This is call the critical density, often expressed as omega equals one.

One prediction of the inflation model is that the universe should have a critical density.

The problem is that any small departure from the critical density grows with time, and yet the Universe today remains very close to flat.

Between these two extremes, there is a more attractive possibility, a condition called critical density.

And the Big Bang theory seems to demand critical density.

So there is missing cosmic energy, they said, but not on the order of 80 percent of critical density.

A little taken here, a little put there, to keep it precisely at this critical density?

Unfortunately, critical current densities in these complexes are very small.

The universe's mass, in ordinary and exotic matter, added up to no more than 20 to 30 percent of critical density.

A chain reaction of this sort begins at a point known as the critical density.