Impossible to answer?

[dsliscoo]

Originally Posted by ledwix

Actually, the curvature of the universe is not a term relating directly to the geometric shape of it, if I recall correctly. It refers to something regarding the average matter/energy density of the universe. A flat universe is one in which the mass/energy density hovers or stays very close to a critical value and therefore, once the cosmos reaches a maximum size, all expansion stops, and the universe stays the same size for the rest of eternity. Curvature can be either positive or negative. Positive curvature implies that the mass/energy density of the universe is higher than some critical value, and therefore, there is enough mass in the universe to make it collapse back into itself after a certain point. Negative curvature implies that the initial expansion forces and the cosmological constant propel the universe outward forever, as the forces of gravity drop off and become too weak compared to the cosmological constant. Under this scenario, the universe expands forever.

I believe the term curvature itself is used because of the way gravity (i.e. mass) causes curvatures and distortions in spacetime according to relativity.

uhm critical mass of one is a flat universe that will not expand or contract. Below one and the universe will expand and >1 and it will eventually expand to far to the "big chill". I am fairly certain they don't use gravity to figure out what that number is, because the known gravity in the universe pales in comparison to the energy that should be in this universe for it to be as close to one as it is.

in case that doesnt make sense...

1 = flat universe/not changing
<1 = expanding forever
>1 = contracting
our universe ~= .05 - .2(known mass)
our universe is supposed to equal somewhere really close to 1. (10^15 decimil places)

The way i was reading the measure of curvature was talking about the actual shape of the universe not really the distances between points in space and whether or not they are getting closer or farther from each other.
If they were trying to measure that a laser wouldn't work. Two things would probably happen. Either light would appear to speed up because the space has shrunk(or slow down if it has grown) or more then likely the effects wouildn't be measureable with them.

Either way, i really don't think the universe is expanding or cointracting I think the universe has been this way for a very long time.