Micro vs Macro


This symmetry between forward and reverse paths highlights the distinction between the microscopic world of a single molecule and our macroscopic world. For a single molecule path in which the entropy increase is twenty, we only see the reverse path twice for every billion times we observe the forward path. So the relative likelihood of the reverse path to the forward path is one divided by five hundred million, a very small number. The reverse path is incredibly unlikely. A pot is much, much larger than an RNA molecule, and its total entropy upon breaking is correspondingly larger. We can also express the relative likelihood of the unbreaking of the pot as one divided by a large number. This large number dwarfs the total number of atoms in the universe, which can be written as a one with eighty-one zeros after it.

To quantify the vastness of this number, consider a strip of paper and my wife's engagement ring. After a leading one, I write a zero for every eighth carbon atom in the diamond. This strip of paper would stretch five hundred twenty-eight light years out into space, reaching outside of our Milky Way Galaxy. If I wrote two zeros every second, it would take 15 trillion years to finish writing this number. One divided by this large number is quite small, so unbreaking a pot is incredibly, incredibly unlikely.