Lorent's time transformation Feynman 15-6 simultaneity

nitai108
Messages
14
Reaction score
0
Feynman makes an example (15-6 in his lectures) about failure of simultaneity at a distance, using the Lorentz's transformation of time.
A man moving in a spaceship (system S') synchronizes two clocks, placing them at each end of the ship, by a light signal sent from the middle of the ship, and he assumes the clocks are synchronized. An observer in system S reasons that since the ship is moving forward the clock in the front is running away from the signal, and the one in the back is moving toward the signal, therefore the signal reached the rear clock first, and they are not synchronized.

My question is, in the system S' are the clock synchronized? In S the are not synchronized, is this correct?
If the light travels at the same velocity they should be synchronized in S', and because the clocks travel at the same velocity in the spaceship they should read the same time in the S system (but they don't because they are separated by a distance x, which modifies the time transformation in the Lorentz's transformation, is this correct?).
 
Physics news on Phys.org
nitai108 said:
My question is, in the system S' are the clock synchronized? In S the are not synchronized, is this correct?
Yes, and yes. The clocks are synchronized in S' but not in S. This is the relativity of simultaneity, and it is the most difficult concept in SR. Once you get this one down, the rest are easy.
 
Thanks!
 
OK, so this has bugged me for a while about the equivalence principle and the black hole information paradox. If black holes "evaporate" via Hawking radiation, then they cannot exist forever. So, from my external perspective, watching the person fall in, they slow down, freeze, and redshift to "nothing," but never cross the event horizon. Does the equivalence principle say my perspective is valid? If it does, is it possible that that person really never crossed the event horizon? The...
ASSUMPTIONS 1. Two identical clocks A and B in the same inertial frame are stationary relative to each other a fixed distance L apart. Time passes at the same rate for both. 2. Both clocks are able to send/receive light signals and to write/read the send/receive times into signals. 3. The speed of light is anisotropic. METHOD 1. At time t[A1] and time t[B1], clock A sends a light signal to clock B. The clock B time is unknown to A. 2. Clock B receives the signal from A at time t[B2] and...
From $$0 = \delta(g^{\alpha\mu}g_{\mu\nu}) = g^{\alpha\mu} \delta g_{\mu\nu} + g_{\mu\nu} \delta g^{\alpha\mu}$$ we have $$g^{\alpha\mu} \delta g_{\mu\nu} = -g_{\mu\nu} \delta g^{\alpha\mu} \,\, . $$ Multiply both sides by ##g_{\alpha\beta}## to get $$\delta g_{\beta\nu} = -g_{\alpha\beta} g_{\mu\nu} \delta g^{\alpha\mu} \qquad(*)$$ (This is Dirac's eq. (26.9) in "GTR".) On the other hand, the variation ##\delta g^{\alpha\mu} = \bar{g}^{\alpha\mu} - g^{\alpha\mu}## should be a tensor...

Similar threads

Replies
42
Views
737
Replies
39
Views
3K
Replies
54
Views
4K
Replies
6
Views
441
Replies
20
Views
2K
Replies
14
Views
3K
Back
Top