Question

Does Lorentz contraction counteract space expansion?

Answer 1

Suppose Andromeda is at rest relative to earth. You are on earth, holding your ruler, which just touches Andromeda.

Now you instantly start traveling toward Andromeda at a high speed. Your ruler, of course, travels with you, still pointing toward Andromeda.

Your journey just began an instant ago, so neither you nor your ruler has yet moved appreciably. I, sitting on earth, say "I see that the end of your ruler just touches Andromeda". I also say that "In a little while, the far end of your ruler will extend way past Andromeda".

But because you're traveling relative to me, we have different notions of simultaneity. While Isay that in a while your ruler will extend past Andromeda, you see that event as occurring right now.

So as far as you're concerned, Andromeda, instead of being at the end of the ruler (marked 25 million) is now at the point marked 20.

You haven't seen Andromeda move; you've just seen a change in what your ruler measures.

The laws of physics say that you can travel from here to "20" on your ruler in just a little over 20 years. Enjoy your journey.

Answer 2

At any point in space the Lorentz transformation is linear, and then youcan define local" Lorentz invariance at any point in space. ... In strong gravitational field there is a huge amount of the rest mass change to photons which required to define the escape velocity as a relativistic, not classical as in Einstein GR.