New understanding of relativity - twin paradox resolved.

This seems superfluous.

I was told that there was no paradox because only one twin experienced acceleration. This "experience" is absolute not relative (because it is detected non- visually) and therefore negates the symmetry of the twins situations.

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Re: New understanding of relativity - twin paradox resolved.

DrewDad wrote:

LSU professor resolves Einstein's twin paradox

Quote:
"I solved the paradox by incorporating a new principle within the relativity framework that defines motion not in relation to individual objects, such as the two twins with respect to each other, but in relation to distant stars," said Kak.

He also defined motion with probabilistic relationships. This sounds very 'quantum' to me. Maybe this will be a linking mechanism between QED and Relativity. If so, it would be BIG.

The article isn't specific enough. We need more detail.

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bm

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fresco wrote:

This seems superfluous.

I was told that there was no paradox because only one twin experienced acceleration. This "experience" is absolute not relative (because it is detected non- visually) and therefore negates the symmetry of the twins situations.

You're right. Not to disparage the thread, but the twin paradox is not actually a paradox, but is simply a well understood part of a well understood theory.

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The Twin Paradox in more detail

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rosborne,

Very interesting thanks.

In as much that QM dances gladly with "the mysterious" it is not surprising that it may be involved with this one. The concept of "experience" as per "acceleration" clearly leaves itself open to nondualist considerations of observer-observed.

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Actually, whatchya got here is prime example of a so-called science reporter having no idea whereof he speaks - or in this case, types. To begin with, the "Twins Paradox" is an apparent paradox, not a real paradox; without getting all quantum on ya, the central error predicate to this misdirected bit of ignorant media hype is the assumption of an independent-of-observed phenomena fixed inertial frame of reference with respect to both the "stay at home" earth-bound twin and the in-reference-to-the-"stay at home" accellerating spaceborne twin, an assumption invalid in that it violates the Heisenberg Uncertainty Principal (essentially, as the precision of determination either of absolute location or of absolute velocity increases, the precision of determination of the other decreases in direct proportion). The author of the cited "breakthrough paper" article makes no claim of breakthrough, as the article contends, but rather employs applied physics (as opposed to theoretical physics), therewith demonstrating one more illustration (there exist many such - Here is is one, and here Another - (special note: the latter linked webpage will not display in IE; viewing it requires the Firefox browser with MathML Fonts installed) of why there really is no paradox.

Without even going into the cited paper itself, a simple - but actual - reading of the Abstract -

Quote:

Moving Observers in an Isotropic Universe

Journal International Journal of Theoretical Physics
Publisher Springer Netherlands
ISSN 0020-7748 (Print) 1572-9575 (Online)
Subject Mathematics and Statistics and Physics and Astronomy
Status Online first
DOI 10.1007/s10773-006-9281-2
SpringerLink Date Wednesday, January 17, 2007

Subhash Kak

(1) Department of Electrical & Computer Engineering, Louisiana State University, Baton Rouge, LA 70803-5901, USA

Received: 14 August 2006 Accepted: 26 September 2006 Published online: 17 January 2007

Abstract: This paper considers how the motion of an observer in an isotropic universe may be determined by measurements. This provides a means to identify inertial frames, yielding a simple resolution to the twins paradox of relativity theory in such a universe. We propose that isotropy is a requirement for a frame to be inertial; this makes it possible to relate motion to the large scale structure of the universe.

Keywords: inertial frames - special relativity - twins paradox - isotropic universe

reveals the breathless though brainless article's author hasn't done the necessary homework required to complete the assignment.

A textbook explanation of why there is no real paradox may be found Here (note: 72 page .pdf download) Chapter 10 - Relativity (Kinematics) - See in specific: Problem 19, "Modified twin paradox", p. 49 lower and the solution p. 65 upper - Morin, D., in Georgi, H. (2004); Mechanics and Special Relativity - "Newtonian mechanics and special relativity for students with good preparation in physics and mathematics at the level of the advanced placement curriculum. Topics include an introduction to Lagrangian mechanics, Noether's theorem, special relativity, collisions and scattering, rotational motion, angular momentum, torque, the moment of inertia tensor, oscillators damped and driven, gravitation, planetary motion, and an introduction to cosmology."

Sidebar - see also: Harvard Crimson - Chemistry and Physics - Lock Yourself in a Room

Short version of timber's critique of the cited article: Nothing to see there - move along.

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I'm glad others jumped on this bit of sensationalism first. Agreed its poor reporting of science.

You can't study relativity without understanding frames of reference. These kinds of paradoxes nearly always stem from someone thinking old-school in an absolutle frame of reference - which is my frame, centred on me, this is strange because ...

If you propose a thought experiment in a frame of inertia, you'd better consider where most mass and energy lie and not just two or three points of reference in the situation.

Well commented on folks!

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Re: New understanding of relativity - twin paradox resolved.

DrewDad wrote:

Quote:
"I solved the paradox by incorporating a new principle within the relativity framework that defines motion not in relation to individual objects, such as the two twins with respect to each other, but in relation to distant stars," said Kak.

I wasn't aware there was any twin paradox to solve. Time passes slowly for the travelling twin because his spaceship is accelerated; time passes quickly for the twin on Earth because his motion is more or less constant.

While it is somewhat hard to understand why time should pass slowlier when you're being accelerated, it's a straightforward, logical conclusion from the general theory of relativity. The frame of reference has nothing to do with it. Mr. Kak had no paradox to resolve.

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I was not aware of any paradox either! Then again I'm no expert in these things, however:

Time does not pass more slowly for the travelling twin because his spaceship is accelerated, time appears to pass more slowly relative to the non-travelling twin when the travelling twin approaches the speed of light.

Time passes at exactly the same apparent on-board rate from the travelling twin's perspective.

Rate of acceleration is not necessarily overly meaningful to time dilation per se, and although the time dilation effect does take place at lower speeds, it's not too noticeable until approaching the speed of light.

At least that the way I understand it.

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Chumly wrote:

Time does not pass more slowly for the travelling twin because his spaceship is accelerated, time appears to pass more slowly relative to the non-travelling twin when the travelling twin approaches the speed of light.

If that was the whole story, you would have a paradox: To the twin on Earth (TOE), the time of the traveling twin (TT) passes more slowly because TT travels near the speed of light. That's what the special theory of relativity yields, or more specifically, the Lorentz transformation. But TT can apply the Lorentz transformation to TOE's motion just as well, and he can use his own frame of reference to do it. Consequently, TT sees TOE's time pass more slowly than his. After all, Earth is travelling near the speed of light from TT's perspective, and TOE is travelling at the same speed right on it. So as far as motion alone is concerned, the twins' views of each others are completely symmetrical: TT sees TOE's clock run slower than his; TOE sees TT's clock run slower than his; each twin sees the other's clock slowing by exactly the same factor.

But if their views are symmetrical, how come TOE is older than TT when TT returns to Earth? From the viewpoint of special relativity, you have a paradox there. To resolve the paradox you have to consider that TOE lives in a (more or less) inertial system -- he is moving at constant speed -- while TT lives in an accelerted system, so feels forces TOE doesn't feel as a result. Plug that into the general theory of gravity, and it will tell you that TT's clock will be running slower overall.

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What about this where you said:

Thomas wrote:

Time passes slowly for the travelling twin because his spaceship is accelerated.......

And I said:

Chumly wrote:

Rate of acceleration is not necessarily overly meaningful to time dilation per se, and although the time dilation effect does take place at lower speeds, it's not too noticeable until approaching the speed of light.

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What do you mean, "lower speeds"? From TT's point of view, his own speed is zero. It couldn't get lower than that. Speed per se is relative and has nothing to do with it. The relevant difference is that TT feels a force that TOE doesn't feel. That's why TT arrives at the Earth younger than TOE.

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Chumly, it occurs to me that I may not understand your view of the problem. So here's a question to help me see your point of view: In your opinion, how does the traveller explain that he is younger than his twin who stayed on Earth?

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While one of the twins is outward bound, each sees the other's clock slowed down, and each is equally correct, but when the twin in space turns around to come back, he is accelerated and no longer in an inertial reference frame.

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Brandon9000 wrote:

While one of the twins is outward bound, each sees the other's clock slowed down, and each is equally correct, but when the twin in space turns around to come back, he is accelerated and no longer in an inertial reference frame.

I agree with you, Brandon, but Chumly seems to disagree with us. That's why I asked him how in his view the traveller would explain his young age.

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By lower speeds I mean (let's say 100 MPH); the relativistic effects at that point are negligible, no? So how can it be that "because his spaceship is accelerated......." per se is a function of relativistic effects?

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Chumly wrote:

By lower speeds I mean (let's say 100 MPH); the relativistic effects at that point are negligible, no? So how can it be that "because his spaceship is accelerated......." per se is a function of relativistic effects?

Let's say that twin A goes on a trip and comes back to be reunited with twin B. Why do both twins discover that B has aged more than A? Since "travelling at a high speed" is relative, and the twin who remains at home could be equally accused of "travelling at a high speed," what is it that determines which twin will ultimately be obesrved to have aged less, and which to have aged more?

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Can both twins discover that B has aged more than A if the speed differential is only 100 MPH?

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New understanding of relativity - twin paradox resolved.

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