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The Question
(Submitted November 24, 1997)
Who was the first person to discover a black hole and what was the date?
The Answer
Black holes cannot be observed directly and therefore cannot be 'discovered'.
However, as we explain at our website, the indirect evidence for two kinds of
black hole is now overwhelming - those of a few solar masses produced by
supernovae and much larger ones at the center of some galaxies.
The existence of bodies with gravitational fields strong enough to allow
nothing to escape has been a topic of speculation for hundreds of years.
Einstein's general theory of relativity (published in 1916) predicts just
the kinds of object we are now inferring.
Perhaps the first object to be generally recognized as a black hole is the
X-ray binary star Cygnus X-1. Its effect on its companion star suggested
as early as 1971 that it must be a compact object with a mass too high for
it to be a neutron star. (That was 2 years after the American astronomer
John Wheeler coined the term 'black hole').
Paul Butterworth
for the Ask a High-Energy Astronomer Team
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