Question: How is it that galaxies that are red shifting appear to be moving away at light speed or faster when the laws of physics state that time travel is impossible?
I don’t think there’s any good evidence that things can actually travel faster than light. But in an expanding universe, the further apart two object are, the faster they are moving apart (you can test this by drawing pairs of dots on a balloon and blowing it up.
So if two galaxies are moving apart from one another, each at 0.75 the speed of light, I suppose their relative speed of separation would be 1.5 times light-speed.
But all that is mere conjecture on my part – I’m not an astrophysicist.
I answered a similar question earlier, and I’m going to say the same thing even though another student came back with a very complicated quote suggesting I should think again. (Health Warning: I Am Not A Physicist)
As you know distant galaxies, like our own Milky Way are carried along by the expansion of the Universe, and will move apart from every other galaxy. As you look at galaxies further and further away, they appear to be moving faster and faster away from us. So is it possible that they could eventually appear to be moving away from us faster than the speed of light? Don’t panic Einstein’s theory is not broken! The galaxies themselves aren’t actually moving very quickly through space, it’s the space itself which is expanding away, and the galaxy is being carried along with it. As long as the galaxy doesn’t try to move quickly through space, no physical laws are broken.
Comments
yourmum commented on :
@ Pete, So space itself is moving at the speed of light?