Crick, Watson, Franklin and Szillard

James Watson died yesterday.  He was the last of the people responsible for discovering the Double Helix structure.  Watson and Francis Crick won the 1962 Nobel Prize in Physiology and Medicine for their discovery, which is one of the most important of all time.

There are two other people who deserve mention.  Most people are aware of the previous work done by Rosalind Franklin, who unfortunately died 1958 but would have certainly deserved a share of the prize. 

The other important contributor was Leo Szilard.  Szilard's most famous achievement was realizing that nuclear decay is caused by a neutron chain reaction, and that by manipulating the density of neutron emitters, you could control the rate of nuclear fission, right up to, and including a runaway explosion, which became known as the Atom Bomb.  Fermi's experiments a few years later led to the first Nuclear Pile in 1938, and in 1945, the first Atom Bomb.  Szilard intentionally kept his idea for the bomb secret because he was terrified of the Nazis getting the A-Bomb first, but he and his friend Einstein wrote a letter to Franklin Roosevelt, which motivated the creation of the Manhattan Project.  Szilard and Einstein were specifically kept out of it to try to keep the Nazis from pursuing the idea.  Turned out Hitler regarded this stuff as "Jewish Science" and had effectively blocked progress in his country (Szilard and Einstein, along with Openheimer, Fermi's wife, and many of the others involved were Jewish), but he had no way of knowing that, having fled to England in 1933 and America in 1938.

 Szilard's contribution to the discovery of DNA were severalfold.  He invented the electron microscope in 1928, which made it possible to see some detail in chromosomes for the first time.   And it was he that devised the XRay diffraction technique which Franklin and others would use to work out the physical structure of DNA.

I regard Szilard, who died of a heart attack in 1964 at age 66, as perhaps the greatest scientist of the 20th century, in a league with only Einstein, Tesla, and Louis Alvarez.