Answer to Question #156368 in Mechanics | Relativity for Guillem

Question

An empty universe but two bodies attracted by their gravitational pull. The closer and massier they get the stronger they pull. Their speed will only increase.

How can there not be a starting distance d from which the maximum speed of the bodies does not surpasses the speed of light?

Answer 1

As bodies travel faster and faster, they get heavier and heavier – the heavier they get, the harder it is to achieve acceleration, so they never get to the speed of light.