The mathematical physicist Paul Davies, a professor at the
University of Adelaide in Australia, performed lengthy calculations of the
conditions that must have existed at the moment of the Big Bang and came up with
a result that can only be described as astonishing. According to Davies, if
the rate of expansion had differed by more than 10-18 seconds (one quintillionth
of a second), there would have been no universe. Davies describes his
conclusion:
Careful measurements puts the rate of expansion very close to a critical value
at which the universe will just escape its own gravity and expand forever. A
little slower and the cosmos would collapse, a little faster and the cosmic
material would have long ago completely dispersed. It is interesting to ask
precisely how delicately the rate of expansion has been "fine tuned" to fall on
this narrow dividing line between two catastrophes. If at time I S (by which the
time pattern of expansion was already firmly established) the expansion rate had
differed from its actual value by more than 10-18, it would have been sufficient
to throw the delicate balance out. The explosive vigour of the universe is thus
matched with almost unbelievable accuracy to its gravitating power. The big
bang was not evidently, any old bang, but an explosion of exquisitely arranged
magnitude
Source:
http://www.creationofuniverse.com/html/equilibrium01.html