Understanding Frames of Reference in Relativity

In summary: Train Paradox" in 1905. The paradox is this. Suppose you are on a moving train. You see a stationary light in the distance. According to the special theory of relativity, the stationary light should be behind the train. But it's not. According to the theory, the light has been moving since the moment you saw it. The light has been moving at the same speed as the train. This means that the light has moved since the moment you saw it, and the stationary light in the distance is now behind the train. So, the stationary light has moved backwards in time!)In summary, the relativity of simultaneity states that two events that occur in separate frames of reference cannot
  • #36
MeJennifer said:
That is correct.

All that is happening is that some people want to "explain" relativity by creating 3-planes of simultaneity that gives an enormous source of confusion. Such 3-planes are simply mental constructs as there is nothing physical about them.

A far better description of what is really happening, e.g what is actually measured instead of inferred by such measurements is to use Bondi k-calculus.
This is a pedagogical opinion, one on which all textbook authors seem to disagree with you since they all start out by introducing the notion of inertial frames (and as a matter of pedagogy, aren't the algebraic equations of SR in inertial coordinate systems a bit easier for beginning students than the Bondi k-calculus?) And can you express the idea that the laws of physics must be "Lorentz-invariant" without referring to the notion of inertial coordinate systems constructed in the standard way? If your answer is yes, please provide a reference. If not, that's a major weakness of your approach to thinking about relativity, since Lorentz-invariance is a very important symmetry in physics.
 
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  • #37
JesseM said:
And can you express the idea that the laws of physics must be "Lorentz-invariant" without referring to the notion of inertial coordinate systems constructed in the standard way?
You do realize that Lorentz transformations are coordinate transformations right?
 
  • #38
MeJennifer said:
You do realize that Lorentz transformations are coordinate transformations right?
Sure, but the fact that the equations of the laws of physics are invariant under this transformation and not some other (such as the Galilei transformation) is a real physical symmetry of the laws of nature, just like spatial translation symmetry and time translation symmetry. See Lorentz covariance.
 
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