In the Routledge Encyclopedia of Philosophy, “Heisenberg, Werner” lies between “Heidegger, Martin” and “Hell.” That is where he belongs. Heisenberg, one of the inventors of quantum mechanics, was the leader of Hitler’s atomic bomb project. After the war, he claimed that he had sabotaged the Nazi bomb effort. Many believed him. But last month, his protestations of innocence (indeed, valour) were revealed to have been almost certainly a lie. Letters written by the Danish physicist Niels Bohr, released for the first time, make it pretty clear that Heisenberg was doing everything he could to produce a nuclear weapon for the Third Reich. His failure was due not to covert heroism but to incompetence.
Heisenberg (1901-76) was a wonderful physicist. At the age of 24, in a rapture on a rock overlooking the North Sea, he had an insight that revolutionised our understanding of the subatomic world. Two years later he announced, in what is probably the most quoted paper in the history of physics, his “uncertainty principle.” Today, even the greatest physicists admit to bafflement at Heisenberg’s mathematical non sequiturs and leaps of logic.
Though he may have been a magician as a theorist, Heisenberg was something of a dunce at applied physics. His doctoral exam in 1923 was a disaster. When, during the war, Heisenberg tried to determine how much fissionable uranium would be necessary for a bomb, he came up with the impossible figure of several tons. (The Hiroshima bomb required only 56 kilograms.) This is not the kind of scientist you want to put in charge of a weapons project.
Those who, prior to last month’s revelation about Heisenberg, wished to stress the supposed murkiness of his wartime motives often reached for a metaphor from his physics: the uncertainty principle. Michael Frayn did it in Copenhagen, his play about a 1941 encounter between Heisenberg and Bohr. Thomas Powers did it in Heisenberg’s War, the 1993 book that defended Heisenberg’s claim to have destroyed the Nazi bomb project from within. David C Cassidy did it in his 1991 biography of Heisenberg, Uncertainty. They should all have known better.
And they’re hardly alone. No scientific idea from the last century is more fetishised, abused, and misunderstood-by the vulgar and the learned alike-than Heisenberg’s uncertainty principle. The principle doesn’t say anything about how precisely any particular thing can be known. It does say that some pairs of properties are…