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Big Bang
“The most incomprehensible
thing about the universe is that it is comprehensible.”
Albert Einstein
I
decided to write a book about the Big Bang theory of the
universe because it is one of the pinnacles of human
achievement. I wanted people to understand the theory and to
appreciate why cosmologists are confident that it is an
accurate description of the origin and history of the
universe.
The book is essentially the story of the Big Bang theory. Like
any good tale, the discovery and proof of the Big Bang theory
has more than its fair share of curious incidents and peculiar
characters. |
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The story begins with the theoretical foundations laid by
Einstein and his General Theory of Relativity. But it was
Georges Lemaître,
a Catholic priest from Belgium, who proposed the idea of a universe born at a single instant in
the past - "a day without a yesterday" - and expanding
outwards from that moment.
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Henrietta Leavitt
Inventor of the cosmic yardstick.
(Courtesy of Harvard
College Observatory)
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While theorists developed this hypothesis, it was up to the
observational astronomers to test the theory against reality.
Unfortunately, they were having serious problems with
measuring reality. Even measuring distances across the
universe had proved problematic. In particular, nobody could
measure the distances to the galaxies. Henrietta Leavitt was
the woman who rescued the situation. Working as a 'computer'
in the days when few women could pursue a career in science,
she was employed to measure and analyse photographs of the
stars in painstaking detail. With a great leap of intuition,
she showed that Cepheid variable stars, which vary
periodically in brightness, could be used to measure distances
across the universe. She realised that the rate of variation
of a Cepheid star gave a strong indication of its actual
brightness, which could then be compared with its |
apparent
brightness as seen from Earth, which then indicated the
distance to the star. When Cepheid variable stars were found
in distant galaxies, it became possible to measure the
distance to the galaxies.
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With a cosmic yardstick for measuring the distance to the
galaxies, Edwin Hubble made a remarkable discovery. Although
born an American, Hubble had fallen for the charms of the
English aristocracy and groomed himself into the quintessential
English gentleman while studying in
Oxford.
Using some of the biggest telescopes ever built - marvels of
engineering in their own right - he found that all the galaxies
were racing apart from each other. Not only that, but the
further away a galaxy was, the faster it was moving.
Running the clock backwards led to a disturbing conclusion.
There must have been an instant in the distant past - that day
without a yesterday - when |
Herman, Gamow and Alpher,
who predicted an echo
from the Big Bang.
(Courtesy of Ralph Alpher)
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everything in the universe exploded into being out of a single
point in space. The evidence was pointing towards a Big Bang. A
moment of creation.
But the theory was controversial. The scientific establishment
believed in an eternal universe, and many cosmologists were
reluctant to accept a theory that smacked of |
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Fred Hoyle
who opposed the Big Bang theory and
developed the Steady State theory
(Courtesy of St John's College Library, Cambridge)
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divine creation. Hence, Fred Hoyle proposed an alternative
Steady State model in which
the universe was both expanding and eternal. However, even
though Hoyle was an opponent of the Big Bang theory, it was he
who christened the theory, referring to it
disdainfully in a radio broadcast as "this 'Big Bang' idea".
The name stuck, and so did Hoyle's opposition to the theory.
The
stage was set for a major battle between the two camps – Big
Bang versus Steady State. It would take the rest of the
twentieth century to resolve the conflict, with both sides
desperately searching for evidence to shore up their own theory
and crush the opposition. The battle for cosmic truth would
involve politics, religion, bitter disputes, nuclear physics, satellites, telescopes, a supposed echo from the Big Bang,
and remarkable serendipity, resulting in one of the greatest
adventures in the history of science. |
To find out what the critics think, please visit
the Big Bang Reviews page.
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