# Relative velocity

1. Sep 17, 2008

### epkid08

What is our relative velocity with respect to the largest mass in the universe?

Can this velocity exceed the speed of light, as the force accelerating us is strictly gravitational?

If it's possible, wouldn't us, traveling at or faster than c, be a better reason for why only a fraction of our universe is observable, than the theory that the universe is expanding at or faster than c?

2. Sep 17, 2008

### Staff: Mentor

That's a strange question. The distribution of matter in the universe is farily homogenous on the large scale, so it doesn't mean much to ask about "the largest mass in the universe".

In any case, due to the expansion of space, it is possible for us to have an apparent velocity of greater than C wrt very distant objects.

Your last sentence doesn't make much sense either - all velocities are relative, so it typically makes the most sense to consider ourselves stationary and all objects around us to be moving away from us. And remember, regardless of any motion we measure wrt any object, light always travels at C so our visible universe will always be perfectly spherical.