Question: Why didn't the Germans build the atomic bomb in World War II?
Answer: There are competing theories, but the one we like the most is that they made a mental error. A computational blunder. Imagine! The fate of civilization, turning on a misplaced digit, a rogue integer, a bit of slop in a back-of-the-envelope calculation.
The historical debate over the German bomb program centers on Werner Heisenberg, he of the famous Uncertainty Principle (which is something like, "When in doubt, don't major in physics"). Although many of Germany's leading scientists fled the country soon after Hitler came to power in the 1930s, Heisenberg and many others remained, and they knew as much as their Allied counterparts about the frightening power locked within the atom. But they never came close to building a bomb. Why not?
Morality, perhaps. The American journalist Thomas Powers has argued in a new book, "Heisenberg's War: The Secret History of the German Bomb," that Heisenberg had moral objections to the Nazi regime and intentionally suppressed the German bomb effort. His evidence is circumstantial. For example, in 1941 Heisenberg leaked word of the German bomb program to a colleague in the West, in gross violation of security. And in discussions with Albert Speer, Hitler's closest adviser, Heisenberg appeared to exaggerate the difficulty of building a bomb and said a successful bomb might even cause the entire planet to catch on fire.
But Heisenberg repeatedly said in later years that he had no moral qualms with the bomb. He said it appeared too daunting during wartime conditions, with Germany under bombardment and resources stretched. We spoke to several veterans of the Manhattan Project and they all cited the official Heisenberg explanation, that Germany didn't have the resources to build a bomb. They reject the Powers hypothesis.
Powers responds: "The reaction is a very sensitive, kind of touchy, prickly sort of reaction. The reason is not too hard to find. If Heisenberg refused to build a bomb for Hitler for moral reasons, then what were the Allied scientists' reasons for building a bomb that destroyed Hiroshima?"
Now let's look at one other explanation for Heisenberg's reluctance to build a bomb: He goofed.
"He was wrong in the physics of what it would take," Rudolph Peierls, an 85-year-old physicist who played a key role in the Manhattan Project, told us.
To make a bomb, you need not just your average lump of uranium (atomic weight 238) but rather an isotope of uranium (such as U-235) that can rapidly destabilize if bombarded with neutrons. But no one had ever separated large quantities of an isotope of a heavy element like uranium. And initially, physicists on both sides of the Atlantic assumed that you'd need tons of it to make a bomb. Getting that much fissionable uranium seemed utopian.
But Peierls and a colleague sat down and labored over the equations and - surprise! - discovered that you really didn't need that much of this special uranium to make something really devastating. "We figured out that the critical mass was not very large, not the tons that one would have guessed intuitively, but kilograms," he says. "We also realized that such a chain reaction would release an enormous amount of energy."
Heisenberg, on the other hand, never liked to mess around much with those nasty physics equations, says Peierls, his former student. Heisenberg was a genius but maybe a little lazy. As they say, the Devil is in the details, and this Devil is one that Heisenberg - and, mercifully, Hitler - never found.
Question: Why do creatures get more complicated as they evolve, instead of getting simpler?
Answer: It's not because "complicated" is better than "simpler." That's not true in animals any more than it's true in VCRs.
This has actually been the subject of much research and theorizing among biologists. No one can deny that life is more complicated now than it was a few eons ago. You just can't get around the fact that once upon a time there was nothing but scum, oozing along rocks and floating in sea water. Billions of years later, your average blob of scum has an accountant and a lawyer. So the question is, what drives this march toward complexity? Does evolution have some built-in bias for larger, brainier, more gadget-enhanced creatures?
Probably not. There's a (ahem) simpler explanation: Life mutates and evolves at random in both directions, toward simplicity and toward complexity. There's a bottom limit on how simple things can get - you can't get much more basic than scum - but there's no upper limit.
"If you look at the largest animals or the largest plants over geologic time, slowly the upper limits have been increasing," says John Bonner, a professor of biology at Princeton and author of "The Evolution of Complexity."
Some types of parasites have lost parts of their anatomy over time, he notes. Rotifers, a small invertebrate creature, apparently evolved from larger ancestors. And common duckweed has fewer cell types than the plants from which it is descended.
Bonner says, "There must be some instances where brains get smaller as well."
Maybe he should test those kids who watch too much "Barney" on TV.
Washington Post Writers Group