'Beyond Uncertainty' by David C. Cassidy
Reviewed By Sara Lippincott
In June 1925, while recuperating from hay fever on the pollen-free island of Helgoland in the North Sea, Werner Heisenberg conceived of the first mechanics for quantum theory -- a way to actually do it. He was 23 years old. Physicists are said to do their best work when they are barely out of their teens; this is a signal example. Until Heisenberg's breakthrough -- which soon came to be called matrix mechanics, because it manipulated matrices, or lattices, of numbers, with weird but satisfying results -- there was no real connection between Niels Bohr's semiclassical picture of quantum physics and the ground.
Two years later, Heisenberg came up with his now-famous (and widely co-opted by philosophers and playwrights) uncertainty principle, which in essence says you can't simultaneously pin down the location and momentum of a subatomic particle. It is one of the pillars of the so-called Copenhagen interpretation of quantum theory, which upended classical Newtonian physics and revealed matter and energy as fundamentally discontinuous and unpredictable. End of physics lecture.
I have a photograph of Heisenberg on the wall of my office, taken shortly before his Helgoland epiphany. It's up there because for some reason it makes me feel good. Wearing a sweater that his mom might have knitted, he's smiling radiantly at the camera. The same photo is reproduced in "Beyond Uncertainty," David C. Cassidy's new biography of this controversial 20th century giant, in which he observes that in "snapshots of Heisenberg as a young man, he always appears radiant, confident, alert, and pleasant."
References to his subject's radiance and good nature even in the darker days of his later life occur throughout the book. It is also an excellent piece of science writing; in a chapter titled "Determining Uncertainty," Cassidy gives the clearest explanation I have ever come across of the mind-boggling arcana of quantum physics.