Paradoxes and Dilemmas

tvanflandern
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21 years 10 months ago #4477 by tvanflandern

Replied by tvanflandern on topic Reply from Tom Van Flandern

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>where can you find the paper?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Meta Research Bulletin, vol. 11, #3, Sept. 15, pp. 39-46 (2002). By journal policy, it won't be available on-line for a minimum of two years. If your nearest technical library doesn't subscribe, ask them to. Or spring for a 4-issue subscription of your own, a bargain at $15.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>In this idea are you saying time is asymetrical.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Time in the *theory* of special relativity (SR) is different at every point in different reference frames. It is well-known that, according to SR, there is no "universal instant of now". Even though all clocks in each of two frames are synchronized within their own frame, multiple clocks cannot be synchronized across frames because of "time slippage", which is a larger effect than "clock slowing" due to relative speed. -|Tom|-

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tvanflandern
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21 years 10 months ago #3861 by tvanflandern

Replied by tvanflandern on topic Reply from Tom Van Flandern

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>The space travelers clock IS slowing but the space traveler won't know this because they have nothing to compare it to.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

They could carry along a rate-adjusted Earth-frame clock, for example. Or they could just observe Earth clocks and see that their own clocks were ticking faster.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>If they tried to compare it against earths time then they are peering into a different frame which makes it *appear* as if time there has slowed when in reallity what has happened is the space traveler has accelerated.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Now there is absolutely no need of that. The spacecraft could have been coming from infinity and just passing Earth when the spacecraft twin was born. Accelerations are never a required part of the twins paradox -- a fortunate circumstance because accelerations do not affect clocks or aging.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>if you were to adjust the earth clock appropriately for the speed differential of the space traveler there would be no paradox. Time is relative to speed.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

This is how Lorentzian relativity deals with the twins. But in SR, each twin sees the clocks and aging of the other proceeding more slowly than his own.

In SR, taking along an adjusted Earth clock changes nothing physically. But it does help see how SR really works, which is why I did that in the article I cited.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>Again, I'm not in disagreement with the idea of slowing time. I am in disagreement with the twin paradox using 4 clocks then comparing 2 of them which reside in differnt frames.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

In SR, it is very difficult to make any such comparison because of the lack of distant simultaneity. So both the past and the future are involved in any such comparison, using the rules of SR.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>It seems to me that gravity is exactly twice speed.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

That is because, for a circular orbit, v^2 = potential, so twice the percentage change in velocity equals the percentage change in potential.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>Is c^2 actually the speed of gravity?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

c^2 cannot be the speed of anything because it does not have dimensions of length over time; i.e., it is not a distance traveled in some time interval. Note that the numerical value associated with c^2 can be larger than, equal to, or smaller than the numerical value associated with c just depending on the units chosen. For example, we commonly use c = 1 in physics. -|Tom|-

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tvanflandern
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21 years 10 months ago #4353 by tvanflandern

Replied by tvanflandern on topic Reply from Tom Van Flandern

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>I declare the paradox alive and well in the context of SR.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Read the article. It was written carefully, is intelligible, and has passed peer review. And it resolves the SR paradox.

Although I sympathize with the desire to ask more questions, ultimately they are all addressed in the article, and anything I might say here (I've already said too much) simply leads to more questions also answered in the article. I am trying to avoid retyping the article in its entirety here. (I coudn't easily manage the Lorentz transformations or the figure here anyway.)

Bottom line: If you care about my opinion of the resolution, read the article.

I draw your attention to the point that MRB subscribers who have read the article are apparently not among those still asking questions here. -|Tom|-

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Larry Burford
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21 years 10 months ago #3863 by Larry Burford

Replied by Larry Burford on topic Reply from Larry Burford

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>
<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>
Does that mean that at a GPS clock vicinity, a person ages at a 38,700 ns/day slower rate than a person on earth?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Yes. All his electrons orbit faster at that rate. -|Tom|-
[amended 2002/12/18 -- "faster" because of weaker gravitational potential]
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Dr Van Flandern, don't you mean -

No. All his electrons orbit faster ... because of weaker gravitational potential

?

In this example the clock slowing caused by higher speed is not enough to counteract the clock speeding caused by higher altitude (lower potential), so someone near and moving with a GPS satellinte will age 38,700 nSec/day faster than someone on the ground.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>
Read the article. It was written carefully, is intelligible, and has passed peer review. And it resolves the SR paradox.

... snip ...

I draw your attention to the point that MRB subscribers who have read the article are apparently not among those still asking questions here. -|Tom|-
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Pay attention, guys and gals. He's right about this.

Regards,
LB

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tvanflandern
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21 years 10 months ago #3865 by tvanflandern

Replied by tvanflandern on topic Reply from Tom Van Flandern

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>don't you mean -
No. All his electrons orbit faster ... because of weaker gravitational potential<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

You are correct. My amendment was incomplete. I've fixed it now. -|Tom|-

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tvanflandern
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21 years 10 months ago #4479 by tvanflandern

Replied by tvanflandern on topic Reply from Tom Van Flandern

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>Is it possible to clarify this issue? If a twin stayed an extended period of time in the moving frame of a GPS clock in space, when he returned to earth would he be older or younger than his counterpart?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Older. The twin in the deeper gravity well (on Earth) ages slower because his electrons orbit slower and all atomic processes (including decay) proceed slower. -|Tom|-

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