The Universe as an Engine

Slide 13 of 22

The reason that the universe would not "bounce" if it were to contract is that the universe is extremely inefficient (entropic). In fact, the universe is so inefficient that the bounce resulting from the collapse of the universe would be only 0.00000001% of the original Big Bang (see table above). Such a small "bounce" would result in an almost immediate re-collapse of the universe into one giant black hole for the rest of eternity.

Guth, A.H. and M. Sher. 1983. The impossibility of a bouncing universe. Nature 302: 505-506.