The Twin Paradox Made Simple

[Moronium]

 

 

The validity of SR (or any other physical model for that matter) is entirely unaffected by the validities of the solipsism/materialism philosophies. 

 

Think again (not that it will help).  Every theory at least implicitly adopts some (philosophical) ontology.

 

 SR certainly doesn't require that they do so. What a silly thing to attempt to claim.

 

In addition to contradicting your own prior claims, you display your fundamental misunderstanding of SR.  Ever perform a lorentz transformation?  What value did you insert for "v" in the primary (non-prime, observer's) frame?

[A-wal]

The validity of SR (or any other physical model for that matter) is entirely unaffected by the validities of the solipsism/materialism philosophies. 

 

Think again (not that it will help).  Every theory at least implicitly adopts some (philosophical) ontology.

The only philosophical ontology that's needed to discus the validity of a physical model is that reality is self-consistent. The objective vs subjective nature of reality is entirely separate from the adoption of a self-consistent universe. In a universe in which the speed of light moves at the same rate relative to inertial observers that are in motion relative to each other there can be no preferred frame.

 

And also...

A trained astronaut or any other observer can only be in motion relative to any other object, including the moon. To claim that the astronaut is in motion while the moon is motionless is to claim that the moon is at absolute rest and that either the astronaut's motion is relative to the moon's frame regardless of the astronaut's destination or that the absolute rest frame of the universe somehow depends on the astronaut's choice of destination. You need to think about what the implications would be of the claims you're making and how absurd they actually are.

 

SR certainly doesn't require that they do so. What a silly thing to attempt to claim.

 

In addition to contradicting your own prior claims, you display your fundamental misunderstanding of SR.  Ever perform a lorentz transformation?  What value did you insert for "v" in the primary (non-prime, observer's) frame?

I have never claimed that any frame is preferred over another, I've been very clear that all frames are equally valid.

 

No I've never performed a Lorentz transformation, and I don't ever plan to. Anyone can be taught to do that without having the slightest clue why that gives them the right answer, that's not understanding. It's enough for me to understand that in order for observers that are in motion relative to each other to measure light moving at the same speed relative to themselves they must each be length contracted and time dilated from the perspective of the other and that if either one were to move into the frame of reference of the other that observer will have experienced less proper time than the other because that's the only logically self-consistent way it can possibly work without altering the speed of light between frames.

 

You do know that Lorentz transformations are frame independent right? As in they work both ways?

 

 

And yes, the vast majority of people who say they understand SR, and act as its staunchest defenders, really do not understand it at all, as you have already seen.

:) You mean like Exchemist thinking that time dilation and length contraction cancel each other out...

What people often seem to overlook is that the time dilation seen by observers in relative motion is balanced by length contraction, such that c can be the same for both observers, their relative motion notwithstanding.

...or you who thought that two objects couldn't move at a velocity greater than c relative to each other from the perspective of a third observer that was in a frame inbetween theirs. Check this out if you want to see what a wiki parrot pretending to understand SR looks like when they're called out: http://www.scienceforums.com/topic/29501-the-underlying-problem-with-some-science-is-interpretation/page-10 It's hilarious.

 

You two are far worse than Moronium. At least he's arguing from a position of what he sees as understanding, not just hopping on the bandwaggon of what he sees as a safe bet based on faith in what an institution endorses rather than any level of actual understanding of the model. That's disgusting.

Edited May 4, 2018 by A-wal

[Moronium]

when I posted that graphic I didn't make any claim that it is "True". I posted it as an example (a good one, I think) of what SR claims about relative motion and reciprocal time dilation.

 

 

OK. I agree that it is a good example of how some (maybe most) SR advocates might respond.

 

But for reasons I basically summarized in response, I don't think it's a "good" (persuasive, physically meaningful, etc.) response to the issue.  You actually didn't even say why a lorentzian diagram was supposed to explain how and why time dilation could "actually" be true, but I kinda filled that in. 

 

The response of SR is weak.  Weak enough that even Einstein (who had been desperately looking for a valid refutation to the (true) twin paradox) rejected it.   He never found one, although he later tried to use a GR-like explanation, combined with "fictitious gravitation fields" to resolve it.  His "solution" has never met with much acceptance, or been widely adopted, however.

 

John Baez's website had this to say about it:

 

The Equivalence Principle analysis of the twin paradox simply views the scenario from the frame in which Stella is at rest the whole time.  This is not an inertial frame; it's accelerated, so the mathematics is harder.  But it can certainly be done.  When the mathematics is described fully, what results is that we can treat a uniformly accelerated frame as if it were an inertial frame with the addition of a "uniform pseudo gravitational field". 

 

By a "pseudo gravitational field", we mean an apparent field (not a real gravitational field) that acts on all objects proportionately to their mass; by  "uniform" we mean that the force felt by each object is independent of its position.  This is the basic content of the Equivalence Principle.

 

The Equivalence Principle analysis of the twin paradox does not use any real gravity, and so does not use any General Relativity.  (General Relativity is the study of real gravitational fields, not pseudo ones, so it has nothing to say about the twin paradox.)...

 

But remember, this is not an explanation of the twin paradox.  It's simply a description of it in terms of a pseudo gravitational field.  The fact that we can do this results from an analysis of accelerated frames within the context of Special Relativity....the pseudo gravitational field becomes infinitely strong, and so does the time dilation.  So Terence ages years in an instant—physically unrealistic, but so is instantaneous turnaround.

 

 

 

 

http://math.ucr.edu/home/baez/physics/Relativity/SR/TwinParadox/twin_paradox.html

Edited May 4, 2018 by Moronium

[A-wal]

Moronium, perhaps it would help if you could explain why you think that two observers that are in motion relative to each other can't both be right about the other being time dilated and length contracted.

 

It's like two people who are facing each other, to one of them left is north and right is south but to the other right is north and left is south. Both of them are correct. For observers in relative to motion to each other it's left/right, not north/south.

 

If person 1 turns 180 degrees then they have entered the 'frame of reference' of person 2 and they will now use this frame's orientation but if person 2 turns 180 degrees instead then they have entered the 'frame of reference' of person 1 and they will now use that frame's orientation. There's no contradiction.

 

The same thing is true when an object accelerates into the frame of reference of another object, that object will now be in a frame in which they were previously length contracted and time dilated so they will have experienced less proper time. There's no contradiction here either. I honestly can't understand why you take so much issue with this.

[Moronium]

Moronium, perhaps it would help if you could explain why you think that two observers that are in motion relative to each other can't both be right about the other being time dilated and length contracted.

 

It's like two people who are facing each other, to one of them left is north and right is south but to the other right is north and left is south. Both of them are correct. For observers in relative to motion to each other it's left/right, not north/south.

 

 

 

 

I've already explained it about 20 times in about 20 different ways.  It's not "like" your example.  But even in your example, the direction north never changes regardless of how any particular is aligned in relation to north.  "Both" of them can be correct, if that's what you want to call it, but ONLY in a accidental, strictly subjective sense which has NOTHING to do with objective reality.  That's the point.  To hold that "reality" and "truth" reside in idiosyncratic appearance and subjective perception, while denying all possibility of objective truth, is full-blown solipsism.

 

Read Hogg's distinction between "observing" and "seeing," and between "real" and "apparent."  (Post 108)

Edited May 4, 2018 by Moronium

[Moronium]

The ancient greek philosopher, Parmenides, who I have mentioned before somewhere in this forum, held that all motion was mere illusion--in reality, nothing ever moved, he claimed.  Nobody bought it, but he had some very clever arguments which were used to advocate his views and which stymied his listeners.

 

Karl Popper (who I also just mentioned), the famous philosopher, used to converse with Einstein who he called (only-half kiddingly) "Parmenides."

 

And, indeed, taken literally, Einstein can be seen as denying all motion.  After all, SR requires every inertial frame of reference (of which there are an infinite number, theoretically) in existence to be treated as "motionless."  Taken literally, the end result is that nothing ever moves.

Edited May 4, 2018 by Moronium

[A-wal]

You haven't explained it once. You haven't given any kind of actual reason to think that it's not true, you just keep saying that it can't be true, that's it's not objective or that it's solipsism. It makes it very hard to take you seriously.

 

The point I was making us that to two observers facing in opposite directions left and right are reversed but neither one is in any kind of preferred frame. But are right from their own frame of reference.

 

Can you give any substantial reason why two objects that are in motion relative to each other can't both be time dilated and length contracted for the perspective of the other?

 

And, indeed, taken literally, Einstein can be seen as denying all motion.  After all, SR requires every inertial frame of reference (of which there are an infinite number, theoretically) in existence to be treated as "motionless."  Taken literally, then end result is that nothing ever moves.

Either that, or all motion is relative. :)

Edited May 4, 2018 by A-wal

[Moronium]

You haven't explained it once. You haven't given any kind of actual reason to think that it's not true, you just keep saying that it can't be true,  

 

For a muslim fundie no reason could ever be given to explain why the Koran is not the word of God.  About time for you to head to the mosque, throw down your rug, face mecca, get down on all fours, and chant with the boys, aint it?

Edited May 4, 2018 by Moronium

[Moronium]

With respect to how a subject's mental impressions can alter the external world, I asked this question in another thread:

 

Posted 02 May 2018 - 06:32 PM

Let's say there are two posts planted firmly in the ground in a field.  They are not moving with respect to each other, and they will not move under their own volition.

 

I won't even try to say what the distance between them "really" is, because is doesn't even matter.  It could be 1 mile.  It could be 1/2 mile.  It could be 10."  It could be 10 feet.  It doesn't matter in the least for the purposes of this question.

 

Does that distance, whatever ever it is, change if some rocket flies past near the speed of light?  Would that cause  the two posts to move closer together or farther apart from each other, do you think?

 

----------

The answer I got was this:

 

"I am utterly astonished that someone who has seemingly devoted so much time to the subject would ask a question like this. 

 

The answer obviously depends on whether the posts are observed from the rocket or from the ground. There is no single answer to this, any more than there is to the speed of clocks."

 

http://www.scienceforums.com/topic/29314-strange-claims-about-relativistic-time-split-from-a-alternative-theories-thread/page-12

 

--------

 

Obviously this is the type of answer which would come from an abject solipsist.  There is no objective truth whatsoever, and subjective thoughts can presumably "force" posts, which may be light years away, to "move." The distant onlooker accomplishes this telekinetic trick merely by "thinking they move,"  even though someone looking at both of them wouldn't see it.  So they move, and they don't move, all at the same time.  For a solipsist this is "obvious," and it is "utterly astonishing" that anyone could be so stupid as to question it.

 

Believe that if you want.  But before some gullible person falls into that metaphysical quicksand, I would still recommend that they consider Prof. Hogg's admonition that you must distinguish real from apparent effects and "seeing" from "observing."

 

 

Edited May 5, 2018 by Moronium

[Moronium]

As all physicists acknowledge, the LT predict that relativistic changes will occur ONLY in the object which is moving (faster).

 

OK, next question:  Moving with respect to what?

 

SR:.  With respect to the thing that's not moving, that's what.

 

Q.  How do you know what that thing is though?  Does the LT tell you that?

 

SR:  No, the LT doesn't tell you a damn thing about which of two objects is moving--it's just a formula which knows nothing about the world, per se.  You, not the LT, have to determine which object is at rest.

 

Q.  So, then, how do I determine that?  How do I know which object  is "at rest?"

 

SR:  Look in the mirror, fool.  It's always YOU.

 

Q.  But who's "you?"  Me, or the other guy (who also has a mirror)?  

 

SR:.  Both, fool.  Any more stupid questions?

 

Q.  Yeah, a couple maybe....How could they both be at rest and yet still be moving relative to each other?  How does that make any sense?

 

SR:  OK, son, now you've gone plumb over the line!  You're an annoying, stupid twit.  It makes sense because I told you that's the way it is.  It's the TRUTH.  You can't possibly say the TRUTH doesn't make sense.  Only a fool would think that.

 

Q: another question....

 

SR:  No more questions, boy.  Just shut up and listen.  Absorb the truth and become enlightened.

Edited May 5, 2018 by Moronium

[OceanBreeze]

Let there be two objects which start out at the same point in spacetime. Now let them be on divergent paths where one of the particles is on a path in which it is moving inertially at all times, as evidenced by an accelerometer, and the other object travels a path that goes through accelerations, again as evidenced by the indication of an accelerometer carried along with it. If the two paths once again merge or intersect, it will be the object that has undergone acceleration that experiences less passage of time (ages less).

 

This is true regardless of any arbitrary choice of reference frame and so is free of any confusion about which object is at rest and which is moving with respect to whatever.

 

The observation of acceleration does provide an objective way to tell the difference.

 

The problem with this explanation is that it goes outside of the bounds set by SR, as SR does not deal with acceleration! This solution relies on GR and is similar to the solution given by GR for objects in different gravitational potentials undergoing different passage of times. And time dilation under GR is asymmetrical, while under SR it is said to be symmetrical.

 

So, using the argument based on acceleration to solve the twin paradox does not support nor does it falsify the claim of symmetrical time dilation. In fact, it says nothing at all about that.

 

To confirm symmetrical time dilation, we may need to look beyond the twin paradox and find an experiment that uses relativistic doppler effect.

 

Quoting from the source:

 

The relativistic Doppler effect is different from the non-relativistic Doppler effect as the equations include the time dilation effect of special relativity and do not involve the medium of propagation as a reference point. They describe the total difference in observed frequencies and possess the required Lorentz symmetry.

Edited May 5, 2018 by OceanBreeze

[A-wal]

The problem with this explanation is that it goes outside of the bounds set by SR, as SR does not deal with acceleration! This solution relies on GR and is similar to the solution given by GR for objects in different gravitational potentials undergoing different passage of times. And time dilation under GR is asymmetrical, while under SR it is said to be symmetrical.

 

So, using the argument based on acceleration to solve the twin paradox does not support nor does it falsify the claim of symmetrical time dilation. In fact, it says nothing at all about that.

 

To confirm symmetrical time dilation, we may need to look beyond the twin paradox and find an experiment that uses relativistic doppler effect.

 

Quoting from the source:

 

The relativistic Doppler effect is different from the non-relativistic Doppler effect as the equations include the time dilation effect of special relativity and do not involve the medium of propagation as a reference point. They describe the total difference in observed frequencies and possess the required Lorentz symmetry.

This is complete nonsense. SR wouldn't work as a model without including acceleration between frames. GR handles gravitational acceleration by treating it as following a straight line through curved space-time but acceleration from one inertial frame to another is of course included in SR.

 

Nothing in the twin paradox falls outside the framework of SR. GR came ten years later, do you really think that the twin paradox wasn't resolved until GR came along? It was never a genuine paradox, it was to show how the apparent paradox is resolved, using SR.

 

Let there be two objects which start out at the same point in spacetime. Now let them be on divergent paths where one of the particles is on a path in which it is moving inertially at all times, as evidenced by an accelerometer, and the other object travels a path that goes through accelerations, again as evidenced by the indication of an accelerometer carried along with it. If the two paths once again merge or intersect, it will be the object that has undergone acceleration that experiences less passage of time (ages less).

 

This is true regardless of any arbitrary choice of reference frame and so is free of any confusion about which object is at rest and which is moving with respect to whatever.

 

The observation of acceleration does provide an objective way to tell the difference.

This is wrong as well. The difference in age between two observers is not directly caused by acceleration, it's caused by their relative velocity.

 

If an observer accelerates away from another observer and then accelerates back into the other observer's frame again, the one who accelerated will have experienced less proper time but if they wait twice as long on their watch before accelerating back into the other observer's frame the difference in elapsed time would be doubled.

 

Acceleration is just how one observer moves into the frame of reference of another. The one who changes frames is the one who experiences less proper time because they are the one who was time dilated and length contracted from the frame they're in after accelerating back into the original frame.

Edited May 5, 2018 by A-wal

[A-wal]

For a muslim fundie no reason could ever be given to explain why the Koran is not the word of God.  About time for you to head to the mosque, throw down your rug, face mecca, get down on all fours, and chant with the boys, aint it?

SR isn't a faith based model, it's based on the consistency of the speed of light across all inertial frames and is the only way to resolve that consistency considering that objects in different frames are in motion relative to each other but light moves at the same speed relative to themselves for all of them. SR also makes predictions about the difference in elapsed that occurs when object that are in relative motion are brought back into the same frame to compare clocks and those predictions have always proven to be true.

 

With respect to how a subject's mental impressions can alter the external world, I asked this question in another thread:

 

Posted 02 May 2018 - 06:32 PM

Let's say there are two posts planted firmly in the ground in a field.  They are not moving with respect to each other, and they will not move under their own volition.

 

I won't even try to say what the distance between them "really" is, because is doesn't even matter.  It could be 1 mile.  It could be 1/2 mile.  It could be 10."  It could be 10 feet.  It doesn't matter in the least for the purposes of this question.

 

Does that distance, whatever ever it is, change if some rocket flies past near the speed of light?  Would that cause  the two posts to move closer together or farther apart from each other, do you think?

 

----------

The answer I got was this:

 

"I am utterly astonished that someone who has seemingly devoted so much time to the subject would ask a question like this. 

 

The answer obviously depends on whether the posts are observed from the rocket or from the ground. There is no single answer to this, any more than there is to the speed of clocks."

 

http://www.scienceforums.com/topic/29314-strange-claims-about-relativistic-time-split-from-a-alternative-theories-thread/page-12

 

--------

 

Obviously this is the type of answer which would come from an abject solipsist.  There is no objective truth whatsoever, and subjective thoughts can presumably "force" posts, which may be light years away, to "move." The distant onlooker accomplishes this telekinetic trick merely by "thinking they move,"  even though someone looking at both of them wouldn't see it.  So they move, and they don't move, all at the same time.  For a solipsist this is "obvious," and it is "utterly astonishing" that anyone could be so stupid as to question it.

 

Believe that if you want.  But before some gullible person falls into that metaphysical quicksand, I would still recommend that they consider Prof. Hogg's admonition that you must distinguish real from apparent effects and "seeing" from "observing."

It still has absolutely nothing at all to do with solipsism and you're still making a complete idiot of yourself by trying to claim that it does.

 

Of course the distance between the posts is unaffected by a rocket flying past them, it's simply a different distance for an observer in the rocket who's in motion relative to the posts than it is for an observer on the ground who's at rest relative to the posts. The distance between objects doesn't change for an observer if another object is motion to them, that's not how time dilation and length contraction work. It's just that objects that are in motion relative to each don't agree about the distance of lengths in time and space, if they did then the speed of light couldn't possibly be the same for observers in motion relative to each other.

 

As all physicists acknowledge, the LT predict that relativistic changes will occur ONLY in the object which is moving (faster).

 

OK, next question:  Moving with respect to what?

 

SR:.  With respect to the thing that's not moving, that's what.

 

Q.  How do you know what that thing is though?  Does the LT tell you that?

 

SR:  No, the LT doesn't tell you a damn thing about which of two objects is moving--it's just a formula which knows nothing about the world, per se.  You, not the LT, have to determine which object is at rest.

 

Q.  So, then, how do I determine that?  How do I know which object  is "at rest?"

 

SR:  Look in the mirror, fool.  It's always YOU.

 

Q.  But who's "you?"  Me, or the other guy (who also has a mirror)?  

 

SR:.  Both, fool.  Any more stupid questions?

 

Q.  Yeah, a couple maybe....How could they both be at rest and yet still be moving relative to each other?  How does that make any sense?

 

SR:  OK, son, now you've gone plumb over the line!  You're an annoying, stupid twit.  It makes sense because I told you that's the way it is.  It's the TRUTH.  You can't possibly say the TRUTH doesn't make sense.  Only a fool would think that.

 

Q: another question....

 

SR:  No more questions, boy.  Just shut up and listen.  Absorb the truth and become enlightened.

Dullard: As all physicists acknowledge, the LT predict that relativistic changes will occur ONLY in the object which is moving (faster).

 

Actual SR: Neither object is moving faster because neither object has independent motion, they're in motion relative to each other and each will be time dilated and length contracted from the other's frame of reference.

 

 

Dullard: OK, next question: Moving with respect to what?

 

Misrepresented SR: With respect to the thing that's not moving, that's what.

 

Actual SR: To each other.

 

 

Dullard: How do you know what that thing is though?  Does the LT tell you that?

 

Misrepresented SR: No, the LT doesn't tell you a damn thing about which of two objects is moving--it's just a formula which knows nothing about the world, per se.  You, not the LT, have to determine which object is at rest.

 

Actual SR: It makes absolutely no difference which frame of reference is used. If you want to know what an observer experiences then you need to work out the time dilation and length contraction that are applied to objects that are in motion relative to that observer.

 

 

Dullard: So, then, how do I determine that?  How do I know which object  is "at rest?"

 

Misrepresented SR: Look in the mirror, fool.  It's always YOU.

 

Actual SR: If they're at rest then they are at rest relative to each other so there is no time dilation or length contraction. If they're in motion relative to each other then each is time dilated and length contracted, that's how light can move at the same velocity for both of them relative to themselves despite their motion relative to each other.

 

 

Dullard: But who's "you?"  Me, or the other guy (who also has a mirror)?  

 

Misrepresented SR:.  Both, fool.  Any more stupid questions?

 

Actual SR: The situation is exactly the same from their perspective if neither of you are under acceleration. Objects that are in motion relative to them (including you) are time dilated and length contracted, that's still how light can move at the same velocity for both of them relative to themselves despite their motion relative to each other. You are time dilated and length contracted from the frame by the exact same amount as they are time dilated and length contracted from your frame.

 

 

Dullard: Yeah, a couple maybe....How could they both be at rest and yet still be moving relative to each other?  How does that make any sense?

 

Misrepresented SR: OK, son, now you've gone plumb over the line!  You're an annoying, stupid twit.  It makes sense because I told you that's the way it is.  It's the TRUTH.  You can't possibly say the TRUTH doesn't make sense.  Only a fool would think that.

 

Actual SR: They're not. They are either at rest relative to each other or in motion relative to each other, never both. Pay attention.

 

 

Dullard: another question....

 

Misrepresented SR: No more questions, boy.  Just shut up and listen.  Absorb the truth and become enlightened.

 

Actual SR: Is it as dumb as the others?

Edited May 5, 2018 by A-wal

[OceanBreeze]

This is complete nonsense. SR wouldn't work as a model without including acceleration between frames. GR handles gravitational acceleration by treating it as following a straight line through curved space-time but acceleration from one inertial frame to another is of course included in SR.

 

Nothing in the twin paradox falls outside the framework of SR. GR came ten years later, do you really think that the twin paradox wasn't resolved until GR came along? It was never a genuine paradox, it was to show how the apparent paradox is resolved, using SR.

 

 

 

 

 

Yes, I should have said that acceleration becomes much more complex within SR.

 

"Accelerations in special relativity (SR) follow, as in Newtonian Mechanics, by differentiation of velocity with respect to time. Because of the Lorentz transformation and time dilation, the concepts of time and distance become more complex, which also leads to more complex definitions of "acceleration". SR as the theory of flat Minkowski spacetime remains valid in the presence of accelerations, because general relativity (GR) is only required when there is curvature of spacetime caused by the energy-momentum tensor (which is mainly determined by mass). However, since the amount of spacetime curvature is not particularly high on Earth or its vicinity, SR remains valid for most practical purposes, such as experiments in particle accelerators"

 

 

 

 

This is wrong as well. The difference in age between two observers is not directly caused by acceleration, it's caused by their relative velocity.

 

If an observer accelerates away from another observer and then accelerates back into the other observer's frame again, the one who accelerated will have experienced less proper time but if they wait twice as long on their watch before accelerating back into the other observer's frame the difference in elapsed time would be doubled.

 

Acceleration is just how one observer moves into the frame of reference of another. The one who changes frames is the one who experiences less proper time because they are the one who was time dilated and length contracted from the frame they're in after accelerating back into the original frame.

 

 

 

There is no way to switch from one inertial frame to another without invoking acceleration! So, it is just a semantical device to say the difference in age is not caused by acceleration but it is caused by switching between inertial frames!

 

As long as there is acceleration involved, the solution to the twin paradox is similar to the solution given by GR for objects in different gravitational potentials undergoing different passage of times. And time dilation under GR is asymmetrical, just as the solution to the twin paradox is asymmetrical.

 

Once again, using the argument based on acceleration (or switching between inertial frames) to solve the twin paradox does not support the claim of symmetrical time dilation.

 

To confirm symmetrical time dilation, we may need to look beyond the twin paradox and find an experiment that uses relativistic doppler effect.

 

Such an experiment has been discussed in several places but as far as I know, has never been done.

 

Thus, symmetrical time dilation remains a claim of SR that may well be true, but never tested so never confirmed or falsified.

[Moronium]

To confirm symmetrical time dilation, we may need to look beyond the twin paradox and find an experiment that uses relativistic doppler effect.

 

 

 

The Doppler effect is merely apparent, and not real, according to Prof. Hogg.  As such, it in no way influences or affects actual time dilation.  This is mainstream physics.  The author you cite apparently is not.

 

.  

A common confusion for students of special relativity is between that which is real and that which is apparent. For instance, length contraction is often mistakenly thought to be some optical illusion. But moving things do not “appear” shortened, they actually are shortened. How they appear depends on the particulars of the observation, including distance to the observer, viewing angles, times, etc. The observer finds that they are shortened only after correcting for these non-fundamental details of the observational procedure. I attempt to emphasize this distinction: All apparent effects, including the Doppler Shift, stellar aberration, and superluminal motion, are relegated to Chapter 7.

 

 

http://cosmo.nyu.edu/hogg/sr/sr.pdf

 

Thus, symmetrical time dilation remains a claim of SR that may well be true, but never tested so never confirmed or falsified.

 

 

 

Hafele and Keating board a plane in London and fly to New York.  As they are in flight, they are looking at their atomic clock.  Based on the assumption that, due to the velocity effect, their (NOT THE EARTH CLOCK) has slowed down, they make predictions about what the earth clock it was synchronized with is then reading. They periodically confirm (via radio signals) the accumulating difference with a earth observer as they go.  Their (confirmed) findings, as they go, show that the earth clock is running FASTER (not slower) than their clock.

 

In short, they are not "seeing" that time dilation is reciprocal and they are assuming that it is completely false.  When they land and compare clocks,  Their predictions are correct.  This proves time dilation is NOT reciprocal.

 

Who knew? I woulda thought for sure that each clock would be slower than the other, ya know?  

Edited May 5, 2018 by Moronium

[sluggo]

#86

Now, apriori, you know two things will be true, when you finally bring them back together.
A.  Each clock will show ONLY one time, 9:00 A.M. EST, March 10, 2020, for example.
B.  Whatever the two readings are, whatever you can conceive of them to be, both clocks will NOT display a time which is earlier than the other one does.  Only one can possibly be "earlier," even if both somehow went backwards in time.
Ergo, there is, and can be, no "reciprocal time dilation."

 

--
Wrong! It will depend on the total speed profile of each.  There is no need of a special  setup. Duplicate accurate clocks will accumulate the varying time for each, which is visible at a comparison in a common location. The probability of both following identical profiles is extremely small, so in general one will show more lost time than the other.

All clocks move and therefore lose time at different degrees. Only the difference is measured.

The drawing is a simple 'twin' scenario, without the complications of acceleration. Constant light speed profile is blue. A and B leave U at constant speed. After separating a distance m from A, B returns to A at distance x1. The additional distance n that B travels is reflected in the opposite direction to show the total distance traveled by B as x2. Assume both clocks run at the same rate. The B clock reading the same as the A clock reading is a contradiction since the B clock would have to move faster than A for some portion of the trip, and in doing so, would have experienced more time dilation.

 

[Moronium]

Let me guess, Sluggo.  In your diagram the vertical line marked "t" is for time.

 

One assumption underlying your graph is that a person who is not moving is "travelling through time at c."

 

The assumption has NOTHING to do with physical reality.

 

For one thing  no such thing as "time" exists in the external world.  It is strictly an abstract mental concept.

 

For another, even as a strictly conceptual matter, it makes no sense to talk about a "path" through time.  Time is not a spatial concept.  You can take a "path" through the woods, but you can't take a path through time. Let alone at the speed of light!

 

Is there anything about your post which you think "proves" that time dilation is reciprocal?  Doesn't sound like it, eh?  You say:

 

The B clock reading the same as the A clock reading is a contradiction...

 

If time dilation was the same for each clock, then, when reunited, they might at least read the same (rather than each being slower than the other).  They don't.

Edited May 6, 2018 by Moronium