In Einstein's General Relativity there are three types of solutions for what happens to our universe, assuming big bang initial conditions for the math.

There is a critical mass density in the solution, which is called omega=1, where if the mass density of the universe is larger than it, the universe will collapse on itself, and if the density is less, the univese will expand forever.

Astronomical observations suggest that the visible star-like mass gives us an omega=0.01. It is thought that there is an additional 0.03-0.04 omega due to black holes, dust brown dwarfs- things we cannot see.

Then here is evidence of dark matter at omega=0.30. So the total omega due to mass, seen and unseen is 0.35 and the universe on that basis will expand forever.

However, in the last few years, it has been found that there is an extra force of expansion in the universe called dark energy that makes omega=1 or close to it.

Nevertheless, dark energy will just increase the expansion rate. If the astronomers are correct, the universe will never collapse or crunch as some would term it.

yanniru

• It Depends On Omega - sagefr0g - March 8, 2003 - 03:23 UTC
  • Perhaps you mean the cyclic universe? - yanniru - March 8, 2003 - 22:05 UTC
    • Paul J. Steinhardt Department of Physics Princeton University - yanniru - March 8, 2003 - 22:07 UTC
    • The Cyclic Universe - sagefr0g - March 9, 2003 - 01:49 UTC
      • They claim its correct physics - yanniru - March 9, 2003 - 02:00 UTC