re:Special relativity, the expanding universe and dark energy

From: Ace (rick.oo.groupsrv_at_xemaps-dot-com.no-spam.invalid)
Date: 06/04/04 

Date: 4 Jun 2004 14:39:17 -0500

I thought the big bang theory argued that the universe originated as a
point, and is forever expanding (BTW, the brane theory, involving a
collision between dimensions, seems more coherent to me. The
inflation part of the big bang theory doesn't seem rational.)

If the universe has no outer bound, then what does it mean for it to
be expanding?

Trying to simplify my thought, imagine two objects in orbit around
each other. Both objects are ejecting energetic particles at high
speed, and they are slowly converting mass into energy. So their
mass is going down over time, and the density of mass (and energy) at
a distance is going up. Won't they drift apart from each other as a
result? Or does the symmetry of the change in mass/energy
distribution result in no net change in the forces of gravity acting
on the objects?

I need to learn more about general relativity. I know about
gravitational lensing, but I've never read a concise summary of it
that made any sense to me. Does it come down to the fact that energy
also has gravity? Can anyone summarize GR in a few sentences for me,
or point me to a good source to read about it?

On a related note, I was reading about a dark energy study that's
looking for the disappearance of gravitons as potential proof of
multiple dimensions. I thought gravitons were still theoretical.
Have they actually been observed? How much is known about them?

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