The triumph of unlikely heroes on a scientific quest

The Fly in the Cathedral: How a Group of Cambridge Scientists Won the International Race to Split the Atom

By Brian Cathcart. Farrar, Straus


and Giroux. 308 pages. $25.

This newspaper you're holding in your hands -- and your hands, for that matter -- are composed of atoms. For centuries, there was thought to be nothing smaller. The word itself derives from the Greek atomos, which means indivisible.


Then, in 1897, British physicist J.J. Thompson of Cambridge University made the startling discovery that atoms were not indivisible but composed of even tinier particles that he dubbed electrons. Scientific hell broke loose. Researchers around the world wondered: What other secrets is the atom hiding?

In The Fly in the Cathedral, Brian Cathcart recounts the fascinating early history of the physicists who pried loose these secrets. At the heart of his book is the mostly forgotten story of John Cockcroft and Ernest Walton, two young Cambridge University physicists who in 1932 won the global race to "split" the atom and thus penetrate its deepest, most enigmatic recess -- the atomic nucleus.

When Cockcroft and Walton began their quest in the late 1920s, the scientific picture of the atom remained fuzzy. Physicists knew that atoms consisted of negatively charged electrons that orbited a positively charged nucleus. They also knew there was lots of empty space. In fact, the nucleus was thought to be so puny compared with the vast nothingness of the atom that scientists at the time likened it to a fly in a cathedral.

That made the nucleus an elusive target. To make matters more complicated, the nucleus emits a potent electrical repulsive force. Penetrating this barrier, Cockcroft and Walton quickly realized, would require new technology: an atom smasher.

By the early 1930s, the two were one of five groups around the world trying to build a machine capable of bombarding an atomic nucleus with artificially accelerated particles. While they would ultimately win a Nobel Prize for their work in 1951, at the time the pair seemed the least likely to succeed.

The culture of Cambridge's Cavendish Laboratory where Cockcroft and Walton worked was strict: Experimentalists were expected to vacate their labs by 6:00 p.m. sharp, and scrounge for parts whenever possible. Most of Cockcroft and Walton's overseas competitors were used to working late into the night and were frequently better equipped. (Baltimore even plays a small -- but pivotal -- role in Cathcart's tale. At a time when radioactive material for experiments was expensive and scarce, Cavendish scientists were able to obtain significant amounts of radium from the old Howard A. Kelly Hospital on Eutaw Place through a British colleague at Johns Hopkins.)

Despite these seeming handicaps, by June 1932, Cockcroft and Walton had managed to cobble together a working particle accelerator out of vacuum tubes, high-voltage wire and modeling clay, and then use it to bombard lithium atoms with protons. Newspapers around the world reported the result: The pair had split the atom.

Today the experiment is credited with helping to raise the curtain on the Atomic Age. As Cathcart notes, it was also the first experiment to offer proof of Albert Einstein's iconic equation, E=mc2.


Cathcart, a journalist formerly with Reuters, does a fine job of explaining the science. Despite painstaking research, however, he ultimately has trouble bringing his central characters fully to life. Physics, then and now, is a field populated with colorful eccentrics. Cockcroft and Walton were two of the exceptions.

For that reason, Cathcart's book winds up being more of an intellectual adventure story than a human one. Yet, it's hard not to be captivated by the scientific challenges these early pioneers of atomic physics faced, chasing an object they could not see, stumbling blindly through the cathedral after their fly.

Michael Stroh covers science and medicine for The Sun.