Hans Bethe, a titan of physics and conscience of science, dies at age 98

ITHACA, N.Y. — Nobel laureate Hans Bethe, the last of the giants of
the golden age of 20th-century physics and the birth of modern atomic
theory, and one of science’s most universally admired figures, died
quietly yesterday evening at his home in Ithaca, N.Y. He was 98.

At his death, Bethe was emeritus professor of physics at Cornell
University, the institution he joined in 1935 after fleeing Nazi
Germany because his mother was Jewish. He was one of the most honored
members of the faculty in the university’s 140-year history for his
work in revolutionizing our perception of the real world. But he was
equally admired for his reputation for integrity, humility and
concern that made him the conscience of science.

In tribute, Jeffrey S. Lehman, president of Cornell, said; “The world
has lost one of the great pioneers of 20th century physics, and
Cornell has lost a beloved teacher, mentor and friend. In the breadth
of his insight, the rigor of his research, the depth of his social
conscience and the steadfastness of his commitment to Cornell, Hans
Bethe set the standard for engaged scientific citizenship that will
serve as a beacon for generations to come.”

Bethe’s fellow Nobel laureate, physicist Robert C. Richardson, who is
Cornell’s vice provost for research, said; “Hans Bethe was a giant of
20th century science. He has been revered by his Cornell colleagues.
He left profound and enduring marks of his intellectual leadership on
Cornell, the United States, and the entire world. Bethe had an
important influence upon me as a young faculty member when I arrived
at Cornell in 1966. He demonstrated a clarity of thought that I could
only hope to emulate some day.”

Bethe’s deep and abiding belief in science was unaffected by his work
on developing the first atomic bomb. “The intellectual achievements
of pure research are one of the things that make life worth living,”
he once said. Even when he had just witnessed the blinding flash from
the detonation of the first nuclear explosion at Trinity site in the
New Mexico desert on July 16, 1945, he professed only to a concern
about the atomic bomb’s functioning . “I am not a philosopher,” he
explained.

Yet he was deeply committed to humanitarian values, as shown in his
efforts to limit the use of nuclear weapons and his work to promote
the peaceful use of nuclear energy. “Science is always more unsolved
questions, and its great advantage is that you can prove something is
true or something is false. You can’t do that about human affairs —
most human things can be right from one point of view and wrong from
another,” he once said.

Eminent astrophysicist, Edwin E. Salpeter, who arrived at Cornell in
1949 to study under Bethe, said of his former mentor, “He brought
clarity to an amazing number of fields of science — especially in
astrophysics — where he had to work in the face of uncertainty.”

Despite the turmoil of history, Bethe remained committed to the idea
of physics as a thing of beauty leading to discovery and
understanding, a quest that he called “the spirit of physics.” It was
a spirit enunciated by his famously optimistic phrase “I can do
that,” always said in the face of opposition or adversity. Salpeter
noted that Bethe’s optimism sprang from knowing how to use the
minimum mathematical complexity compatible with each problem he
faced. “In his hands, approximations were not a loss of elegance but
a device to bring out the basic simplicity and beauty of each field,”
he said.

During World War II Bethe was a key figure in the building of the
first atomic bomb as head of the theoretical physics division at Los
Alamos. Bethe would later recall how “two elder statesmen” told J.
Robert Oppenheimer, director of the Manhattan Project, ” ‘Look here,
you can’t run the theoretical division if you run the laboratory at
the same time, and there has to be a theoretical division. It has to
be organized. And so the obvious person to put in charge of the
theoretical division is Bethe.’ ”

But after World War II Bethe became a persistent champion of nuclear
arms control, helping to persuade the White House to ban atmospheric
nuclear tests in 1963 and antiballistic missile systems in 1972. And
he stood firm in his opposition to President Ronald Reagan’s
Strategic Defense Initiative, the missile defense system known as
Star Wars. “The Star Wars system involved impossible tasks to make
lasers of unheard of power [and then] to deploy them on satellites in
space,” he argued.

Bethe also was a deeply committed, even sensitive, teacher, and from
1945 until his retirement from active teaching in 1975 he trained and
inspired a large number of graduate students. One of them, Freeman
Dyson of the Institute for Advanced Study at Princeton, once noted
that Bethe would often continue classes over lunch “and that’s where
most of the teaching was really done.”

His presence at Cornell was a magnet that attracted a world-class
faculty to the university’s physics department. During the 20 years
following the war he became more involved in what he called
“political physics,” an attempt to educate the public and
politicians about the consequences of the existence of nuclear
weapons. He was on the President’s Scientific Advisory Committee
which gave advice to President Eisenhower and, later, to Presidents
Kennedy and Johnson on such matters as ways to limit nuclear
proliferation and further development of atomic weapons.

Bethe was truly indefatigable. In his 90s, with his left arm and
shoulder wasted by a degenerative muscle disease, he continued to
arrive regularly at his office at the Newman Laboratory on the
Cornell campus although, he admitted, “not every day do I find
anything interesting.” Every day began with a 45-minute hot bath,
because, he said, “You sleep, and things get somewhat unscrambled in
your mind; then in the bath, I can become conscious of that.” And he
always carried with him his old slide rule on which he could with
ease perform calculations to the sixth power.

Hans Albrecht Bethe was born July 2, 1906, in Strasbourg, now in
France but then part of Germany. He showed an early genius as a
mathematician, studying physics at the University of Frankfurt and
doing research in theoretical physics at the University of Munich,
where he was a student of Arnold Sommerfeld, the teacher of Wolfgang
Pauli and Werner Heisenberg, and where he received his doctorate in
1928. In 1930 and 1931 he received fellowships, first to the
University of Cambridge and then to the Institute of Physics in Rome,
where he worked with Enrico Fermi. He taught at Frankfurt and Munich.
At the Technical University of Stuttgart he was assistant to Paul
Ewald, professor of theoretical physics, who would become his
father-in-law a decade later when Bethe married Rose Ewald, then a
student at Smith College in Massachusetts, and who graduated from
Cornell in 1941.

Bethe’s father, a professor of physiology, was a Protestant, but his
mother was Jewish. This brought him into conflict with Nazi race laws
after Hitler came to power, and Bethe was dismissed from his post at
the University of Tubingen. He left Germany, going first to England,
then to the United States and Cornell in 1935.

Bethe later said of his arrival at Cornell; “I came to America
expecting to be among strangers. I came home to Ithaca.” And he
regarded it as home for the next 70 years.

It was Bethe who propelled Cornell’s physics department into the top
rank. And it was at Cornell during the late 1930s that he wrote his
famous reviews of nuclear physics and, in 1938, published his seminal
paper on the theory of energy production in stars that explained how
the sun shines. The work was to win him the Nobel Prize in 1967.

During his years as a physicist he published papers in every decade
from the 1920s through the 2000s. In 1995 Bethe’s colleagues,
students and friends marked his 60 years at Cornell with a two-day
tribute to his life and work. “If you know his work,” said John
Bahcall of the Institute for Advanced Study, delivering his own
appreciation, “you might be inclined to think he is really several
people, all of whom are engaged in a conspiracy to sign their work
with the same name.”

After World War II Bethe brought some of the most outstanding young
physicists at Los Alamos to Cornell, among them Richard Feynman and
Robert Wilson. Under their leadership Cornell became a world center
for high energy elementary particle physics. Bethe and Feynman played
a central role in developing quantum electrodynamics, work for which
Feynman shared the Nobel Prize in 1965. During this period Bethe also
produced the first major paper on the theory of order-disorder
transitions in alloys.

After his retirement from teaching he devoted much of his time to
astrophysics, and wrote papers with Bahcall trying to explain why the
sun produced fewer particles called neutrinos than predicted by
Bethe’s theory of stellar energy production. And at the age of 83 he
apprenticed himself to Gerald E. Brown of the State University of New
York at Stony Brook in order to learn lattice gauge theory. The
theory, which predicts how nuclear matter is transformed at extremely
high temperatures into a plasma of particles called quarks and
gluons, is one of the most challenging in all of physics. “I’m
interested in learning new things,” Bethe explained. The two
scientists went on to publish numerous papers together on
astrophysics.

He was deeply in love with the mountains, spending at least two or
three weeks every summer walking in the U.S. Rockies or the Swiss
Alps. He was also a stamp collector, a hobby he took up in his teens
and resumed in his late 40s and continued until his death. “It was
the one place in the world where all countries sat together
peacefully,” he said. He also was passionately interested in history.

In addition to his wife, he is survived by two children, Henry, of
Ithaca, and Monica, who lives near Kyoto, Japan, and three
grandchildren.

The web version of this release, with links to photos, may be found at
http://www.news.cornell.edu/releases/March05/Betheobit.deb.html