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Twin Paradox revisited

by dubiousraves
Tags: paradox, revisited, twin
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Lightheavyw8t
#19
Jan19-11, 10:19 AM
P: 19
Quote Quote by thwle View Post
(replying to gswellsjr)

gswellsjr, I think Lightheavyw8t conceived of the centrifuge as a control on acceleration so both would experience the same acceleration and only speed would have been different.
Pardon my intrusion, but yes - you have accurately interpreted my intention!
thwle
#20
Jan19-11, 10:22 AM
P: 34
Quote Quote by JesseM View Post
No it doesn't, it only says that traveling relative to a given frame causes one's clock to run slow relative to that frame. When discussing inertial motion, there is no "objective" frame-independent sense in which any particular clock is running slow.

It just means that relative to the synchronized clocks at rest in a given frame which are used to define the "time" of events by a local comparison with the reading on the clock next to the event, the clock moving relative to that frame is running slow. Take a look at this thread where I posted some illustrations of two sets of clocks which define the time of two different frames, and how each frame's clocks sees a given clock from the other set (say, the clock with the red hand) running slow. You can see from the illustrations that the effect is completely symmetrical--each set of clocks measures a clock in the other set to be running slow by the same amount.
I think JesseM is spot on above, but below has interchanged the clocks.

Quote Quote by JesseM View Post
Only in the sense that each observer's frame says the event "my clock shows 10 years elapsed" is assigned the same time-coordinate as the event "other guy's clock shows 223.66 years elapsed, therefore other guy is long dead". But the fact that different frames disagree about which pairs of events share the same time-coordinate is fundamentally no different from the fact that two different spatial coordinate systems which have their axes tilted relative to one another can disagree about whether a pair of points in space share the same x-coordinate.
JesseM
#21
Jan19-11, 10:26 AM
Sci Advisor
P: 8,470
Quote Quote by thwle View Post
I think JesseM is spot on above, but below has interchanged the clocks.
Yes, sorry for the confusion, little mental hiccup there...change that to read:
Only in the sense that each observer's frame says the event "other guy's clock shows 10 years elapsed" is assigned the same time-coordinate as the event "my clock shows 223.66 years elapsed, therefore I am long dead".


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