Thursday, September 12, 2013

The Day the World Changed...or, at least, one of them

Yesterday's 12th anniversary of the 9/11 terrorist attacks in New York City, Washington, DC, and Pennsylvania, remind of all the rhetoric that was created about that day being "the day the world changed" and that "nothing will ever be the same", as if these turning points are rare and are always loud and immediately evident.

But today, September 12, is the anniversary of such a day, one that is rarely remembered and even more rarely commented on. The event that happened on this day was quiet and personal and flowered slowly, but it changed history and the way that Western culture looks at the world forever, and with much more far-reaching consequences.

On this date in 1933, the Hungarian-born American physicist Leo Szilard first had the idea of a nuclear chain reaction, the process that is necessary for the generation of nuclear energy and that enables nuclear bombs to explode with almost unimaginable power.

Szilard, who was in London at the time, had read that morning in The Times of London, a summary of a speech given by Ernest Rutherford, another physicist, in which Rutherford rejected nuclear energy as a practical way of generating power. This rejection annoyed Szilard, and he began thinking about the problem as he took one of his customary walks. As he later told the story, as he was crossing a street during that walk, he suddenly had a mental picture of how a nuclear chain reaction could be accomplished. It wasn't the first time anyone had thought about the possibility of such a reaction. That had, as far as we know, first been proposed in 1913. But, as a practical matter, it was Szilard's sudden idea that opened the door to making nuclear chain reactions achievable.

Achieving a chain reaction didn't occur overnight, of course, and it wasn't until 1939 that Szilard and Enrico Fermi discovered neutron multiplication in uranium, showing that a nuclear chain reaction was possible. Szilard and Fermi went on to create the first artificial, self-sustaining nuclear chain reaction in late 1942. But even before that, in 1939, very soon after discovering that such a reaction was possible and fearing that the Nazis would discover the same thing and try to exploit it, Szilard wrote a letter to be signed by Albert Einstein and delivered to President Franklin D. Roosevelt, urging the US government to begin research into building an atomic bomb. That letter led, eventually, to the creation of the Manhattan Project and the creation of nuclear weapons.

Szilard seems to have had some regrets later about the letter, as the research into the atomic bomb became more controlled by the US military than by the scientists who were doing the work. He was also an advocate, once the bomb had been created, of conducting a demonstration explosion to show the power of the new device in an attempt to convince the Japanese to halt the war (the Trinity test that showed that the atomic bomb did indeed work did not come until after world War II had ended in Germany), instead of directly bombing Japan, as ultimately happened;.

After the war, Szilard abandoned nuclear physics and turned his attention to molecular biology. He also continued to insist that the use in battle of the atomic bomb had not been necessary if only the US had been willing to demonstrate it away from populated areas.

So. Change happens. Every single day, in many ways, good and bad, for individuals and for groups and, sometimes, for the whole of mankind. Often we don't notice those changes until well after the fact. I'm sure that Szilard had some idea, right away, that if his idea worked, life as we know it would change forever. The rest of the world, not so much. It took over a decade from that walk Szilard took after reading something that annoyed him for events to take their course. On the other hand, if Szilard had not read that article and had not been thinking, consciously or unconsciously, about the problem of how to get energy out of nuclear reactions, and if he had not had that sudden insight, history might have turned out very, very differently.

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