Orrell applied the “Page 99 Test” to his new book, Truth or Beauty: Science and the Quest for Order, and reported the following:
Truth or Beauty is about the role of aesthetics in science. The book is divided into three sections – Infatuation, Complication, and Maturation – which chart the relationship between science and beauty throughout history. Page 99 is found in the first chapter of Complication: the topic is relativity and quantum theory, and this page is discussing the period a hundred years ago when Niels Bohr and other scientists were developing a new model of the atom.Learn more about the book and author at David Orrell's website.
The classical model of the atom had electrons orbiting a nucleus like planets in a solar system. While this picture had an appealing simplicity, physicists knew that it couldn’t be right: according to theory, an orbiting electron should emit electromagnetic radiation, lose energy, and collapse into the nucleus, all in less than a billionth of a second. Bohr got around this problem by asserting that electrons were restricted to certain energy levels – described by so-called quantum numbers – and could only switch between them in discrete hops, emitting a pulse of electromagnetic radiation (light) as they did.
A triumph of Bohr’s model was that it explained in a stroke how atoms of a particular substance (for example, the neon found in neon lights) would emit radiation in certain discrete, characteristic wavelengths, known as spectral lines. As in a musical instrument, where sound wavelength corresponds to the note heard, each element produced a unique mix of tones. This was reminiscent of the Pythagoreans’ idea of the music of the spheres, a music which they believed permeated the cosmos but only Pythagoras could hear (ordinary mortals having tuned it out). On page 99 I quote the physicist Arnold Sommerfeld: “What we are listening to nowadays in the language of spectra, is a genuine atomic music of the spheres, a richly proportioned symphony, an order and harmony emerging out of diversity.”
Unfortunately, further experiments showed that the predicted spectral lines did not quite match observation. More quantum numbers had to be added to the model, a development which (the page continues) “seemed like a step in the wrong direction. The model had so many parameters that it had lost any pretense of simplicity or elegance.”
Page 99 therefore captures the fundamental tension which runs through the book, between the aesthetic desire for simplicity and beauty, and the contingencies of messy reality. The same conflict is found today between the proponents of supersymmetric string theory (a more modern attempt to link physics with vibrating strings) and its critics who describe it as motivated more by aesthetics than by experimental evidence.