Broken symmetry

The 87-year-old American physicist Yoichiro Nambu, born in Japan, has been awarded half of the 2008 Nobel Prize in Physics "for the discovery of the mechanism of spontaneous broken symmetry in subatomic physics". Today, he's a professor emeritus at the University of Chicago.

Nambu's mind-boggling work deals with a mysterious concept, spontaneous symmetry breaking, which can nevertheless be described in a simple context. Symmetry breaking? Let me talk rather about egg breaking...

Real-world eggs are more or less symmetric with respect to an axis that goes through the middle of the egg from the blunt end to the pointed end (where the adjectives "blunt" and "pointed" are purely relative). Here's an interesting experiment that you can perform in front of a friend... not necessarily a good friend. Tell him/her that you're going to hold an egg in front of you, fixed between the palms of your two outstretched hands: your left palm pushing in on the blunt end, and your right palm on the pointed end. Next, you are going to squeeze the egg between your palms, harder and harder, until something happens... Roughly speaking, the egg will explode in one of four general directions. If you friend is unlucky, he/she will get sprayed with fallout. Otherwise, you might get hit in the face with your scrambled egg, or the fragments might fly either upwards or downwards. The interesting question is: Why would an essentially symmetrical egg "choose" to explode in one of these four general directions rather than in another?

In a real-world experimental situation, it's easy to imagine obvious reasons why an egg-squasher might succeed in obtaining one outcome rather than another. To put egg on your friend's face, for example, you would only need to wriggle your palms around in such a way that they channeled the eggy projectile away from you. But let's be theoretical, and imagine a perfectly symmetrical egg held between ideally innocent hands in a weightless environment. It would still explode, and the fragments would still fly out in one of the four general directions. In other words, within a perfectly symmetrical context, a disparity has suddenly appeared. How? Why? What caused the unbiased egg, brought up—like a member of British royalty—to be impartial under all circumstances, to "choose" one of these four directions?

An explanation of Yoichiro Nambu's answer to these questions would lie far beyond the scope of this humble blog and the talents of this ever-curious but unpretentious blogger. Let me simply say that, in the weird world of quantum physics and string theory, inhabited by a mysterious creature known as the Higgs boson, all sorts of unthinkable things can indeed arise spontaneously. Even nothingness can suddenly be transformed into somethingness. Astonishing, no?