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Oppenheimer’s brief advance into astrophysics began with
a 1938 paper about neutron stars, which continued in a 1939
installment that further incorporated the principles of Einstein’s
general theory of relativity. He then published a third paper on
black holes on September 1st, 1939—but at the time, it was
scarcely noticed because this was the very day Germany invaded
Poland, launching World War II. Oppenheimer never wrote on
the topic again.
Even if it hadn’t been overshadowed by war,
Oppenheimer’s work on neutron stars and black holes “was not
understood to be terribly significant at the time,” says Cathryn
Carson, a historian of science at the University of California,
Berkeley.
Each paper was written with a different member of the
swarm of graduate students that Oppenheimer carefully
cultivated. These protégés facilitated his ability to jump between
research topics—and ultimately, helped him develop some of his
most important contributions to physics.
Oppenheimer’s climactic third paper, written with his
student Hartland Snyder, explores the implications of general
relativity on the universe’s most massive stars. Although the
physicists needed to include some assumptions to simplify the
question, they determined that a large enough star would
gravitationally collapse indefinitely—and within a finite amount
of time, meaning that the objects we now know as black holes
could exist.
Internet: <scientificamerican.com> (adapted)