Emigres led U.S. to top in physics

Science: Many modern wonders owe their existence to the geniuses of the 1920s and '30s.

March 13, 2005|By FrankD. Roylance | By FrankD. Roylance,SUN STAFF

When Cornell University physicist and atomic-bomb theorist Hans A. Bethe died last week at age 98, many obituaries portrayed him as a "titan" - the last giant of a "golden age" of physics that flowered between the world wars.

Those years of experimenting and theorizing about the fundamental nature of matter and energy built the science that made possible construction of the first atomic bomb.

The same years, and the rise of Nazi power in Germany, also provided the fear and rationale for building the bomb, and the brilliant corps of scientists - many of them refugees from Hitler's race laws - who did the work for the United States instead of the Fuehrer.

But scientists and historians insist that physics in the 1920s and 1930s was far more than a workshop for the fathers (and mothers) of the post-war atomic "Balance of Terror" that gripped the world for 45 years. It was, discoveries with profound and lasting implications for society far bigger than the bomb, and seminal to modern materials science, engineering, computers, medicine, astronomy, astrophysics and cosmology.

And the brilliant young minds, many of whom fled fascism with this new knowledge, became the post-war teachers and role models for a new generation of scientists.

Their critical mass gave the United States pre-eminence in post-war physics, and foreshadowed what some would argue has become a new "golden age" in the field.

The list of modern wonders that owe their existence to the discoveries of the 1920s and '30s seems endless. Jonathan Bagger, chairman of physics and astronomy at the Johns Hopkins University, notes especially computer engineering and medicine, including the development of MRI machines and CAT scanners, the decoding of the human genome and nanotechnology.

"This is a golden age of physics for many reasons: for its interconnectedness with biological and materials science and indeed for the convergence of physics and astronomy - for answering some of the deepest questions humans can imagine," he says.

At the turn of the 20th century, scientists had only barely established that matter was composed of atoms. X-rays and radioactivity had been discovered, but they were not well understood.

"There were only about 1,000 physicists in the world in 1900; and if you asked people on the street what they did, they wouldn't have a clue," said Richard Rhodes, the Pulitzer Prizewinning author of The Making of the Atomic Bomb.

Until 1926, scientists labored under the mistaken idea that electrons circle their atomic nuclei as planets do their sun. This notion, born in the old world of Newtonian mechanics, worked fine to predict things on the scale of baseballs or even planets. But it broke down when scientists applied it to atoms.

Then, physicists including Austrian Erwin Schroedinger, German Werner Heisenberg and Briton Paul Dirac produced seminal work that proposed a new kind of physics called "quantum" mechanics. It was weird, but it worked.

At the scale of atoms, "one enters a region where probabilities and uncertainties become the language of physics," says Bagger.

Fundamental to this new physics is that the act of observing a system actually changes it. "You can't study an atom without jiggling it, and those jiggles change what it's doing," he says. But the message was clear: "If you wish to make new materials with new properties, you need to understand quantum mechanics."

Long-standing problems in physics began to tumble, and the ferment attracted some of the best minds in Europe and America. "Everybody jumped in," says Jeremy Bernstein, physics professor emeritus at Stevens Institute of Technology.

Many were drawn to Germany, which had quite intentionally made itself a scientific magnet. At the end of the 19th century it was racing to catch up to the other industrial powers. "They had to beef up their scientific research and development capabilities," says physicist Nina Byers of the University of California Los Angeles, who studied under atomic pioneer Enrico Fermi.

The Germans invested heavily in their universities, which became leading centers for physics and math. Germany in 1933 had more Nobel laureates than any other nation.

Brilliant students arrived from Germany, Austria, Hungary and elsewhere, among them Jews excluded from other academic fields.

In the 1930s, they discovered how the atom worked. They found it had a tiny nucleus with enormous amounts of energy locked up inside. Lise Mietner, an Austrian Jew working in Berlin, was a co-discoverer of nuclear fission - the theoretical key to atomic weapons and ultimately nuclear power plants, Byers said.

American physicist Robert Oppenheimer, who later would lead the Manhattan Project, earned his doctorate in Berlin. Bethe and Arnold Sommerfeld solved the great puzzle of the thermal properties of metals.

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