There are more possible iterations of chess games than there are atoms in the observable universe.

There are more possible iterations of chess games than there are atoms in the observable universe.

Mitesh Patel

4, June, 19

INSPIRATION & LEARNING, STARTLING FACTS

This value, known as the Shannon Number, represents all of the possible move variations in the game of chess. It is estimated to be between 10^111 and 10^123. By comparison, there are 10^81 atoms that make up the known universe. 

Source: http://www.realclear.com/science/2013/07/08/astounding_facts_that_not_everybody_appreciates_2204.html