, qua theory, cares nothing about what is really happening. The following statement is NOT part of relativity theory:
"All frameworks are equally valid"
That is an independent, onotological add-on that many, as a personal philsophy like to bring to relativity.
But even then, the foregoing philosophical claim does not entail this claim:
"Therefore, it is quite permissible to say that two mutually exclusive frameworks are equally valid at the same time." This is the self-contradictory extreme to which you carry it, however.
I have asked you this before, and you never responded, other than to assert that you were right and I wasn't. Why does Einstien himself say: "Clock U1 is accelerated...Clock U1 is accelerated in the direction of the positive x-axis until it has reached the velocity v?"
Sorry, that is a good question and I should have answered it. In coordinate system K', U1 changes it velocity. So, in that regard, U1 is accelerated. However, U1 does not experience acceleration. By this, I mean if a person in the same frame as U1 conducts an experiment designed to detect acceleration, such as releasing a ball and seeing if it floats or drops, U1 never detects acceleration. This is true regardless of whether the coordinate system is K or K'.
"In neither case are P and C "both correct" or "equally correct" in their mutually exclusive assumptions. Get it?...And all that is a simple matter of SR/GR theory. Those theories do NOT say "both are correct." On the contrary, both theories say "both CANNOT be correct, one MUST be incorrect."
I did not contradict the part before the ellipses, only the part after the ellipses. The former did not reference relativity theory, the second did.
The following statement is NOT part of relativity theory:
"All frameworks are equally valid"
That is an independent, onotological add-on that many, as a personal philsophy like to bring to relativity.
The quoted sentence is epistemological, and more specifically empirical, not ontological, and is actual foundational to relativity theory.
For me, relative motion is real motion. It is not illusory, imaginary motion. It is not hypothetical motion that a party may falsely impute to himself or others. For you the opposite seems true.
I have not once referred to any sort of illusary motion. Whether you adopt coordinate system K (and see U2 as being subject to propulsion) or K' (and see U1 moving in freefall), the relative, real motion of the clocks is the same.
Applying the "Bob and Tom" statments to the clocks U1 adn U2, which do you think is correct:
Statement one is all you need to correctly identify the clock that has moved less
or
You need something like statement 2 to say which clock moved less.
(Hint: the correct answer is statement 1).
I said: "For me, relative motion is real motion. It is not illusory, imaginary motion. It is not hypothetical motion that a party may falsely impute to himself or others."
In the specific wiki example, given the premises...
1. The earth twin, who considers himself to be stationary with respect to the spacetwin and, correspondingly, considers the spacetwin to be moving away from him, toward a distant star is correct. He is correctly perceiving the true, actual, real (relative) motion between the two.
2. Conversely, to the extent, if any, that the spacetwin considers himself to be at rest, with the implicit understanding that motion between them is explained by the "fact" that the earth is moving away from him, he is INCORRECT. His assessment of the (relative) motion is illusory, imaginary, and falsely imputed to the earth, rather than himself.
Any notion that "both are correct" is absurdly self-contradictory.
One Brow said: So, in that regard, U1 is accelerated.
Ok, fine, we agree after all, at least to this part.
You go on to say: "However, U1 does not experience acceleration. By this, I mean if a person in the same frame as U1 conducts an experiment designed to detect acceleration, such as releasing a ball and seeing if it floats or drops, U1 never detects acceleration. This is true regardless of whether the coordinate system is K or K'."
I disagree with this. Suppose the "clock U1" in K'
was a person. He would feel the acceleration, until he acheived terminal velocity (ceased accelerating). This is why I CAPITALIZED the distinction between acceleration at a uniform rate (equivalent to a newtonian gravitational field, and therefore a non-inertial state per Einstien) and uniform motion in free fall in my prior post. If a guy in a spaceship, in free fall, suddenly accelerated at a uniform rate equal to 1g, he would know it because he would suddenly "gain weight." He would no longer be able to let go of his wine glass and have it "float" beside him. It would "hit the floor" now.
You seem to be under the impression that the earth twin and space twin see different relative motions. They do not. They see the exact same relative motion. Since they see the same relative motion, it is not possible for one of them to be correct and the other incorrect.
Relative motion has no rerference frame built into it. When you discuss coordinate system K, you are looking at one reference frame, and with K' you are looking at a different reference frame. Both reference frames are describing the same relative motion.
I disagree with this. Suppose the "clock U1" in K' was a person. He would feel the acceleration, until he acheived terminal velocity (ceased accelerating).
If you really think this, you still don't understand K'. It is not possible for U1 to experience no acceleration in K and to experience acceleration in K', because K and K' describe the same real, relative motion. The same events are occuring, so the experience is the same.
If you are accelerating in freefall according to some reference frame, the wine glass does not go anywhere. That's what freefall is.
In neither case are P and C "both correct" or "equally correct" in their mutually exclusive assumptions. Get it?...And all that is a simple matter of SR/GR theory. Those theories do NOT say "both are correct." On the contrary, both theories say "both CANNOT be correct, one MUST be incorrect."
I did not contradict the part before the ellipses, only the part after the ellipses. The former did not reference relativity theory, the second did.
Either way, the contradiction is the same. SR/GR does not countenance the notion that motion is merely illusory, so it emphatically ratifies the part BEFORE the ellipse. You claim it denies the part before the ellipse and, implicitly, that it therefore endorses the notion that motion is merely illusory.
Either way, the contradiction is the same. SR/GR does not countenance the notion that motion is merely illusory, so it emphatically ratifies the part BEFORE the ellipse. You claim it denies the part before the ellipse and, implicitly, that it therefore endorses the notion that motion is merely illusory.
"Denies"? No. Ignores, because it is not relevant to relativity. All that matters are the relative descriptions of motion. All descriptions of the same relative motion give teh same result in relativity theory. Relativity theory is not capable of ratifying the sentence before the ellipse.
One Brow said: The quoted sentence is epistemological, and more specifically empirical, not ontological, and is actual foundational to relativity theory."
I know what you are saying here, and partially agree. As a strictly empirical/epistemological matter, SR does assume that absolute motion is undetectable (or, at a minimum, does not consider it to be a "necessary" element of the theory).
On the other hand, the actual statement I made was this:
"All frameworks are equally valid"
It is one thing to say that "no one preferred frame of reference can be detected," and quite another to claim that all frames are equally valid.
The "equally valid" assumption is strictly a philosophical/ontological premise. It has a theoretical, but not a practical, foundation. As a practical matter, we routinely assume that the earth orbits the sun, not vice versa, for example. And we do not make this assumption "arbitrarily;" we make it for a host of empirical reasons. Theoretically and philosophically speaking, we are not compelled to make this asssumption, but, again, that is primarily a theoretical/philosophical distinction.
One Brow said: "I have not once referred to any sort of illusary motion. Whether you adopt coordinate system K (and see U2 as being subject to propulsion) or K' (and see U1 moving in freefall), the relative, real motion of the clocks is the same."
No, of course you don't refer to illusory motion by name. But you do it implicitly when you say BOTH frames, with their mutually exclusive causes and explanations, are correct. It's either one or the other (or even perhaps neither) as a matter of "reality."
It's one thing to say "In a given situation, I will be unable to detect whether I am being unformly accelerated or simply in a gravitational field," and it is quite another to implicitly assume that it can therefore be both, at the same time. In truth, it is either one or the other, whether you can detect the "truth" or not. This is what you consistently try to disavow (i.e., that it is even possible for there to by any "truth" about the matter).
One Brow asked: "Applying the "Bob and Tom" statments to the clocks U1 adn U2, which do you think is correct:"
I'm sorry, but I must not understand understand the question.
You say: "Statement one is all you need to correctly identify the clock that has moved less...(Hint: the correct answer is statement 1).
I don't think statement 1 is sufficient to tell you which clock has moved less, and I can't conceive of any reason why you would think it is, especially in light of your other statements in this thread.
One Brow said: "You seem to be under the impression that the earth twin and space twin see different relative motions. They do not.
WHAT!? What have I ever said that would make it seem like I think they are seeing different motion?
"Since they see the same relative motion, it is not possible for one of them to be correct and the other incorrect."Again, WHAT!? Are you saying that it is IMPOSSIBLE for either of them to make incorrect assumptions about which one is moving?
"Relative motion has no rerference frame built into it."
What is this even supposed to mean? I am talking about two twins observing each other separate from each other at a constant rate of speed.
"When you discuss coordinate system K, you are looking at one reference frame, and with K' you are looking at a different reference frame. Both reference frames are describing the same relative motion."
This sounds better suited for the Math Geek message board. What is the significance of this statement? I think I understand it, but I also think it's inherently obvious and have no idea why you think it is necessary or pertinent to state it at this time.
One Brow said: "If you really think this, you still don't understand K'. It is not possible for U1 to experience no acceleration in K and to experience acceleration in K', because K and K' describe the same real, relative motion. The same events are occuring, so the experience is the same."
WRONG on virtually every conceivable matter. Are you now claiming that clock U1 is accelerated in frame K, too!? They are not the "same events" by any stretch of the imagination. The "because" you throw in just assumes your mistaken conclusion. Here again, I suspect you are merely reasoning backwards. Einstien wanted to present a scenario that gave the appearance of being "the same," therefore it MUST be the same.
In frame k, U1 is truly inertial--it is being acted upon by no external forces whatsover, gravity included. In k', as Einstien specifically admits, it is being accelerated by an extremely powerful gravitational field. It is accelerated, not inertial. That acceleration is detectable, in principle, but, that too is ultimately irrelevant. Ability to detect does not equal ability to be true.
I really can't believe you fall for this crap.
One Brow said: "If you are accelerating in freefall according to some reference frame, the wine glass does not go anywhere. That's what freefall is."
Wrong again. I have already quoted wiki on this matter. In it's broadest sense, "free fall" means "acting under the influence of gravity alone." Most people don't use it in that broad sense. They use it to mean "moving UNIFORMLY under the influence of gravity alone." You are thinking of the second, colloquial sense of the word.
But in the broad sense, there are two distinct brands of "free fall"
1. Accelerated free fall, and
2. Unaccelerated free fall.
In case one, you will feel "g forces." In case two, you will not, and you will be weightless.
Einstein's example is case 1, accelerated free fall, which he himself admits.
Anyone who has ever done a "stall" in an airplane, or taken a ride on a roller coaster, knows the difference between accelerated and unaccelerated free fall.
A skydiver feels acceleration when he jumps out of a plane, and contintues to feel it until he reaches terminal velocity, at which time it is virtually the equivalent of being in orbit--i.e., he feels "nothing" as a result of his motion (because it is no longer accelerated motion).
One Brow said: "Relativity theory is not capable of ratifying the sentence before the ellipse."
Of course it is. Why would you even think it wouldn't be? Ask Colton to read those 3 posts and offer his input, if you wish.
I wish you would ask him. THIS is the PRIMARY source of all the self-contradictory claims you make.
Einstein liked to tell the tale of the time his neighbor fell off his roof. Al asked him what it felt like. The neighbor said it didn't feel like anything until he hit the ground. Al took this to heart, apparently, not realizing that his neighbor was rather unobservant.
I remember that there one time, when I wuzza chile, when my Mama gimme a serious ass-whuppin. She cooked up a chicken for me and my sister, then cut it in half. She said "aint, it your turn, you can take your pick," then she went shoppin. While she was gone, I ate the whole chicken.
When she got home she seen what I done done and got all kinda pissed off, for some damn reason. She said: "aint, I said you could take your pick!" I said: "That's what I done, Mama, first I picked one half, then the other, see?" She said: "Sayin you can take your pick DON'T mean, you can take both, fool!" That's when the beatin begun.
I still don't git it, ya know?
Relativity Professor (RP): OK, class next problem. Two precious human beings are separating at a relative rate of .5c. A assumes he is motionless, so let's say he's right, we don't want to hurt his feelings or suggest he could possibly be wrong, now, do we?
[Class members start punchin numbers into their calculators, assuming B is travelling at .5c]
RP: Hold on, I aint finished. B assumes he is motionless, so let's say he's right, we don't want to hurt his feelings or suggest he could possibly be wrong. Now, then...
Smartass student (SAS): Hold on, Doc, ya got relative motion between these two guys but you're sayin neither is movin.
RP: Yeah, so?
SAS: So they can't both be right. How can we possibly solve a problem based on these premises?
RP: Nothing in relativity theory does, or would ever, say that both can't be right. It just wouldn't be fair to say one is wrong.
SAS: One of them has to be wrong.
RP: Not so fast, Smartass, there are other ways to resolve this apparent dilemma without disrespecting the claims of either A or B!
SAS: Yeah, like what?
RP: Think about it, dumbass.
SAS: There is no motion, maybe?
RP: Now ya got it. Relativity fully allows for the possibility that any and all appearance of motion is simply illusory. Motion has no feelings, like precious human beings do, so that is the thing to disregard.
SAS: So they are both at rest, and there is no motion, eh? So what's the question, and how would we solve it?
RP: There is question, there is no solution. Motion is an illusion, including the illusory motion you see when you think you're punchin numbers into your calculator. Nothing can not exist, so all is pure Being...all appearance of change is an illusion. As the great Parmenides once said....
SAS: Save it Doc, I'm droppin this class.
Keeping down to the basics:
One Brow said: "If you are accelerating in freefall according to some reference frame, the wine glass does not go anywhere. That's what freefall is."
Wrong again. I have already quoted wiki on this matter. In it's broadest sense, "free fall" means "acting under the influence of gravity alone." Most people don't use it in that broad sense. They use it to mean "moving UNIFORMLY under the influence of gravity alone." You are thinking of the second, colloquial sense of the word.
But in the broad sense, there are two distinct brands of "free fall"
1. Accelerated free fall, and
2. Unaccelerated free fall.
In case one, you will feel "g forces." In case two, you will not, and you will be weightless.
1) This is a contradiction of the equivalence principle. YOu can throw out the EP if you like, but the you throw out pretty much all of relativity theory.
2) The only difference between 1. and 2. is point of view.
3) There is no such thing as "moving uniformly in free-fall" to an observer outside the gracvity well. Whether you are moving toward the center of gravity or in orbit around it, your velocity is not uniform even when the orbit is perfectly circular. Since there are no circular orbits, even your speed is not uniform.
For example, your in a spaceship headed directly toward Jupiter. At some point, you turn off you engines, and allow Jupiter's gravity to pull you in. While you are moving on gravity alone, you release a ball. What do you think *can* happen:
a) For some reason, Jupiter pulls at you with greater force. The ball moves toward Jupiter less quickly. To you, it looks like the ball moves up.
b) For some reason, Jupiter pulls on you less hard than the ball. It seems to move down.
c) Jupiter pulls you and the ball in at the same rate. You see the ball continue to float right beside you as you get pulled in. Inside the spaceship, it doesn't look any different than it might if you were in orbit, or outside Jupiter's gravity well.
How can you feel a g-force when there is nothing pushing you against the g-force, do you think?
"When you discuss coordinate system K, you are looking at one reference frame, and with K' you are looking at a different reference frame. Both reference frames are describing the same relative motion."
This sounds better suited for the Math Geek message board. What is the significance of this statement? I think I understand it, but I also think it's inherently obvious and have no idea why you think it is necessary or pertinent to state it at this time.
It is necessary because of ther confusion you show in the same comment:
"WHAT!? What have I ever said that would make it seem like I think they are seeing different motion?
Again, WHAT!? Are you saying that it is IMPOSSIBLE for either of them to make incorrect assumptions about which one is moving?"
You understand they are seeing the same relative motion. Any assumptions about "which one is moving" is *irrelevant* to relativity theory. It doesn't matter. Relativity theory ignores the concept. You have taken a couple of parenthetical remarks about knowing which twin is really moving, and assumed that is in some way important to getting the correct age difference in the calculation. However, and this is the so-called paradox: it doesn't matter which twin is moving, as long as the earth twin stays in an inertial environment and the ship twin does not.
Your Relativity Professor is obviously very confused. He doesn't understand using different coordinates systems to examine a scenario, and is trying to insist on using two different coordinate systems at the same time. That's like looking at the measurement of the location of a baseball on the field as a angle and distance from home plate (polar coordinates), then using Catesian coordinate on the first and third base lines with first base as the origin, and insisting the using both systems at the same time. Of course you don't use both at the same time. However, whichever coordinate system you use, if you use it correctly, you *will* be able to pinpoint the baseball correctly.
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#ixzz0amGd0GVD
In his famous work on special relativity in 1905, Albert Einstein predicted that when two clocks were brought together and synchronized, and then one was moved away and brought back, the clock which had undergone the traveling would be found to be lagging behind the clock which had stayed put.
One Brow said: You understand they are seeing the same relative motion. Any assumptions about "which one is moving" is *irrelevant* to relativity theory.
If ya don't believe Al and other physicists, maybe you would trust Colton, eh?
Good luck!
I do beleive Einstein and the other physicists. They also say any assumption about which one is moving is not relevant to relativity theory.
In relativity theory, the significant aspect of "then one was moved away and brought back" is only the change in inertia implied by this, a strictly relative phenomenon, and the nmotion itself.
Still, I don't blame you for bailing. It wasn't going to be easy explaining some supposed difference between accelerated and unaccelerated free fall, nor how there is some supposed innate g-force detector that sees senses accelerated free-fall but not unaccelerated free-fall, nor why the Relativity Professor doesn't understand what it means to change coordinate systems. You might have actually had to re-think what you were saying. We can't have that.
One Brow said: "It wasn't going to be easy explaining some supposed difference between accelerated and unaccelerated free fall, nor how there is some supposed innate g-force detector that sees senses accelerated free-fall but not unaccelerated free-fall,"
"When a skydiver first jumps out of the plane he will experience a downward falling sensation which will continue until he reaches terminal velocity which is around 120 mph. Generally this sensation will fade after reaching terminal velocity because he is no longer accelerating."
http://www.streetdirectory.com/travel_guide/39973/extreme_sports/reasons_to_skydive.html
"Skydivers reach terminal velocity (the constant speed of a falling object when the upward drag on the object balances the downward force of gravity) at around 190 km/hour for belly to earth orientations and because they are no longer accelerating towards the ground they do not experience that falling sensation. It is acceleration that causes the strange sensation of “stomach in the throat” that we experience, for example, on a roller coaster ride."
http://www.southafrica.com/blog/the-thrill-of-skydiving-in-south-africa
"If you're studying physics, there are few more exhilarating classrooms than a roller coaster. Roller coasters are driven almost entirely by basic inertial, gravitational and centripetal forces, all manipulated in the service of a great ride....This fluctuation in acceleration is what makes roller coasters so much fun...Normally, all the parts of your body are pushing on each other because of the constant force of gravity. But in the "free-fall" state of plummeting down a hill...the various pieces of your body are not pushing on each other as much. They are all, essentially, weightless, each falling individually inside your body. This is what gives you that unique sinking feeling in your stomach -- your stomach is suddenly very light because there is less force pushing on it. The same thing happens when you drive down a dip in the road in your car or descend in an elevator moving at high speed."
http://www.howstuffworks.com/roller-coaster.htm/printable
Yeah, every schoolboy KNOWS that Einstien done said there is no possible way to detect acceleration, eh? That aint what wiki and all the other examples we looked at said about the "turn-around," but they aint knowwin nuthin. Only YOU know the truth.
One Brow said: "You might have actually had to re-think what you were saying."
This thread has certainly demonstrated that, for some people, re-thinking what they have said is impossible.
One Brow said: "YOu can throw out the EP if you like, but the you throw out pretty much all of relativity theory."
Well, maybe you're gunna wanna throw out all of relativity theory, then. Feel free, but most don't see that necessity.
One Brow said: "Whether you are moving toward the center of gravity or in orbit around it, your velocity is not uniform even when the orbit is perfectly circular."
This is just one reason of several why the EP is not literally true. If you are in a closed, 10' x 10' room in space, gravity will not affect something on one side of the room the same as the other. One is closer to the center of gravity they are both circling.
Then again, maybe you could just read what I have already said about the EP, which shows that it has nothing to do with "free fall," as such. It has to do with acceleration, not free fall. Einstien (contrary to Newton) claimed that an object in orbit was "unaccelerated," i.e., inertial.
Wait... Read what I said? What am I thinkin!?
Of course, another reason why gravity is not truly equivalent to acceleration is because acceleration does not affect time dilation, nor does it impose time contraction effects, like gravity. But, wait, you have already denied what the leading experts on particle acceleration say about that, I spoze.
They hafta be wrong, I'm sure. If non-existent, pseudo-gravity can contract time, like Al suckers some chumps into believing, then I suppose ANYTHING can. That's what makes relativity such as easy topic. Every answer you give HAS to be right, if ya just make up some stuff as ya go along.
Yeah, every schoolboy KNOWS that Einstien done said there is no possible way to detect acceleration, eh?
Yeah, it's not like those sky-divers and roller-coaster riders feel the air flow increase as they move faster, and use that to detect acceleration. Instead, we have AintNoThang's magical free-fall acceleration detection, where you can detect the difference between accelerated and unaccelerated free-fall. How's that work again?
Of course, I would expect you to directly address what I wrote. It's much easier to talk about stuff like skydiving than to actually say how to detect "accelerated free-fall". Why do you think that is?
That aint what wiki and all the other examples we looked at said about the "turn-around," but they aint knowwin nuthin. Only YOU know the truth.
You can cry that I disagree with the wiki examples until the cows come home, and it still won't be true. For, one thing, the turn-around is part of the relative motion, and why the frame of U2 is not inertial in either K or K'. K and K' interpret the turn-around differently, but it's the same event, relatively speaking, in the two frames of reference (aka coordinate systems).
This thread has certainly demonstrated that, for some people, re-thinking what they have said is impossible.
I'm not giving up yet. You just might get there.
Well, maybe you're gunna wanna throw out all of relativity theory, then. Feel free, but most don't see that necessity.
I'm not the one throwing out the EP with talk of different kinds of free-fall.
This is just one reason of several why the EP is not literally true. If you are in a closed, 10' x 10' room in space, gravity will not affect something on one side of the room the same as the other. One is closer to the center of gravity they are both circling.
You could be makeing a coupe of different points here, and I'm not sure which one to pick up. Are you saying there will be a tendency for objects closer to the earth to migrate down to the bottom of the room, a tendency for those near the top to migrate up to the roof, and that this means the EP doesn't work on an object in orbit? Is that what you mean by accelerated free-fall? Is that different from the room, and everything in it, having a very slight spin? Not all acceleration is straight-line. I don't see how the EP is violated here.
Of course, another reason why gravity is not truly equivalent to acceleration is because acceleration does not affect time dilation, nor does it impose time contraction effects, like gravity. But, wait, you have already denied what the leading experts on particle acceleration say about that, I spoze.
That depends on your point of view. U2 reads less time than U1 because it's environment is non-intertial. The environment is non-inertial because of acceleration (in K) or gravity (in K'). Seems like the acceleration is important.
I see your still riffing on the whole "every answer must be right" stuff. Reminds me of a story.
Prof: Now, I want some of you to tell me the location of that ball using polar coordinates from home plate, and others use the Cartesian coordinates at first base.
Student A: In polar coordinates, that ball is at (90*sqrt(2),45).
Student B: In the Cartesian coordinates, that ball is at (0,90).
Prof: Good work.
NoBigDeal: Hey Prof., which of them is wrong?
Prof: They're both right.
NoBigDeal: Naw, they got different numbers. The ball can't be at (90*sqrt(2),45) and at (0,90) at the same time. That don't make no sense.
Prof.: Well, using different coordinate systems, you would expect the numbers to look different for the same location.
NoBigThing: So, which of them coordinate systems is right? We got to have one right answer here.
Prof.: Both answers are right. There's no reason to choose one over the other.
NoBigThing: So I guess you're saying that ball can be anywhere on the field? If you can[t figure out the righ tnumbers, it must be that length has no meaning ...
Talk to Colton about all your novel theories, eh, Eric?
Good luck!
I haven't presented any novel theories, this is all boilerplate stuff.
However, if you want me to submit that list of questions, or any other list, I'll be happy to do so. Here's what I have so far. Let me know if you think there should be any changes.
1. In the twin paradox listed in and http://en.wikipedia.org/wiki/Twin_paradox, does the answer to which twin is younger depend in any way on the notion that the ship twin is moving and the earth twin is stationary, as opposed to looking at relative motion between the ships only?
2. In Einstein's dialog http://en.wikisource.org/wiki/Dialog_about_objections_against_the_theory_of_relativity, in coordinate system K', does U1 experience acceleration?
3. Is there ever a case where acceleration by free fall is not an inertial environment?
4. Pat and Chris are born on widely separated planets in approximately the same rest frame, and Pat is then accelerated to .6c in the general direction of Chris. When Pat passes Chris, both are exactly 12,000 days old. As long as neither accelerates, will you be able to say that Pat will be younger than Chris from then on?
5. Tom and Ron are born on widely separated planets in the same rest frame, and Tom is then accelerated to .6c in the general direction of Ron. At the time Tom accelerated, he and Ron are the same age, according to their identical respective time frames. As long as neither accelerates, will you be able to say that Pat will be younger than Chris from then on?
6. Within relativity theory, can there be there such a thing as a wrong viewpoint to take?
7. Are there distinct things that could be thought of as unaccelerated free-fall and accelerated free-fall?
4 is the same as 5, leave one out. 6. Is meaningless, out of context. Skip it, and ask him to review my (3 related) statements, and your denial thereof, insofar as what SR/GR allow. 3 and 7 relate to insignificant issues, but ask away, if you want to know.
One Brow said: "2. In Einstein's dialog http://en.wikisource.org/wiki/Dialog_about_objections_against_the_theory_of_relativity, in coordinate system K', does U1 experience acceleration?
I especially like this one. He'll probably tell you to simply read what Al says, which has already been pointed out to you twice. Perhaps then you will realize that a question can be satisfactorily answered for you multiple times and you will still treat the issue as being unanswered and uncertain.
"Clock U1 is accelerated in the direction of the positive x-axis until it has reached the velocity v, then the gravitational field disappears again."
That's at least 3 times, but, by all means, ask Colton. He will probably understand and remember what he reads.
You might want to ask him how gravitational fields just "disappear" while you're at it, eh?
One Brow said: "I'm not the one throwing out the EP with talk of different kinds of free-fall...I don't see how the EP is violated here."
The EP does NOT say "gravity is the equivalent of (indistinguishable from) free fall," as you seem to believe. It says that "gravity is the equivalent of (indistinguishable from) ACCELERATION (if, and only if, you are deprived of the ability to see outside of your immediate environment). Einstein equates orbital free fall with an inertial state, i.e., the OPPOSITE of acceleration.
Think about it.
I'm sitting in my hot rod Ford, at a stoplight, and set my 40 oz. bottle of malt liquor on the dash. As soon as it turns green (well, before that actually, but either way...) I mash down on the foot pedal. HARD.
What happens to my 40? It is being accelerated, just like the Ford, aint it? It's in the same reference frame, that of the hot rod Ford, aint it?
I guess I know your answer beforehand--whatever happens is undetectable, because acceleration cannot be detected.
"imagine that an alien spacecraft suddenly attaches a rope to the elevator which is floating in space, and rockets forward, towing the elevator at an acceleration of about 9.8m/s² (the same as the standard acceleration due to Earth’s gravity). You are suddenly thrust back onto the floor of the elevator due to the sudden change in speed and direction."
Hmmm, the guy was just "floating in space," just mindin his own damn bidnizz, and all, and then, whammo! He got accelerated, eh? But he doesn't know it, right? Acceleration can't be detected.
"To them, the sudden acceleration which increases their inertial mass and keeps them standing on the floor of the elevator as it hurtles through space would feel identical to the mass created by the force of gravity on Earth."
He would go from a weightless state, to a situtation which keeps him "standing on the floor." Well, no one would ever know that, I'm sure.
http://physics.suite101.com/article.cfm/the_equivalence_principle
I quoted a source as saying: "imagine that an alien spacecraft suddenly attaches a rope to the elevator which is floating in space, and rockets forward, towing the elevator at an acceleration of about 9.8m/s² (the same as the standard acceleration due to Earth’s gravity)."
Lets just change "alien spacecraft" to "pseudo-gravitional field." Now what? Is the acceleration any different, because a different "force" is causing it? Hmmm...well, let me put it this way...if it's pseudo-gravity, THEN the guy is in....wait for it.....FREE FALL!!!!
The magic incantation has been uttered, now. FREE FALL, I tellya!! THAT changes everything, somehow.
Ya gotta give Al credit for his astute use of champ-bait. Just throw in the magic words, "free fall," and the chumps somehow think acceleration now acts differently.
Why does Al say a satellite in orbit is "inertial?" Well, mainly because he got to playin around and re-defined "straight line" to be a virtual circle, in this case. So the satellite in now changing neither speed NOR direction. Hence it is "unaccelerated" (intertial). It's velocity is unchanging.
How about the clock U1? It is changing speed and probably direction, too. At least one, if not both. It is changing it velocity. It is non-enertial. Call it free fall, call it an alien spaceship, call it "thrusters" call it whatever you want, that's "causing" the acceleration, that don't change nuthin about "whether" it is being accelerated or about the sensations a person might feel when accelerated.
Well, there is one exception, I guess. If I say that acceleration can't be detected, then, by God, it CAN'T be detected. In that case a person don't feel nuthin when accelerated, ya know? Purty simple, actually.
One Brow said: " I don't see how the EP is violated here."
The field aint homogenous, caincha see?
"This statement is called the equivalence principle. One of the consequences: In a reference frame that is in free fall, the laws of physics are the same as if there were no gravity at all - the laws of physics are those of special relativity! So far, so simple. Too simple, in fact, in several respects.
Strictly speaking, all that was said about the equivalence of gravity and acceleration is true only for gravitational fields that are strictly homogeneous... But real gravitational fields are always to a certain extent inhomogeneous...
Tidal effects are what tells a freely falling observer that he is in an inhomogeneous gravitational field, and thus definitely not in gravity-free space."
So, I guess ya can distinguish mere acceleration in space from gravitation after all. Good try, though, Al! Here's the good part:
"By choosing a suitably small elevator and a suitably brief period of observation, one can keep the difference between the laws of physics in that cabin and those of special relativity arbitrarily small."
http://www.aei.mpg.de/einsteinOnline/en/spotlights/equivalence_principle/index.html
What is "suitably small?" Well, a DIMENSIONLESS euclidean point, see? Just the kinda thing I thought you objected to, when Feser said the pythagorean principles is "true." Sure, it may be pure fiction, but still...Math don't care about that!
Really, Eric, given your devotion to your (mis) understanding of the mathematical aspects of relativity theory, to the point where you deny any and all practical and empirical considerations and treat them as totally irrelevent, however valid, you should really abandon this "motto." It kinda misrepresents your true philosophy, I think:
"With formal systems, such as mathematics, you can have certainty and demonstrability, but not reality.
With science, such as physics, you can have reality and demonstrability, but not certainty.
With belief systems, such as Christianity, you can have reality and certainty, but not demonstrability."
For you, your particular choice of a formal system *is* reality, it seems.
Here's the current list:
1. In the twin paradox listed in and http://en.wikipedia.org/wiki/Twin_paradox, does the answer to which twin is younger depend in any way on the notion that the ship twin is moving and the earth twin is stationary, as opposed to looking at relative motion between the ships only?
2. In Einstein's dialog http://en.wikisource.org/wiki/Dialog_about_objections_against_the_theory_of_relativity, in coordinate system K', does U1 experience acceleration?
3. Is there ever a case where acceleration by free fall is not an inertial environment?
4. Pat and Chris are born on widely separated planets in approximately the same rest frame, and Pat is then accelerated to .6c in the general direction of Chris. When Pat passes Chris, both are exactly 12,000 days old. As long as neither accelerates, will you be able to say that Pat will be younger than Chris from then on?
5. Pat sees himself as at rest, Chris sees himself as at rest. Assume Pat is right. Relative to Chris, at least, he is in fact at rest. Chris is therefore wrong. Chris will be younger, even if he thinks Pat is younger, and even if they never meet again. End of story. Assume Chris is right. Relative to Pat, at least, he is in fact at rest. Pat is therefore wrong. Pat will be younger, even if he thinks Chris is younger, and even if they never meet again. End of story. In neither case are P and C "both correct" or "equally correct" in their mutually exclusive assumptions. And all that is a simple matter of SR/GR theory. Those theories do not say "both are correct." On the contrary, both theories say "both can not be correct, one must be incorrect." Is this accurate?
6. Within relativity theory, can there be there such a thing as a wrong viewpoint or frame of reference to use?
7. Tom and Ron are born on widely separated planets in the same rest frame, and Tom is then accelerated to .6c in the general direction of Ron. At the time Tom accelerated, he and Ron are the same age, according to their identical respective time frames. As long as neither accelerates, will you be able to say that Tom will be younger than Ron from then on?
8. Are there distinct things that could be thought of as unaccelerated free-fall and accelerated free-fall?
I'm trying to keep any indications on who agrees with waht position out of the questions.
... you will still treat the issue as being unanswered and uncertain.
No, I treat the answer as being clear and certain: U1 never experiences acceleration is either K or K'. Acceleration in freefall is very different from acceleration by propulsion.
That's at least 3 times, but, by all means, ask Colton. He will probably understand and remember what he reads.
Just for crazy speculative purposes, let's say he answers the question in a way that endorses my opinion. What would your response be? I can guarantee you that I'll be very surprised if he endorses yours, but I will certainly try to find how I was wrong.
You might want to ask him how gravitational fields just "disappear" while you're at it, eh?
Is that important to evaluating the resulots of the relativistic moiton in K'? I don't see how.
The EP does NOT say "gravity is the equivalent of (indistinguishable from) free fall," as you seem to believe. It says that "gravity is the equivalent of (indistinguishable from) ACCELERATION (if, and only if, you are deprived of the ability to see outside of your immediate environment). Einstein equates orbital free fall with an inertial state, i.e., the OPPOSITE of acceleration.
I agree with everything you just said, except for "as you seem to believe". Even further, Einstein equates not just orbital free-fall, but all free-fall with an inertial state. More on this below.
I'm sitting in my hot rod Ford, at a stoplight, and set my 40 oz. bottle of malt liquor on the dash. As soon as it turns green (well, before that actually, but either way...) I mash down on the foot pedal. HARD.
What happens to my 40? It is being accelerated, just like the Ford, aint it? It's in the same reference frame, that of the hot rod Ford, aint it?
If your bottle is in a bottle holder on the dash, the car will push the bottle holder, possibly with a force of 1G. Otherwise, the bottle will not move with the car. From the bottle's point of view, the car movew out from under it. From the car's point of view, and probably the driver's, the bottle flies off the dash.
What do you think "being in the same reference frame" means? A reference frame is just a fancy version of a coordinate system. Everything is in every reference frame.
I guess I know your answer beforehand--whatever happens is undetectable, because acceleration cannot be detected.
Acceleration is detected by the feeling of something pushing against us.
Hmmm, the guy was just "floating in space," just mindin his own damn bidnizz, and all, and then, whammo! He got accelerated, eh? But he doesn't know it, right? Acceleration can't be detected.
He can certainly detect being pushed by the floor of the elevator.
Lets just change "alien spacecraft" to "pseudo-gravitional field." Now what? Is the acceleration any different, because a different "force" is causing it? Hmmm...well, let me put it this way...if it's pseudo-gravity, THEN the guy is in....wait for it.....FREE FALL!!!!
The magic incantation has been uttered, now. FREE FALL, I tellya!! THAT changes everything, somehow.
If you are in free-fall, you are moving at the same rate as the floor. It doesn't push against you anymore. That is the difference between acceleration in free-fall and acceleration by propulsion: in the former, nothing pushes/pulls you. There is no yank, no tug.
Ya gotta give Al credit for his astute use of champ-bait. Just throw in the magic words, "free fall," and the chumps somehow think acceleration now acts differently.
Acceleration doesn't "act" at all, but we percieve different environments differently.
Why does Al say a satellite in orbit is "inertial?"
"Inertial" is an empirical state, not an ontological one. Once you get that, you might see why the rest of your comment was completely off-point.
One Brow said: " I don't see how the EP is violated here."
The field aint homogenous, caincha see?
The EP makes no claim that any arbitrarily large field will be homogenous. It describes local effects only.
Tidal effects are what tells a freely falling observer that he is in an inhomogeneous gravitational field, and thus definitely not in gravity-free space."
So, I guess ya can distinguish mere acceleration in space from gravitation after all. Good try, though, Al! Here's the good part:
So, you are relaying on the tidal effects you see in orbit to claim that when you are in free-fall approaching a planet directly, and don't experience tidal effects, you can tell you are in a gravity well?
If anything, this is saying that being in orbit is not inertial, but accelerating what looks like a straight line would be, which is the opposite of what you have been trying to say.
Really, Eric, given your devotion to your (mis) understanding of the mathematical aspects of relativity theory,
Given your devotion to a misunderstnding of the most basic aspects of relativity theory, this just gave me a chuckle.
One Brow said: "I'm trying to keep any indications on who agrees with waht position out of the questions."
You are not succeeding. But whatever. Talk to Colton, or whoever you are willing to listen to and consider in good faith. The main questions here are 1 and 4. 6 would be, if it were in any way meaningful. But ask him lots of questions, once you get his answers. I don't even understand #1 insofar as it has this phrase: "as opposed to looking at relative motion between the ships only?," but by all means, explain exactly what you mean to him.
You might want to ask him how gravitational fields just "disappear" while you're at it, eh?
You: "Is that important to evaluating the resulots of the relativistic moiton in K'? I don't see how."
It might be important in terms of you getting even the slightest grasp on reality, as opposed to math with absolutely no regard for the empirical world. The whole thing is so bogus as to be embarrassing for Al.
One Brow said: "The EP makes no claim that any arbitrarily large field will be homogenous. It describes local effects only."
Who's talkin about "arbitrarily large." We're just talkin about the example Al himself used when "demonstrating" the ability to distinguish, i.e., the "lab" in orbit.
One Brow said: "So, you are relaying on the tidal effects you see in orbit to claim that when you are in free-fall approaching a planet directly, and don't experience tidal effects, you can tell you are in a gravity well?"
No, I'm not sayin that at all. I'm sayin you don't experience tidal effects when you are NOT in a "gravity well" (whatever the hell that is). Not when you are simply moving inertially (at a uniform velocity) in deep space free from all gravitational influences. The two can be distinguished, get it?
Al's only claim about "free fall" is that you do not have a sense of "weight." He does not say you cease to have all senses, and could not detect acceleration.
Re-read the roller coaster excerpts. A person in orbit "does" have weight. Depending on the altitude of the orbit, it may be 95% or more of the weight he has on earth. The earth is still "pulling" on him, and he has not "escaped earth's gravitational field." But he has a momentum left over from the speed which originally accelerated him which "offsets" his gravitational weight, giving him the "sensation" of weightlessness, even when he is not truly weightless. Same thing happens on coasters.
The real point is that, as the sources I have cited clearly indicate and explain, sudden changes in velocity can always be detected by a person (unless negligible). If nothing else, in "free fall" one's "insides" initially feel scrambled, because they are changing speeds. Each organ in your body has it's own, independent mass (resistance to acceleration), just like the 40 on the car dash has it's own mass.
You may, for example, actually be decelerating (relative to the earth) but feel that you are accelerating when in a plane that has been decelerating at a constant rate, but then the rate of deceleration decreases. "You" are "accelerating" with respect to the plane, not the earth. You do NOT notice constant velocity, only a change in velocity (acceleration).
In a space station, two clocks at different sides of the room would run at different rates. There are simply "ways" to tell if you are in orbit or simply in an inertial state which is unaffected by gravitation, despite Al's intellectual insight (and it was a good one, don't git me wrong). But the two are simply not "equivalent," even if they very nearly the same.
One Brow said: "Given your devotion to a misunderstnding of the most basic aspects of relativity theory, this just gave me a chuckle."
Keep chucklin, Chucklehead. But then go talk to Colton.
One Brow said: "If anything, this is saying that being in orbit is not inertial, but accelerating what looks like a straight line would be, which is the opposite of what you have been trying to say."
As I have repeatedly said, being in orbit is NOT inertial motion, according to SR (and Newton). It is "defined" as inertial in GR because the orbital path is now DEFINED as a "straight line." The phenomenon is exactly the same, however you define it. If you are willing to call circles "sraight lines," then GR is for you, dump SR.
SR: A body is orbit is constantly accelerating, even though its rate of speed remains constant, because it DIRECTION is constantly changing.
GR: A body is orbit is never accelerating. It's speed is constant and it never changes DIRECTION. It is going in a "straight line," and is therefore inertial (unaccelerated).
Acceleration: A change in velocity
Velocity: a vector measurement of the rate and direction of motion
We done went through all this when we were talking about GPS, and you claimed that the orbiting satellites were "accelerating," remember?
I suggested: You might want to ask him how gravitational fields just "disappear" while you're at it, eh?
You responded: "Is that important to evaluating the resulots of the relativistic moiton in K'? I don't see how."
Actually, in many ways this goes to the very heart of your misunderstanding...you equate a formal mathematical system with "reality," and care not in the least about empirically ascertainable facts.
Remember, Al himself never said that inertial motion in deep space CANNOT be distinguished from free fall in orbit. He claimed you could not distinguish it ONLY IF you were virtually deprived of all means to empirical input. A guy in orbit in a capsule with windows would NEVER think he was in inertial motion in deep space. He would simply look out the window, see the earth, and immediately realize that such a massive body would have to be causing gravitational effects on his ship.
In everyday cases, gravity CAN, easily, be distinguished from acceleration, if you are not deceived or deprived of all your senses.
Granted, MATH doesn't care about that. But scientists do. That is why so many have basically scoffed at Einstiens "pseudo-gravitational" field "explanation" of the twin paradox (which doesn't even "solve" the paradox, it simply re-affirms it via absurd means). You, however, eat it up. You claimed to "eat paradoxes for breakfast." I believe you. Lunch and dinner, too, with all kinda snacks in between 24/7, even. The problem is that you forget to chew. You simply swallow them whole and incorporate them into your set of "known truths."
There you are...in free fall, orbiting the earth. Suddenly, and magically, an object with the mass of the SUN materializes 1000 miles away. Suddenly, you are in high-velocity, accelerated "free fall" towards it. What's extra magic is that you wouldn't even know you were moving, eh?
Yeah, right.
You have mismatched these two concepts:
1. A person orbiting in free fall cannot distinguish his sensations from those he would feel if he were moving UNIFORMLY in a straight (euclidean) line in deep space.
2. A person in a gravitational field, standing on earth, cannot distinguish his sensations from those he would feel if he were ACCELERATING in deep space at a rate of acceleration equal to 1 g.
The one who is accelerating cannot drop his wine glass and have it float beside him, get it?
On the other hand, the orbiting person is NOT accelerated, as GR defines the term, anyway.
In his example, Einstien explicitly acknowledges that clock U1 is "accelerating," and then throws in the term "free fall." In this sense, the phrase "free fall" only serves to specifiy the cause of the acceleration (gravitation, as opposed to material forces).
He uses the term "free fall" in its broadest sense, which merely means moving as a result of gravitational forces alone.
This is NOT the (unaccelerated) inertial "free fall" of one in orbit. It is accelerated free fall, and hence the equivalent of being in a gravitational field WITHOUT some offseting sideways momentum, like a person in orbit has. It is, in other words, being in deep space but NOT moving uniformly, but rather accelerating at a constant rate, which gives one the sensation of "having weight." Again, the nature of the force does NOT determine whether you are moving uniformly (inertially, without acceleration) or non-uniformly (non-inertially, with acceleration). "Free fall" serves to specify the nature of the force (graviation) causing the acceleration, and no more. "Free fall" is NOT synonymous with "inerta" or "lack of acceleration."
You, Eric, tend to deduce all your empirical conclusions from your (often limited, or mistaken) idea of what a word "means." Very unscientific of you, notwithstanding your constant claims to being an "empiricist" who bases his conclusions on "science."
One Brow said: "Instead, we have AintNoThang's magical free-fall acceleration detection, where you can detect the difference between accelerated and unaccelerated free-fall. How's that work again?"
Read much, Eric? It was explained just a post or two before you asked the question:
"But in the "free-fall" state of plummeting down a hill...the various pieces of your body are not pushing on each other as much. They are all, essentially, weightless, each falling individually inside your body. This is what gives you that unique sinking feeling in your stomach -- your stomach is suddenly very light because there is less force pushing on it. The same thing happens when you drive down a dip in the road in your car or descend in an elevator moving at high speed."
Comprehende?
One Brow said: "Inertial" is an empirical state, not an ontological one. Once you get that, you might see why the rest of your comment was completely off-point."
No, "inertial" is a strictly theoretical, not empirical, concept, which can be defined in different ways and which, in fact, is a very baffling matter within the context of relativity and physics in general. Once you have chosen a theoretical definition which you like, then you can seek to confirm, empirically, if a given situation meets your definition of "inertial," but this is problematic. To quote Al himself on the topic:
"The weakness of the principle of inertia lies in this, that it involves an argument in a circle : a mass moves without acceleration
if it is sufficiently far from other bodies; we know that it is sufficiently far from other bodies only by the fact that it moves without acceleration."
http://www.archive.org/stream/meaningofrelativ00eins/meaningofrelativ00eins_djvu.txt
Sometimes, ya just stop noticin acceleration because ya done passed out, ya know?:
"If sustained for more than a few seconds, 4 to 6 g is sufficient to induce blackout."
But at least then, if ya stop acceleratin, ya come to. Other times, ya never notice any acceleration ever again, though:
"Extreme acceleration can lead to death. The acceleration during the crash that killed Diana, Princess of Wales, in 1997 was estimated to have been on the order of 70 to 100 g, which was intense enough to tear the pulmonary artery from her heart — an injury that is nearly impossible to survive."
http://physics.info/acceleration/
So, in some cases you're right, it seems; sometimes ya just don't detect acceleration.
You are not succeeding.
Despite all your help with the wording? Well, they have been sent, since you offered no further objections.
Again, for the record, my answers are no to all 8 questions as currently phrased, and as far as I can tell yours are all yes. Let me know if you thnk any of them should be a "no".
I noticed that, while I pledged to reconsider should colton not agree with me, I did not see you say something similar.
But whatever. Talk to Colton, or whoever you are willing to listen to and consider in good faith.
I listen to you in good faith, despite your misunderstandings.
I don't even understand #1 insofar as it has this phrase: "as opposed to looking at relative motion between the ships only?," but by all means, explain exactly what you mean to him.
Looking at the relative motion only refers to looking at what can be measured (relative velocities, acceleration experienced, etc.).
You might want to ask him how gravitational fields just "disappear" while you're at it, eh?
You: "Is that important to evaluating the resulots of the relativistic moiton in K'? I don't see how."
It might be important in terms of you getting even the slightest grasp on reality, as opposed to math with absolutely no regard for the empirical world. The whole thing is so bogus as to be embarrassing for Al.
So, you are asking how the gravitational fields appear or disappear because you change a coordinate system, and *I* am the one following the math with no regard for the empirical world? I have trying to explain to you that choosing K' over K makes no difference to the reality. *chuckle*
Who's talkin about "arbitrarily large." We're just talkin about the example Al himself used when "demonstrating" the ability to distinguish, i.e., the "lab" in orbit.
If you are insistent on 10' or even 1', that is an arbitrarily large size.
No, I'm not sayin that at all. I'm sayin you don't experience tidal effects when you are NOT in a "gravity well" (whatever the hell that is). Not when you are simply moving inertially (at a uniform velocity) in deep space free from all gravitational influences. The two can be distinguished, get it?
You do experience the equivalent of tidal effects when you are rotating slowly in deep space free from gravitational influences. A gravity well is the part of space where a mass have a measurable effect.
Al's only claim about "free fall" is that you do not have a sense of "weight." He does not say you cease to have all senses, and could not detect acceleration.
There is no sense that can detect acceleration in free fall. You can only detect resistance to acceleration.
The real point is that, as the sources I have cited clearly indicate and explain, sudden changes in velocity can always be detected by a person (unless negligible). If nothing else, in "free fall" one's "insides" initially feel scrambled, because they are changing speeds.
Free-fall means that your organs are no longer haning on each other (as the lungs hang off the ribs, for example), so of course that feels scrambled. It's the exact same scrabling you would feel in an environment with no acceleration and no gravity.
Each organ in your body has it's own, independent mass (resistance to acceleration), just like the 40 on the car dash has it's own mass.
In free-fall, gravity affects all of these organs in exactly the same way, so they still don't hang off each other no matter what the strength of the gravitational field is.
In a space station, two clocks at different sides of the room would run at different rates.
Yes, the EP does not refer to arbitrarily large regions. Got it.
As I have repeatedly said, being in orbit is NOT inertial motion, according to SR (and Newton).
You keep saying this without understanding it.
SR: A body is orbit is constantly accelerating, even though its rate of speed remains constant, because it DIRECTION is constantly changing.
GR: A body is orbit is never accelerating. It's speed is constant and it never changes DIRECTION. It is going in a "straight line," and is therefore inertial (unaccelerated).
*chuckle*
We done went through all this when we were talking about GPS, and you claimed that the orbiting satellites were "accelerating," remember?
Yes, indeed.
I suggested: You might want to ask him how gravitational fields just "disappear" while you're at it, eh?
You responded: "Is that important to evaluating the resulots of the relativistic moiton in K'? I don't see how."
Actually, in many ways this goes to the very heart of your misunderstanding...you equate a formal mathematical system with "reality," and care not in the least about empirically ascertainable facts.
As long as you think the empirically ascertainable facts that realtivity theory uses are different between K and K', your complaints that I am somehow confusing a mathematical formality with reality contain a special irony that I could never script.
Remember, Al himself never said that inertial motion in deep space CANNOT be distinguished from free fall in orbit. He claimed you could not distinguish it ONLY IF you were virtually deprived of all means to empirical input.
Empirical output outside your local surroundings. Yoou have access to any local empirical information at all.
In everyday cases, gravity CAN, easily, be distinguished from acceleration, if you are not deceived or deprived of all your senses.
Not locally.
That is why so many have basically scoffed at Einstiens "pseudo-gravitational" field "explanation" of the twin paradox (which doesn't even "solve" the paradox, it simply re-affirms it via absurd means).
You have scoffed. All the scientists so far have taken the time to explain the equivalent of K' because they are not scoffing at it, rather it has a couple of important points to make. You could compare that to LET, which is pretty much ignored in these explanations.
You simply swallow them whole and incorporate them into your set of "known truths."
You choke on the paradox, spit it back out, and complain about the people who can digest them.
There you are...in free fall, orbiting the earth. Suddenly, and magically, an object with the mass of the SUN materializes 1000 miles away. Suddenly, you are in high-velocity, accelerated "free fall" towards it. What's extra magic is that you wouldn't even know you were moving, eh?
First, tell me what you can experience locally that does tell you about it.
You have mismatched these two concepts:
1. A person orbiting in free fall cannot distinguish his sensations from those he would feel if he were moving UNIFORMLY in a straight (euclidean) line in deep space.
2. A person in a gravitational field, standing on earth, cannot distinguish his sensations from those he would feel if he were ACCELERATING in deep space at a rate of acceleration equal to 1 g.
The one who is accelerating cannot drop his wine glass and have it float beside him, get it?
Not if he is accelerating by propulsion. If he is accelerating by gravity, what stops the wine glass from moving parallel to him, basically looking to him like it is floating next to him?
This question is important enough that I will keep repeating it until you answer it.
In his example, Einstien explicitly acknowledges that clock U1 is "accelerating," and then throws in the term "free fall." In this sense, the phrase "free fall" only serves to specifiy the cause of the acceleration (gravitation, as opposed to material forces).
He uses the term "free fall" in its broadest sense, which merely means moving as a result of gravitational forces alone.
Correct.
This is NOT the (unaccelerated) inertial "free fall" of one in orbit. It is accelerated free fall, and hence the equivalent of being in a gravitational field WITHOUT some offseting sideways momentum, like a person in orbit has.
Pure, utter, meaningless drivel.
It is, in other words, being in deep space but NOT moving uniformly, but rather accelerating at a constant rate, which gives one the sensation of "having weight."
Acceleration by propulsion, sure. Acceleration by gravity is different.
You, Eric, tend to deduce all your empirical conclusions from your (often limited, or mistaken) idea of what a word "means." Very unscientific of you, notwithstanding your constant claims to being an "empiricist" who bases his conclusions on "science."
How completely unlike you, who is in no way relying on the definition of acceleration to state what a experience of acceleration in free-fall must be like, right? *chuckle*
One Brow said: "Instead, we have AintNoThang's magical free-fall acceleration detection, where you can detect the difference between accelerated and unaccelerated free-fall. How's that work again?"
Read much, Eric?
Yes. But you understand this so badly, that there is very little meaning in what you type.
It was explained just a post or two before you asked the question:
"But in the "free-fall" state of plummeting down a hill...the various pieces of your body are not pushing on each other as much. They are all, essentially, weightless, each falling individually inside your body. This is what gives you that unique sinking feeling in your stomach -- your stomach is suddenly very light because there is less force pushing on it. The same thing happens when you drive down a dip in the road in your car or descend in an elevator moving at high speed."
Comprehende?
Yes. In free-fall, just like in an inertial environment, your organs don't hang off of each other. However, that's a way they are alike, as opposed to unalike.
No, "inertial" is a strictly theoretical, not empirical, concept, ... To quote Al himself on the topic:
"The weakness of the principle of inertia lies in this, that it involves an argument in a circle : a mass moves without acceleration
if it is sufficiently far from other bodies; we know that it is sufficiently far from other bodies only by the fact that it moves without acceleration."
If you think Einstein was saying the problem was with the concept of inertia itself in that sentence, I can only say this shows how out-of-your-depth you are.
Sometimes, ya just stop noticin acceleration because ya done passed out, ya know?:
"If sustained for more than a few seconds, 4 to 6 g is sufficient to induce blackout."
Acceleration by propulsion, not gravity.
acceleration during the crash that killed Diana,
Acceleration by brick wall, not gravity.
I said: The one who is accelerating cannot drop his wine glass and have it float beside him, get it?
You responded: "Not if he is accelerating by propulsion. If he is accelerating by gravity, what stops the wine glass from moving parallel to him, basically looking to him like it is floating next to him?"
You say: "This question is important enough that I will keep repeating it until you answer it."
You will repeat the question even after a thousand experts answer it for you, because it apparently conflicts with your misunderstaning of something a high school science teacher told you once. No amount of explanation, undeniable fact, common sense, or any other means of persuasion that rational people find compelling will EVER dissuade you from something you have come to believe and think must therefore be indisputably true.
If you want an answer, drop your wineglass. You are "accelerating by gravity" as you type.
I will await your posting of your findings after discussing your novel ideas with Colton before saying more. I have had enough of the arrogant ignorance for now.
I'm in a gravitational field, but I'm not in free-fall.
When a person is accelerating in free-fall and drops a wine glass, waht stops the glass from floating next to him?
If I ask a 1000 experts, they will tell me that the wine glass will float next to him, fom what I can tell. So, having a 1000 experts explain this to me probably won't change much regarding my opinion, I already agree with them. I am waiting for you to tell me why it doesn't.
One Brow said: "I'm in a gravitational field, but I'm not in free-fall."
I've told you 10 times. The "sensation of weightlessness" is not synonomous with "gravity-free." Acceleration IS acceleration, whatever the cause. You apparently think the very words themselves, "FREE FALL, I tellya!," are magical and have something independent you tell you about acceleration and physiology. You can "feel weightless" and detect acceleration at the same time, despite what have been told. Read it all again, without the sneering arrogance.
Again, your statement was this: "If he is accelerating by gravity, what stops the wine glass from moving parallel to him, basically looking to him like it is floating next to him?"
Where is "free fall" mentioned there? You are simply referring to "acceleration by gravity" which you apparently think is, and can only be, free fall. You are confusing free fall with a lack of detectable acceleration, for whatever reason.
Do you care to offer any explanation for why something "accelerating by gravity," magically produces NON-DETECTABLE acceleration? I didn't think so. Your posts are short on logic, explanation, and understanding while extremely long on loud, unsupported assertion. You reject or ignore all reason and facts if that's what it takes. Now I think I know what you meant by denialism.
I have been told, and once believed, that if you shot a cannonball into the sky with an extremely high velocity (but less than escape velocity) it would "settle into orbit," and never return to earth because the curvature of the earth would prevent it from doing so (given it's inertial momentum from the initial blastoff).
It is now my understanding that this statement is false. If it reaches a velocity exceeding escape velocity, it will just keep on going. If not, it will just fall back to earth.
In order to put an object into orbit, a SECOND accleration boost is needed, one that directs it "sideways." The inertial momentum so given, when COMBINED WITH the pull of the earth's gravity, gives one the sensation of weightlessness, just like a roller coaster ride can do, but the astronaut in orbit is NOT truly weightless. As I said before, he has not escaped the earth's gravitational field, and he still has weight, but the angular momentum creates the illusion of weightlessness.
In short, although it's motion is frequently called "free fall," a satellite in orbit is not responding to "gravity alone"(and hence does not comply with the strict definition of free fall) given its accelerative history.
But that's not even what this issue is about. It's simply about Al's example where you said that "free fall" meant that the acceleration in that example could not be detected. A skydiver can let go of a ball in his hand and it will "float" next to him. He does not feel "weight," and he cannot separately detect the "force of gravity" because there is nothing resisting that force. But that doesn't mean he can't feel ANYTHING at all.
In Al's example, the guy (clock) was initially truly inertial (not being acted upon by any forces, gravitation or otherwise). Then he was SUDDENLY subjected to extreme acceleration. That is no different than being accelerated by a "thruster," despite your insistence to the contrary. The ACCELERATION (not the gravity or the "free fall") would be the same as it is only earth, if the g force was one. If it was 4-6, he would black out. Too high, and he would simply die.
As I posted:
"There you are...in free fall, orbiting the earth. Suddenly, and magically, an object with the mass of the SUN materializes 1000 miles away. Suddenly, you are in high-velocity, accelerated "free fall" towards it. What's extra magic is that you wouldn't even know you were moving, eh?
Yeah, right."
I said: "He does not feel "weight," and he cannot separately detect the "force of gravity" because there is nothing resisting that force. But that doesn't mean he can't feel ANYTHING at all."
"For us animals evolved to function in g=9.8 m/s2, living in g=0 is extremely unpleasant. The early space program focused obsessively on keeping the astronaut-trainees in perfect physical shape, but it soon became clear that a body like a Greek demigod's was no defense against that horrible feeling that your stomach was falling out from under you and you were never going to catch up. Our inner ear, which normally tells us which way is down, tortures us when down is nowhere to be found...Worse than nausea are the health-threatening effects of prolonged weightlessness. The Russians are the specialists in long-term missions, in which cosmonauts suffer harm to their blood, muscles, and, most importantly, their bones."
http://www.lightandmatter.com/html_books/1np/ch03/ch03.html#Section3.7
"Free fall describes any motion of a body where gravity is the only or dominant force acting upon it, at least initially. Since this definition does not specify velocity, it also applies to objects initially moving upward. Although strictly the definition excludes motion of an object subjected to other forces such as aerodynamic drag, in nontechnical usage falling through an atmosphere without a deployed parachute or lifting device is also referred to as free fall."
http://en.wikipedia.org/wiki/Free_fall
It is generally conceded that uniform motion cannot be detected (such as the earth motion around the sun), as far as the senses go. NOBODY that I've ever heard of says that non-uniform (accelerated) motion cannot be detected via organic senses. You see there where is says: "this definition does not specify velocity?" The definition of free fall does not, per se, tell you whether you are in accelerated or uniform motion.
wiki: "Examples of objects in free fall include:
An object thrown upwards or a person jumping off the ground at low speed (i.e. as long as air resistance is negligible in comparison to their weight). Technically, the object or person is in free fall even when moving upwards or instantaneously at rest at the top of their motion, since the acceleration is still g downwards. However in common usage "free fall" is understood to mean downwards motion."
He is in "free fall" even when at rest, even when resisting gravity by moving upwards (the impetus imparted by the "jumping" acceleration of the legs), and even when he once again descends under the force of gravity alone. Your *special* definition of "free fall" aint quite up to par, know what I'm sayin (and have already repeatedly said, beginning many posts back)?
"You should also note that an object doesn't have to be falling to be in free fall - if you throw a ball upward its motion is still considered to be free fall, since it is moving under the influence of gravity."
http://www.batesville.k12.in.us/physics/phyNet/mechanics/Kinematics/FreeFallIntro.html
It is one thing to be confused about the meaning of a term. It is quite another to deny all logic, evidence, reason, and fact which seems to conflict with one's mistaken definition, no matter how many times such things are expressly explained to you. As I said, you DEDUCE (not observe) your so-called "empirical facts" from your pre-conceived ideas/definitons. If your definition (or your concept of what it implies) is wrong, well, then, so much worse for the "truth." Truth CANNOT be inconsistent with your a priori premises, so empirical facts simply are not facts, in your mind. If they are acknowledged to be facts, then they obviously support, rather than undermine, your mistaken conceptions, for example:
"Yes. In free-fall, just like in an inertial environment, your organs don't hang off of each other. However, that's a way they are alike, as opposed to unalike."
I said: "You can "feel weightless" and detect acceleration at the same time, despite what have been told."
I've already given you a number of examples of this, but here's another. They now think that the so-called "space sickness" which (despite early denials by astronuat who didn't want to be expelled from the program) about 90% of astronaut crews experience is a form of "motion-sickness," or sea-sickness." As I understand it, the inner ear can detect lateral acceleration which tells it that it is moving. If the eye becomes fixed, by reading book while riding in a car, for example, it suggests to the brain that you are "not moving," and internal distortions arise.
With astronauts in so-called "free fall" the lateral acceleration which put them into space (or orbit, as the case may be) still experience this "movement due to acceleration" notwithstanding that they "seem" to be just floating, motionless. Just another reason why arbitrary mathematical "co-ordinate systems" cannot fully account for reality or human experience. The guy blasted into space really "is" accelerated, however you may choose to look at this situation from a math perspective.
I've told you 10 times. The "sensation of weightlessness" is not synonomous with "gravity-free."
I have agreed, or at least not disagreed, every time. Feel free to keep repeating it, though.
Do you care to offer any explanation for why something "accelerating by gravity," magically produces NON-DETECTABLE acceleration?
Sure, if you missed it before. It's not detectable because every item near you is under the exact same graviational effects you are, so their motion will match yours unless diverted. When you are acelerated by a car, or a rocket, or a brick wall, you are accelerated by something pushing part of you, and you feel that one part pushing other parts of you. In free fall, no part of you pushes against anyh other part. There is no inertial resistance different from your own with which to detect the acceleration.
When a person is accelerated only by gravity, and releases a wine glass, what stops the wine glass from floating next to him, according to you?
In short, although it's motion is frequently called "free fall," a satellite in orbit is not responding to "gravity alone"(and hence does not comply with the strict definition of free fall) given its accelerative history.
Free-fall is a local event and description. The prior accelerative history does not affect whether a satellite in orbitis currently in free-fall.
Then he was SUDDENLY subjected to extreme acceleration. That is no different than being accelerated by a "thruster," despite your insistence to the contrary.
When you are accelerated in a sitting position by a rocket, your spine is pushed by the rocket, your ribs are pushed by your spine, your lungs are pushed by the ribs, etc. When the acceleration is too high, the ribs can't transfer the energy from back to front well enough to keep up, and the transfer to your lungs is also inefficient. This can result in ribs cracking and lungs tearing. By contrast, when you are accelerated by gravity alont, without even friction to slow it down, your spine, ribs, and lungs are all accelerated together at the same rate. Not one part of your body moves the other. There is no crush effect because nothing is moving against each other.
Your *special* definition of "free fall" aint quite up to par ...
I am using the same definition, and talking about the same phenomenon, as all those articles.
By the way, all those effects you are discussing regarding what happens to people in free-fall, who lose their sense of gravity? That's exactly what would happen on a long space flight when the rockets were not firing (an inertial environemnt). You are actually saying that free-fall is an inertial environment,empirically.
Part of the confusion no doubt arises from equivocal uses of such terms as "weight" and "gravity." For example, I quoted an excerpt from above which said: "For us animals evolved to function in g=9.8 m/s2, living in g=0 is extremely unpleasant."
He uses the term "g=0" or "zero gravity." But this is a misnomer. No objects orbiting earth are operating at zero gravity. Another confusion is between weight, properly defined, as the force gravity exerts on an object, and "apparent weight," i.e., weight as subjectively experienced, or "felt" (which pertains to sensing a resistance to the acceleration caused by gravity).
Orbiting astronauts experience a false sense of weightlessness only because the difference in acceleration between them and their ship is zero (while the gravity exerted upon them by the earth is far from zero). But again, they are not truly in "free fall," they are merely being accelerated at high speeds in a direction perpendicular to the earth IN ADDITION to being subjected to gravity).
Since, zero weight, properly defined, would imply zero gravity, people start equivocally equating zero APPARENT weight with zero ACTUAL gravity. Confused thinking naturally follows.
Weight is an entirely distinct concept from acceleration. A person in free fall does not "feel" his weight, but he is still accelerating under the influence of gravity, i.e., he still has weight, properly defined, even though his apparent weight is zero.
If free fall is defined as being subjected only to a gravitational force, and no other, and if you believe in the equivalence principle (gravity = acceleration), then you MUST say that an object is free fall is being accelerated, whether one feels a resistance to that acceleration (i.e., feels weight) or not.
But again, our question was not about "free fall," nor weight (whether actual or apparent) originally. The question was simply about whether a person can detect acceleration caused by gravity alone (free fall). Sudden shifts in acceleration (as Einstein has in his example) can, and are routinely, detected by anyone with senses. This is a different question than whether he can subjectively "feel" his weight.
How can a person go FROM a state free fall INTO a state of free fall? This is what Einstien is suggesting happens. Take my example from before, but change it slightly. Take a person high in space who is constantly accelerating straight down towards earth and an ever-increasing velocity, with no offsetting lateral velocity. He is in "true" (not merely apparent) free fall. Now suppose an object which is much more massive than earth magically appears and pulls him in the opposite (or any different) direction. Now we have two opposing forces, each supposedly putting him in "free fall." Can his change of direction and speed be detected? Yeah, and this was the whole point of the "Stella turn-around" where she "doesn't move" during the turn-around. She still supposedly feels all the inertial forces that she did when putting on her thrusters, without gravity. She is caught between two opposing, but unequal, accelerative forces, that of her thrusters, still on, and the greater acceleration of the magically appearing pseudo-gravitational field. The result is that she experiences an inertial net force.
Free fall, when defined as being subjected to gravitational "forces" alone, implicitly PRESUPPOSES a single source of gravitional acceleration, not multiple sources, so this just constitutes more equivocation on the term "free fall." But again, the original question was not "what is free fall?" It was can a sudden change in velocity (acceleration) be detected. The answer is, and has always been, "yes," as far as I know, at least if the acceleration in non-negligible.
This is, in fact, the whole presumption underlying the contention that the experiences of the twins in the paradox are not equivalent. To recap that "resolution:"
"SR does not declare that all frames of reference are equivalent, only so-called inertial frames. 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."
http://math.ucr.edu/home/baez/physics/Relativity/SR/TwinParadox/twin_intro.html
One Brow said: "Free-fall is a local event and description. The prior accelerative history does not affect whether a satellite in orbitis currently in free-fall"
Two comments here:
1. I used the term acclerative history to indicate the fact that objects in orbit around earth have relatively large perpendicular speeds relative to the earth (at low altititudes about 17,000 mph). So in that case it is not just the "history," it is the ongoing state of affairs. That said, all objects presumably have a prior acclerative history. Arbitrarily choosing to ignore that history when defining a "inertial" state is just that...arbitrary, for definitional purposes, without regard to objective reality.
2. You try to equate "local" with "not arbitrarily large," but that is nothing short of sophistic word-play. A gravational field is not "uniform" EXCEPT with respect to the non-existent one-dimensional "objects" (aka "points") which you tried to take Feser to task about (i.e., "euclidean geometry is not real"). Of course, in the very next breath you are pontificating about the "true" nature of space, assuming that Reimannian geometry is "real." Why the double standard?
One Brow said: "By the way, all those effects you are discussing regarding what happens to people in free-fall, who lose their sense of gravity? That's exactly what would happen on a long space flight when the rockets were not firing (an inertial environemnt). You are actually saying that free-fall is an inertial environment,empirically."
I'm not saying any such thing necessarily. People on a "long space flight" are still moving, relative to their earth environment, whether they feel themselves to be "motionless" (because their rate of speed is uniform) or not. If he's not looking out the window, a passenger may not "feel" his motion, in a general sense. But their bodies apparently know, and can detect, this in subtle ways.
Anyone riding in a car is "truly" accelerated with respect to the earth, despite the strictly theoretical possibility of "viewing" them as motionless. That's why they call it "motion sickness," ya know?
But that is beside the real point here, which is that accelerated motion, especially sudden acceleration, can be detected, whether uniform motion can be or not.
Of course, needless to say, uniform motion can easily be detected once one looks out the window. It's just that, without additional information, it is hard to say who is moving, because that is not always obvious from subjective sensation alone.
Another point about accelerative history. Two spaceship are cruising, side-by-side, at the same speed for, say a year. One radios to another than he is going to turn on his thrusters, and accelerate until he gets 100 miles ahead.
Everyone involved, on both ships, knows who is "really" going faster when he accelerates. The non-accelerating ship feels no acceleration, while the other does. But how about a guy on the uniformly-moving ship who was taking a a nap, but wakes up, and looks out the window later, after the guy who speeded up has settled back into uniform motion with respect to the non-accelerating ship? He won't know if his ship slowed down, or the other ship speeded up, or some combination of both while he was sleeping. Assuming both ships started at the same place, at the same time, he won't know who has now travelled further (i.e., who has gone faster). He won't know who is younger. But everyone else does. His lack of knowledge about the facts does not change the facts. Knowledge of the recent accelerative history gives you those facts. Igorance of them does not make them non-existent.
Of course the main point to all of this is fairly simple to grasp, and I have stated it repeatedly.
1. One can easily, for mathematical purposes, treat either of two objects in relative motion as being "at rest" (but NOT simultaneously, which you deny).
2. One can go further and, as a philosophical matter, assert that, because they are "equally valid" mathematically, they are therefore "equally valid" ontologically speaking.
3. But no true scientist (as opposed to a true mathematician) would ever claim that any two given frames are "equally valid" as an ontological matter. As I have said before, their are a multitude of strong, empirically-based theoretical reasons for concluding that the earth is revolving around the sun, not vice versa; that the accelerated spaceship is the moving object, as between the two; and that a car is the one really moving with respect to the earth's surface.
4. SR, by it's own theoretical formulas and premises, gives you an empirical basis of detecting which of two relatively-moving objects has been "really" moving (or at least moving faster): simply see which clock recorded less time during the period of relative motion.
5. The mere philosophical assertion that "all reference frames are equally valid" does not, as Einstein hoped, make all motion (including accelerated motion) "truly relative." It is my understanding that most physicists, while they accept GR as a valid, if imperfect, theory of gravity, reject it as a valid theory of "relative motion."
I sent the PM to colton, awaiting the response.
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