Famous First Words #6: Fission -- Meitner and Frisch

Famous First Words is a recurring LabKitty feature that takes a look at the opening line of an historic scientific article.

When Einstein was confronted after the fact that his famous equation of mass/energy equivalence pointed to way to the release of unimaginable quantities of energy and maybe not in a good way, do you know what he said? He said: Daran habe ich gar nicht gedacht! That's roughly German for GTFO. Such a release would require splitting the atom, a feat most theorists of the day viewed as impossible. Rutherford -- the Father of Nuclear Physics -- famously dismissed talk of the large-scale release of nuclear energy as "moonshine." He would not live to see himself proved wrong, dying in 1937 after falling from a tree he was pruning (no kidding).

As usual, the experimentalists spoiled the party. Otto Hahn and Fritz Straussman bombarded uranium with neutrons, and what kept coming out was something chemically identical to barium. Which was ridiculous. Rutherford had demonstrated it was possible to transmute elements, but his products only shifted one or two slots in the periodic table. Barium was less than half the size of uranium. What the Hector Lonzo was going on?

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Hahn shows his results to Lise Meitner, one the most capable physicists of the day. She mulls them over and concludes that Hahn and Straussman weren't just chipping off a few particles like Rutherford had done, but rather had cleaved (the word "fission" had yet to be invented) the nucleus in two (or almost in two -- fission tends to create two slightly unequal-sized products). The sum of the mass of the products is less than the original uranium nucleus by about 1/5 of that of a proton, the deficit released as energy according to e = mc^2. The energy, the chemistry, the physics. It all fit.

Meitner and her nephew Otto Frisch send a paper off to Nature, announcing the beginning of the nuclear age. For her efforts, the Nobel folks award the prize to Otto Hahn. Wait, what? Yes, this was the era when academics was a man's world and the wimmen physicists were expected to smell nice and fetch the sammiches, a tradition extending back to Mileva Einstein and Emmy Noether and ahead to Leona Marshall and Rosalind Franklin. Pioneers like Meitner would begin to level the playing field through sheer talent. (Meitner and Madame Curie were sort of the Ann and Nancy Wilson of nuclear physics.)

Here's the opening of Meitner and Frisch's paper:

Disintegration of uranium by neutrons:
a new type of nuclear reaction
Lise Meitner & O. R. Frisch
Nature 143:239 (1939)

In making chemical assignments, it was always assumed that these radioactive bodies had atomic numbers near that of the element bombarded, since only particles with one or two charges were known to be emitted from nuclei.

Image of Otto Hahn's experimental apparatus from the Nuclear Fission Deutsches Museum by Jacopo Werther and appears under the Creative Commons Attribution-Share Alike 2.0 Generic license.