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Echoes
of the Big Bang
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Penzias and Wilson stumbled upon
our best evidence for the Big Bang Theory |
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In
1964, two technicians at Bell Laboratories were conducting
routine radio astronomy experiments. But Arno Penzias and
Robert Wilson had a problem. Their radio antenna in Holmdel,
New Jersey seemed to be acting up. The scientists could not
eliminate a constant low-level interference signal.
Was
it the pigeons nesting in the receiving dish? Was it nearby
New York City? With elbow grease and trial and error, Penzias
and Wilson determined the answer to both questions was "no."
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Penzias and Wilson were already acquainted with the
Big Bang theory, which held that the Universe was born
out of an enormous explosion
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The
physicists were already acquainted with the Big Bang theory,
which held that the Universe was born out of an enormous explosion
some 15 billion years ago. Edwin Hubble's 1929 observation
that galaxies rush away from each other like debris from a
bomb was one of the first clues that the Universe had a violent
beginning. By 1948, George Gamow hypothesized that such an
explosion would have emitted huge amounts of radiation, the
low-level remnants of which were likely still present today.
The equipment of Gamow's day, however, was not sensitive enough
to detect these ancient echoes. By the mid- 1960's, though,
Princeton researcher Robert Dicke was working on a receiver
designed precisely for the task.
When
Pezias and Wilson heard of Dicke's work, they realized the
interference they had tried so hard to eliminate was the same
signal Dicke was seeking, what cosmologists call the primordial
background radiation. In 1978, Penzias and Wilson won the
Nobel Prize for Physics for their accidental discovery of
the best evidence for the Big Bang that we have to date.
Pulsating
Stars
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| Graduate
student Jocelyn Bell discovered a whole new class of star
in 1968 |
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Just
three years later, another set of radio signals puzzled Jocelyn
Bell, a graduate student at Cambridge University in England.
Bell's research turned up regularly spaced high-energy blasts.
After eliminating the possibility that the signal was terrestrial
interference, Bell pondered another explanation. Had the signal
been sent by an alien civilization? The possibility led Bell
to name the anomaly "LGM," for "little green men."
But she soon discovered similar periodic blasts of radiation
in other parts of the sky, convincing her that the signals
originated from a natural source. As it turned out, Bell had
discovered a previously unknown type of star which she later
named "pulsars," a contraction of "pulsating stars."
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Had the signal been sent by an alien civilization?
Bell named the anomaly "LGM," for "little
green men."
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Since
1968, astronomers have detected more than 1000 pulsars. Though
their exact nature is not well understood, current thinking
holds that a pulsar is a small, dense, fast-spinning remnant
of a super nova - the explosion that occurs when a star burns
out. Her remarkable observation gave astronomers valuable
insight into the life stories of stars, and earned her graduate
advisor, Dr. Anthony Hewish, the 1974 Nobel Prize in Physics.
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Photos:Bell
Labs, Lucent Technologies, Inc. ; NASA
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