The Theory Of Everything: The Origin and Fate of the Universe

by Stephen Hawking

The second law of thermodynamics has a rather different status than that of other laws of science. Other laws, such as Newton’s law of gravity, for example, are absolute law—that is, they always hold. On the other hand, the second law is a statistical law—that is, it does not hold always, just in the vast majority of cases. The probability of all the gas molecules in our box being found in one half of the box at a later time is many millions of millions to one, but it could happen.