PHYS 230 Chap 5 Sec 2 - Relativity of Simultaneity

Chapter 5 - Relativity
Sec 2 - Relativity of Simultaneity

[ipergiovanni]

Here is my variant of Einstein's famous train which denies the physical existence of relative simultaneity, the latter being an indispensable premise of Einstein's kinematic length contraction and Einstein's kinematic time dilation

Bob stands in the middle of the station and Alice stands in the middle of the train.

As the train passes through the station and Bob is squarely in front of Alice, two lightning strikes the head and tail of the train.

Bob says to Alice:

- "two lightning bolts simultaneously struck the train, but not for you, because you, advancing together with the train, saw the light wave front arriving from the front of the train first and then the one from the rear of the train".

Alice says to Bob:

- "you are mad, look, even though I was asleep at that moment I am able to prove you wrong, and in fact when the two lightning strikes woke me up, I went to look at the clock placed at the head of the train and the clock placed at the end of the train, well, both were broken simultaneously by the two lightning strikes because both clocks kept the same time."

Giovanni from Italy.

[juliavixen]

Not to be pedantic, but... H. Poincaré, in 1900, pointed out in his rebuttal to H. Lorentz's theory (mostly about how an emitter of directed EM waves must recoil in the opposite direction) that a moving observer will not be able to synchronize their own clock to any pair of synchronized clocks located at some great distance apart from each other.

He still insists however that there must be an (unmeasurable) universal clock in the reference frame of the aether, even though observers can only measure their own "local time". Einstein just said there's no aether, and it's only local time is necessary for everyone everywhere. (Remarkably, almost all of Einstein's arguments are the same as Poincaré's, except without any appeals to any kind of incompressible dielectric fluid filling every location of space.)