Yes, but
you can't use space as your reference point, as it's, well, space. It's not there.

You have to measure it against the position of something physical to make any sense. This is similar to the argument used to develop the theory of relativity, once Michelson and Morley had disproved the existence of the luminous aether.

Say for example you leave the earth in a rocket travelling at 1000m/s, relative to the earth. You are on your way to rendezvous with a spaceship which is travelling in the same direction at 500m/s.

So your speed relative to the earth is 1000m/s. Your speed relative to the spaceship is 500m/s. Now imagine the earth and spaceship and everything else isn't there. Now what's your speed?

Well, you haven't slowed down or sped up, so your speed must still be 1000m/s...or is it 500m/s? Or is it 10 million m/s relative to the star which was 1000 light years away?

It's undefined. Space isn't a physical entity to measure yourself against.

See my point?

Edit - this is post no. 98. I'm expecting Kaol along shortly...
( K2k6 has a proper job these days, Tue 22 Jul 2008, 16:11, Reply)