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IntuitioN

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How does this work? It seems impossible that both clocks can run slower.

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- Thread starter IntuitioN
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- #1

IntuitioN

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How does this work? It seems impossible that both clocks can run slower.

- #2

ramollari

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https://www.physicsforums.com/showthread.php?t=61640

https://www.physicsforums.com/showthread.php?t=49092

There exist a variety of explanations to this paradox, which don't seem to be completely satisfactory.

- #3

HallsofIvy

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- #4

Doc Al

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To begin understanding how each observerIntuitioN said:How does this work? It seems impossible that both clocks can run slower.

(1) moving clocks are measured to run slow

(2) moving metersticks (or anything with length) are measured to be shorter (along the direction of motion)

(3) moving clocks that are synchronized in their own frame are measured to be out of synch

Each of these effects are completely symmetric. Observer A will say that Observer B's clocks run slow (as measured by A) and Observer B will say the same about A's clocks. Same for the other two effects. Effect #3, clock desynchronization, is the most subtle.(2) moving metersticks (or anything with length) are measured to be shorter (along the direction of motion)

(3) moving clocks that are synchronized in their own frame are measured to be out of synch

It is only by combining all three of these effects that things will make sense. I recommend consulting any of the many elementary books on special relativity available for a detailed explanation.

Another place to start is with a website that explains time dilation using the infamous "light clock": http://landau1.phys.virginia.edu/classes/109/lectures/srelwhat.html

That links to a short lecture that covers time dilation; the followup lecture explains clock synchronization and simultaneity; the third explains how it all fits together. Be sure to look at all three!

PS: I don't think IntuitioN had the twin paradox in mind when he asked his question. (That will just add confusion, at this point.)

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- #5

ramollari

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I just wanted to inform the thread starter about the name of the paradox and that it is well known. Yes, probably he wanted a more basic introduction to time dilation and the twin paradox.Doc Al said:PS: I don't think IntuitioN had the twin paradox in mind when he asked his question. (That will just add confusion, at this point.)

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Doc Al

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I understand. My point is that the example given in the first post wasramollari said:I just wanted to inform the thread starter about the name of the paradox and that it is well known. Yes, probably he wanted a more basic introduction to time dilation and the twin paradox.

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ramollari

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