RE: expansion of the universe (was Re: JOIN [sl4]: Hello, I'm Mercy.)

From: Jonathan Standley (
Date: Fri Apr 18 2003 - 19:30:54 MDT

"No, I know that part already. What I don't understand is why it isn't
a violation of special or general relativity for that to happen -- so
far as I knew your relative speed to another object in space could
never exceed c. (Or perhaps it is okay because of physics I don't
know. I was sort of reaching for more detail on this.)"
I'm not 100% sure on this myself, but I think it has do to with the fact
that the universe was expanding, which is different from objects moving. If
you were "moving" away from another object because of universal expansion,
you would not have any gain in kinetic energy as a result of the expansion.
You wouldn't be in motion at all.
Again, I could be wrong, but I think this is a good analogy: imagine you are
on a flat sheet of infinitely flexible material. Well, not on the sheet,
but embedded within the sheet, with no way of escaping. You are at one end
of the sheet, and want to travel to the other end. If the sheet is deformed
through the 3rd dimension, stretching it out, the distance between them
increases with no velocity change in the objects relative or absolute
velocity. I drew this little
diagram in b/c of writing this reply, both to help explain the idea, and for
myself as a useful way of visualizing a hard to think about concept :)
J Standley

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