21
Physics, Astronomy & Cosmology / Re: Does time dilation and length contraction apply to light?
« on: 06/04/2024 22:18:41 »This was inspired a bit by something I had been corrected about earlier. There was a discussion in another thread about black holes where I stated that black hole singularities had infinite density.That is not correct of course. The exact nature of a black hole singularity depends on the type of black hole it is (charged, rotating, etc), and of course depends on a unified theory which is lacking. In the simplest case, a Schwarzschild black hole is a vacuum solution, so there is no material at all in it at any density. Time simply ends at the singularity, and anything that gets there has no future light cone at all, so it cannot persist as compressed anything.
Things falling into black holes are pulled apart, not squished together. There's not a point where that changes.
Quote
I had been under the assumption that time is frozen for light because it travels at the speed of light.Time is not frozen for it. Time and distance is just not meaningful for light since there is no meaningful reference frame for it.
Quote
Likewise, I had assumed that the entire universe was also length contracted to zero along the light's direction of movement, meaning that it was simultaneously at its starting and ending pointsWhich I suppose is one way to show the absurdities that result from attempting to define a frame where light is both stationary and also by definition moving at c.
Quote
So would it be more correct to say that special relativity doesn't predict the length contraction or time dilation for light?It is not meaningful for a coordinate system in which light (or anything) has an undefined local speed. Length contraction is something meaningful between a pair of inertial frames where things like distance and simultaneity are meaningful.