Ask A Scientist© Astronomy Archive

Question:  I would like to know as many opinions as possible on the origin and fate
of the universe?
 tim cole

Answer 1:  If you believe the Big Bang Theory then the universe will either:
a) continue to expand forever
b) eventually start to collapse OR
c) "coast" to a stop as time goes to infinity.
The choice of (a), (b), or (c) depends on the Cosmological Constant
designated by cap omega which is related to the Hubble Constant and
is a measure of the mass/energy density of the universe. Basically,
if the universe has enough mass, then its expansion will eventually
stop, and (b) will happen. If the mass is "just right" and cap omega
turns out to be exactly equal to 1.0, then (c) will happen. Some
cosmologists favor (c) on purely esthetic grounds even though the
current best estimate of cap omega is only about 0.1. The "missing mass"
problem is critical to the value of cap omega. This problem comes from
observations that seem to indicate there is more mass in the universe
than we can currently detect.
What you're really asking about is called cosmology. Try looking that up
for some alternative theories.
hawley

Answer 2:  I don't completely agree with answer #1.  What Dr. Hawley is
calling cap omega is not the cosmological constant, but is the ratio
of the total mass of the universe to a magic number (if you've studied
physics, then "mass density" is more correct than "total mass").  His
answer is correct if the cosmological constant, which is another number,
is zero.  If the cosmological constant is not zero, than any "fate of the
universe" is possible, depending upon the value of that constant.
     The precise answer is that the laws of physics will support any opinion
whatsoever.
jlu