Is asymmetric time dilation in twin paradox possible in SR?

ghwellsjr

Yes, even with sound when the traveler reverses direction, he observes an increase in the pitch of the sound coming from a remote stationary source. However, the Doppler factors for going and coming are not reciprocals like they are for light and that is what makes the difference. You really should read up on your subject matter before you present these false notions.
The Twin Paradox was introduced by Einstein in his first paper on Special Relativity in 1905 at the end of section 4. It involved a continuously accelerating clock traveling in a circle and reuniting with a stationary clock and running slower than the stationary clock. Einstein didn't call this a paradox (because it isn't) but he did show the asymmetrical time dilation right from the very beginning of his theory. It wasn't something added later.
You should find that hard to digest because it isn't true. Where'd you get such a strange notion from?

The rest of your thread shows a complete lack of regard for all the help you have been given by so many people on this thread. All your questions have been previously answered. Go back and read what has already been offered to you instead of just repeating your unsubstantiated claims.
This was answered previously in my reference to Einstein's paper. Yes, of course we can understand the twin paradox with SR (that's where it was introduced) but you can also get an explanation from GR if you want.

ImaLooser

Physicist Max Born, a colleague and good friend of Albert Einstein, wrote that “the clock paradox is due to a false application of the special theory of relativity.” Wolfgang Pauli says of the paradox in his brilliant (according to Albert E.) 1921 treatise on relativity, “Of course, a complete explanation of the problem can only be given within the framework of the general theory of relativity.”


The issue is discussed in detail here http://mathpages.com/rr/s4-07/4-07.htm

ghwellsjr

But if you read to the end of the relevant paragraph, you will see:
As I said, you can use GR to explain the twin paradox but if we assume the absence of gravity, you can do it just with SR as Einstein did in his 1905 paper.

harrylin

Good - but it should (or at least could!) have been sufficient to bring this to an end. Everything that followed in your post was already answered several times by several people including myself, and with references again in this thread.
Yes indeed! I now unsubscribe from both these twin paradox spin-off threads.

arindamsinha

Oh, let me acknowledge that the responses have been very helpful, guys. It has clarified a number of things on how the SR theory is interpreted and applied. Perhaps at the cost of repetition and disagreements, I have been able to get some very good insights.

ghwellsjr

Good, now do you see that the answer to your question is "yes" and no more questions need to be asked on this thread?

arindamsinha

Yes, I think all the responses were very helpful.

DaleSpam

This is not correct. Those words are simply an English translation of some of Einstein's early writings. They do not limit the modern definition of the two postulates. In physics the early pioneers are respected, but not worshipped, and their words are not considered some sort of final gospel, never to be modified in any way.

The modern definition of SR, the two postulates, is very much focused on the concept of an inertial frame, despite the fact that it was not explicitly mentioned by Einstein. See any college lecture notes or textbook on SR, e.g. http://www.phys.ufl.edu/~acosta/phy2...elativity2.pdf

OK. This seems to destroy your own argument since you appear to realize that, now that the modern definitions of inertial frames have been introduced, they have resolved any SR paradoxes and explained the observations.

No. This is not correct. Please update your definitions, they are 107 years old now.

PAllen

Also, it helps to read complete paragraphs, rather than snippets out of context. While not using the same terminology as modern writers, there is no doubt of Einstein's intent when the context is given. For example, the following is the more complete text around use of "uniform translatory mortion":

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In order to attain the greatest possible clearness, let us return to our example of the railway carriage supposed to be travelling uniformly. We call its motion a uniform translation ("uniform" because it is of constant velocity and direction, " translation " because although the carriage changes its position relative to the embankment yet it does not rotate in so doing). Let us imagine a raven flying through the air in such a manner that its motion, as observed from the embankment, is uniform and in a straight line. If we were to observe the flying raven from the moving railway carriage. we should find that the motion of the raven would be one of different velocity and direction, but that it would still be uniform and in a straight line. Expressed in an abstract manner we may say : If a mass m is moving uniformly in a straight line with respect to a co-ordinate system K, then it will also be moving uniformly and in a straight line relative to a second co-ordinate system K1 provided that the latter is executing a uniform translatory motion with respect to K. In accordance with the discussion contained in the preceding section, it follows that:

If K is a Galileian co-ordinate system. then every other co-ordinate system K' is a Galileian one, when, in relation to K, it is in a condition of uniform motion of translation. Relative to K1 the mechanical laws of Galilei-Newton hold good exactly as they do with respect to K.
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Note especially that last part. This shows, with absolute clarity, that Einstein was referring to inertial frames.

ImaLooser

The author, Kevin S. Brown, is recognizing contrary arguments with which he does not agree.

PAllen

He also admits there is 'spirited debate on this', and does not claim his view is universally accepted or even the majority view. While he has some eminent scientists sharing his view (Einstein in some writing - but not in 1905; Max Born; Pauli in 1921, but not later), he does not present more recent scientific views. The 'only SR is need to explain the twin paradox' view is pretty clearly the majority view of modern scientists. However, a lot boils down to what it means to 'explain'. SR and Galilean relativity take as an axiom there is some family of inertial frames which can be experimentally identified. An explanation of this fact is outside their purview, because it is an axiom (supported by thousands of years of observation).

Mach took as an axiom that there had to be some explanation of inertia. GR only partially, at best, explains inertia. The upshot, in my view, is that GR adds very little to the understanding because it fails to really explain inertia. It also completely fails to explain the origin of the absolute character of rotation.

[Edit: Let me explain how GR completely fails to explain inertia in any fundamental way. A spacetime that is asymptotically flat with a single rocket that can control its thrust is a solution of the EFE. This solution will be nothing but SR to any observable precision. The rocket, despite no other matter in the universe, will find that if it fires its thrust, an accelerometer inside the cabin measures acceleration; if thrust is turned off, it does not. This is exactly the state of affairs in SR and in Newtonian physics. GR has, in this trivial universe, added exactly nothing to the understanding of inertia. One thing this example does show, is that outside of mathematical abstractions, there is a clear physical distinction to non-inertial frames. You have to do something like fire a rocket, or have an electric field and be charged, etc. to undergo non-inertial motion. Ultimately, IMO, inertia remains as much a mystery now as in Newton's time. GR unified gravity and inertia, but despite Einstein's hopes, did not make any real progress explaining inertia.]

arindamsinha

To All - the additional comments and responses are very helpful. Thanks.

This is actually most interesting, and I have thought about it quite a lot. It seems an area where relativity theory seems to still have a gap - it may be consistent and predictive, but does not explain the physical principle behind one of the basic concepts it uses - the 'inertia' behind the inertial frame.

Is anyone aware of any really good and credible alternative theories about the origin of inertia?

DaleSpam

I agree here. I think that GR uses inertia to explain gravitation, but does not explain inertia.

DaleSpam

What you are asking for is impossible. Inertia is part of the postulates of relativity. It is not possible for any theory to explain it's own postulates. All it can do is use its postulates to explain other phenomena. All we can ask of any theory is for it to be "consistent and predictive".

arindamsinha

All I asked was whether there was some other credible theory that does explain inertia. I don't think that is asking for the impossible.

Is it so wrong to even be inquisitive about the reason behind a 'postulate' of a great theory?

DaleSpam

I wasn't objecting to that part of your post. It is perfectly fine to look for more fundamental theories in which the postulates of less fundamental theories can be explained. However, the more fundamental theory will also have postulates that are not explained, even if it is a complete theory of everything. So having unexplained postulates does not constitute a gap in a theory and the only standard to judge theories is their being consistent and predictive. That is why I was objecting to the quoted part of your post.