Tuesday, May 25, 2010

A Quiet Beginning To A Giant Explosion

I am reading E = mc2 A Biography of the World's Most Famous Equation by David Bodanis.

Here is a passage about the pivotal moment in 1938 in Sweden when Lise Meitner and her nephew Robert Frisch worked out how much energy is released by the fission of one uranium nucleus:

...Fortunately [ my aunt] remembered how to compute the masses of nuclei.... and in that way she worked out that the two nuclei formed by the division of a uranium nucleus would be lighter than the original uranium nucleus, by about one-fifth the mass of a proton. Now whenever mass disappears, energy is created, according to Einstein's formula E = mc2  ....

..They had crossed a river on their walk out from Kungalv and it was frozen. The village was too far away to hear any market noises. Meitner did the calculation. Frisch remembers later: " One-fifth of a proton mass was just equivalent  to 200 MeV. So here was the source of that energy; it all fitted!"

The atom was open. Everyone has been wrong before. The way in wasn't by blasting harder and harder fragments at it. One women and her nephew, quiet in the midday snow, had now seen that.

The equation is always linked to Einstein and his work... but this book explores the role of physicists and chemists going back to Lavoisier, Faraday and Maxwell among others whose work on mass and energy built the foundation Einstein stood on and a later cast of characters who worked out the broader implications of the equation.

The added attraction is a suspenseful commando raid that destroyed Germany's heavy water supply essential to its growing nuclear program.

..Terrific stuff..

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