On Polonium

I’ve been doing some research into polonium for an article to appear in a forthcoming issue of Popular Science. Polonium has been in the headlines for the past few months, since it was slipped into the tea of former Russian spy Alexander Litvinenko and killed him. Nuclear physicists have a nickname for polonium. They call it the terminator, not because of its efficacy as a poison, but because of its place in the Periodic Table at the end point of the slow neutron capture process (s-process).

Elements form in stars when a nucleus grabs a loose neutron and converts it into a proton, thereby increasing its atomic weight and pushing it one step up the Periodic Table. But polonium is highly unstable. It decays so fast that too little of it is around long enough for the s-process (which is very slow, about one neutron capture every 30 years or so) to take place. As a result, all of the elements higher than polonium in the Periodic Table form through the rapid neutron capture process (r-process), which occurs once every .1 of a second—but only in supernovas. The difference between making an element with the s- and the r-process is kind of like the difference between cooking an egg by dropping it into boiling water and dropping it into an active volcano.

Cooking is an excellent metaphor for how elements are made. The elemental broth of stars boils away over billions and billions of years, and eventually all the constituents of matter are prepared, laid out like some cosmic smorgasbord from which the ingredients of every single thing are selected. Polonium is a highly energetic substance. Alpha particles, a form of radiation, are crashing around inside it with such force that the material takes on a life of its own. If left in an open container (a teacup, for example), it will quickly scale the sides of the receptacle and permeate the entire room, attaching itself to everything—and everyone—it touches. Just like the smell of some particularly pungent dish will cling to your clothes, your breath long after the meal itself has been consumed. Speaking of cooking and stars, there is an aphorism by French gourmand Jean–Anthelme Brillat–Savarin that refers to both of these natural and man-made wonders:

The discovery of a new dish does more for the happiness of mankind than the discovery of a star.