Szilard first proposed the cyclotron and electron microscope

Person: Leo Szilard
Lived: 1898–1964
Field: Nuclear physics
From: Hungarian-American

The story

Leo Szilard arrived in Berlin from Budapest at the end of 1919. He studied engineering, grew bored, and switched to physics at Friedrich Wilhelm University, attending lectures by Albert Einstein, Max Planck, Walther Nernst and Max von Laue. After earning his doctorate in 1922 he became von Laue's assistant and, in 1927, a lecturer. Throughout his Berlin years he poured out ideas for new technical inventions, often far ahead of their time, and he was fascinated by how electric and magnetic fields could steer beams of particles.

In 1928 he submitted a patent application for the linear accelerator, not knowing of earlier work on the same idea by Gustav Ising and Rolf Widerøe. In late 1928 and early 1929 he filed applications in Germany for a circular accelerator, the cyclotron, and for the betatron. In these applications he became the first person to discuss the resonance condition that makes a circular accelerator work.

He also coined the concept of the electron microscope and submitted the earliest known patent application for one, in 1928. The physicist Dennis Gabor, a fellow Hungarian in Berlin, later recalled that Szilard tried that year to persuade him to build one.

Szilard never built these machines or published the ideas in scientific journals, so credit often went to others. Ernest Lawrence won the Nobel Prize in 1939 for the cyclotron, and Ernst Ruska received the 1986 Nobel Prize for the electron microscope. Szilard himself never received a Nobel Prize.

His patents nonetheless show how clearly he foresaw the tools that would shape twentieth-century science. Particle accelerators became central to nuclear and particle physics, and linear accelerators are used in hospitals to deliver radiation therapy for cancer. Electron microscopes allowed scientists to see structures far too small for ordinary light microscopes, from viruses to the fine detail of cells and materials.

The same inventive streak ran through his whole career, from his work with Einstein on a refrigerator with no moving parts to the nuclear reactor he later patented with Enrico Fermi.

Why it matters

Cyclotrons, linear accelerators and electron microscopes became indispensable to physics, medicine and biology, including cancer radiotherapy and imaging of viruses.

About Leo Szilard

Physicist who conceived the nuclear chain reaction in 1933, drafted Einstein’s letter to Roosevelt, co-built the first reactor, then campaigned for the rest of his life against nuclear war.

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Leo Szilard

1898–1964 · Nuclear physics

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