E=mc2 (28 page)

What's more serious—or at least, what seems explicable only by Hahn's realizing he'd done something very wrong—was the way Hahn tried
to
rewrite the history of his relation with Meitner after the war: treating her as having been some sort of junior assistant when he was interviewed by Swedish newspapers in Stockholm in the week before his Nobel Prize ceremony in 1946; later, giving mocking, almost sighing references to how foolishly misguided her attempted advice had been. Meitner suspected it was all a way of Hahn exculpating himself—for if she'd hardly been there at all, how could he be charged with having treated her badly? See Sime,
Lise Meitner,
Chapters 8 and 14, and especially her note 26 on page 454.

". . . in the lurch": Ibid., p. 185.

"Hahn says I should not . . .": Ibid.

Hahn, as ever, seemed the slowest. . . : After the outlines of fission had been worked out, he still had troubles: "Bohr will perhaps think I'm a cretin," Hahn wrote to Meitner in July 1939, "but even after 2 of his long explanations I again don't understand it." As with Lawrence, though, the question is one of degree. Hahn was an intelligent enough man—he just wasn't at Meitner's level. What he was exceptionally good at, though, was judging when a field was ripe. That's indispensable. It was not entirely by chance that he "happened" to be at Rutherford's Montreal lab, just when it was possible for a skilled chemist like himself to discover a new element; nor that he was at the new institutes on the edge of Berlin when those were the most fruitful places for a chemist with his background to be.

Peter Medawar called this importance of appropriate selection "the art of the soluble." The point is not that only easy problems are targeted; rather, "the art of research [is] the art of making difficult problems soluble by devising means of getting at them." Einstein when young was superb at this; Rutherford kept the ability his whole life. The Medawar quote is on page 2 of his justly lauded
Pluto's Republic
(Oxford: Oxford University Press, 1984).

"Meitner's opinion and judgment . . .": Watkins, p. 185.

Hahn's letter of December 19,1938, to Meitner: Sime,
Lise Meitner,
pp. 233-34.

"Meitner was the intellectual leader . . .": Ibid., p. 241.

"You see, you will do a good deed . . .": Ibid., p. 234.

Robert Frisch: Many texts speak of someone named Otto Frisch, who confusingly seems to have been related-nephew perhaps?—to an earlier physicist named Robert Frisch. They're one and the same. As a young man, Robert Otto Frisch had used his first name, but when he later ended up working with Americans, for whom the name Robert was so common, Frisch decided being known by his middle name would be less confusing.

"Fast, but not auntie": Otto Frisch,
What Little I Remember
(Cambridge: Cambridge University Press, 1979), P. 33.

The next morning, when he came down . . . : What happened at breakfast and then during their famous walk in the snow has been extensively recounted by the two participants. See the Frisch and Meitner items in the Guide to Further Reading, as well as the bibliographic notes at Sime,
Lise Meitner,
p. 455, and Richard Rhodes,
The Making of the Atomic Bomb,
p. 810, entry 257.

". . . that she could walk just as fast without": Frisch,
What Little I Remember,
p. 116.

"so overwhelmingly new and surprising": Lise Meitner, "Looking Back,"
Bulletin of the Atomic Scientists
(Nov. 1964), p. 4.

"Fortunately [my aunt] remembered . . .": Frisch,
What Little I Remember,
p. 116. Meitner knew this from earlier published measurements of nuclear weights.

The
lahel fission . . .:
The biological analogy was a common one: Rutherford had chosen the word
nucleus for
the center of an atom on the same basis.

10. Germany's Turn

Einstein's letter of August 2,1939: The letter is in most Einstein biographies or histories; see, e.g.,
Einstein: A Centenary Volume, ed.
A. P. French (London: Heinemann, 1979), p.191, for a clear facsimile. The story of how Einstein came to sign the letter is given with exuberant detail in Leo Szilard,
The Collected Works
(Cambridge, Mass.: MIT Press, 1972), though with somewhat more accuracy in Eugene Wigner,
The Recollections of Eugene P. Wigner
(as told to Andrew Szanton) (New York: Plenum Press, 1992).

Roosevelt's letter of October 19, 1939, in
Einstein on Peace, ed.
Otto Nathan and Heinz Norden (New York: Simon & Schuster, 1960), p. 297.

"I received a report. . .": This diary entry jumps ahead from the main narrative; Goebbels made it in 1942, after the February meeting where Heisenberg made a powerful presentation to a number of Nazi officials, explaining how easily one could proceed with a bomb.

. . . he'd always faithfully rejected the job offers . . . : See, David Cassidy,
Uncertainty: The Life and Science of Werner Heisenberg
(New York: Freeman, 1992), pp. 412-14.

. . . his wife later said he had nightmares . . . : Ibid., p. 390.

"Oh, you know, Mrs. Himmler . . .": Alan Beyerchen,
Scientists Under Hitler
(New Haven, Conn.: Yale University Press, 1977), pp. 159-60. The interview with Beyerchen took place 34 years after the events; possibly Heisenberg's playing up his mother's naïveté.

"Very Esteemed Herr Professor . . .": The letter is reproduced in Samuel Goudsmit,
Alsos: The Failure in German Science
(London: Sigma Books, 1947), p. 119.

What would have been a near miss . . . : This is the operation of the famous Uncertainty Principle, which had been worked out largely by Heisenberg in the mid-1920s. It's an odd effect—but central to how E = mc
²
came to finally be removed from the laboratory, and turned into such an overpowering force on Earth. It's also, like E = mc
²
, one of those immensely powerful equations that can be written out in a brief space; in its essence it's simply ?x.?v?h. The ?x is the inexactitude in measuring where a particle is, and ?v is the inexactitude in measuring the velocity at which it's moving. (The symbol "h" is the extremely small figure known as Planck's constant.)

What the ? in the equation says is that reality's accuracy has a little seesaw or teeter-totter built into it. If you start measuring a particle's location more accurately, then you'll start measuring its velocity less accurately, and vice versa. When one goes up, the other goes down.

This has no direct effect on the large objects around us in ordinary life, but on the micro level, and in what Heisenberg was trying to do in 1940, it's crucial. If you slow down a neutron that you're propelling at a target, then you'll be able to measure its velocity more accurately than you could before. By the "teeter-totter" of the Uncertainty Principle, however, this means you won't be able to measure its location as accurately. In symbols, as the ?v gets less, the ?x gets bigger.

That might seem just a matter of clever words, but—as with the curios of relativity in our earlier chapters—it really does come true. Because Ax is larger, there's a greater spread in our possibility of specifying the neutron's location.
That means its interaction with the target changes.
For what is a fruitful definition of an incoming object's size? Simply how likely it is that it'll contact the nucleus it's being shot at.

It can be irritating to think that this is as good a definition of "size" as one can get, but again, think of the way that in special relativity there was no objective background or "true" time within which events could be placed. To feel that there is a "true" size that can be measured is, indeed, in itself a violation of the Uncertainty Principle. Thus a baseball glove or cricket glove allows you to catch balls which otherwise you would have missed: the size of your hand has effectively increased, due to the extra webbing. But if a viewer knew very little about the game, and just caught a quick blur of the catch on a TV screen, it would be just as plausible for the viewer to conclude that it was the ball that had enlarged, and that this was why fielders could suddenly make such spectacular catches.

With the Uncertainty Principle, there's no way of getting past that blur. The incoming neutron has slowed down, the likelihood of there being a "catch" has gone up— and that's as much explanation as we're going to get of why the target has "become" larger. (In real life the Principle is probabilistic, and the effective "widening" only applies to a sequence of neutrons being shot out.)

The Uncertainty Principle was fundamental to how E=mc
²
was released, for it was used in many other calculations needed to construct a bomb. (The electrons in an atom, for example, can't be going too fast—they'd fly away, otherwise—but that constraint on their speed means there's a decreased detail available for any calculations about their actual location within an atom.)

"Germany has actually stopped the sale . . .": The letter is widely quoted. See, e.g.,
Einstein: A Centenary Volume, ed.
A. P. French, p. 191.

But Heisenberg had a procurement organization . . .: Much of the timing is clarified in Mark Walker's
German National Socialism and the quest for nuclear power 1939-1949
(Cambridge: Cambridge University Press, 1989); see especially pp. 132-3. It was in 1943 that the women were "bought" from Sachsenhausen; at the same time, Russian prisoners of war were being used in other aspects of the bomb project (they were forced to work, for example, on Bagge's isotope sluice). Late in the war, when parts of the Kaiser Wilhelm Institute for Physics was being relocated to the Hechingen area, Heisenberg was informed that Polish slave labor would be available.

. . . female "slaves": With the passage of time, it is easy to forget what attitudes the individuals who worked in Germany during the war were accepting; what words like
bought
and
slave
actually meant. There are tens of thousands of pages in the Nuremberg Trial documentation; on November 15, 1947, the New York
Herald Tribune
reported the firsthand testimony behind just one:

Nuremberg, November 14,1947 (A.P.) A French witness testified today that the I. G Farben combine purchased 150 women from the Oswiecim [Auschwitz] concentration camp>after complaining about a price 0/200 marks (then $80.00) each, and killed all of them in experiments with a soporific drug.

The witness was Gregoire M. Afrine. He told the American military tribunal trying 23 Farben directors on war crimes charges that he was employed as an interpreter by the Russians after they overran the Oswiecim camp in January 1945 and found a number of letters there. Among the letters, he said, were some addressed from Farben s "Bayer"plant to the Nazi commandant of the camp. These excerpts were offered in evidence:

1. In contemplation of experiments with a new soporific drug we would appreciate your procuring for us a number of women.

2. We received your answer but consider the price of 200 marks a woman excessive. We propose to pay not more than iyo marks a head. If agreeable, we will take possession of the women. We need approximately 150.

3. We acknowledge your accord. Prepare for us 150 women in the best possible condition, and as soon asyou advise us you are ready we will take charge of them.

4. Received the order ofiyo women. Despite their emaciated condition, they were found satisfactory. We shall keep you posted on developments concerning the experiment.

5. The tests were made. All subjects died. We shall contact you shortly on the subject of a new load.

"I have now learned that research . . .":
Einstein on Peace,
Otto Nathan and Hans Norden (New York: Schocken, 1968), p. 299.

". . . this office would not recommend the employment of Dr. Einstein . . .": Richard A. Schwartz, "Einstein and the War Department,"
Isis,
80, 302 (June 1989), pp. 282-83.

Lawrence was not especially bright . . . : Again, as with Hahn, brightness is a relative matter. Lawrence understood his own limitations—"You've got to practically crucify yourself if you're going to amount to anything" he'd explained to an assistant when he was first teaching at Berkeley (in Nuel Phar Davis,
Lawrence and Oppenheimer,
London: Jonathan Cape, 1969, p. 16)—and, in part, as a result Lawrence was exceptionally keen on tracking outside developments which he could incorporate for his own work. His great success was improving a Norwegian's method for accelerating charged particles—it was the basis of the cyclotron, and ultimately what won him his Nobel Prize. Such anxious "borrowing" is central to one sort of successful lab: See Kealey's
Economic Laws of Scientific Research
in the Guide to Further Reading for Chapters 8 and 9.

"a tiny cube of uranium . . .": Davis,
Lawrence and Oppenheimer,
p. 99.

. . . a practical engineering degree . . . : Wigner,
Recollections of Eugene P. Wigner
(New York: Plenum Press, 1992), pp. 59-62. The caution was widespread: even the intellectually awesome von Neumann took a chemical engineering qualification along with his doctorate in mathematics summa cum laude. Einstein also kept involved in practical inventions—a better electrical current monitor; an improved refrigerator—in part for similar reasons.

What shape . . . should the uranium be . . . : The points are presented on p. 40 of Jeremy Bernstein's introduction to his
Hitler's Uranium Club.
Bernstein's work has been central to my understanding of German work on the bomb; I've drawn on it throughout these chapters. Note that when other teams in Germany showed that cubes were in fact the more efficient shape, Heisenberg resisted their findings till most of the war was over—much like his suppression of the views of German researchers who argued for moderators other than the heavy water he preferred.

. . . flat surfaces . . . have the easiest properties to compute . . . : It's a common weakness. The F-117 Stealth fighter, for example, has sharp angular lines not because they're especially aerodynamic—they're not—but because the 1970s computers that were used to analyze its properties couldn't handle anything more rounded. See Ben Rich and Leo Janos,
Skunk Works: A Personal Memoir of My Years at Lockheed
(Boston: Little, Brown, 1994), p. 21.