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NOVA scienceNOW: Dark Matter
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Program Overview
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This segment describes how scientists are trying to detect dark
matter, a mysterious form of matter that exerts a gravitational
force and seems to hold different bodies in the universe together.
This NOVA scienceNOW segment:
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explains why physicists think dark matter exists—stars
within galaxies and galaxies within galaxy clusters move faster
than expected and, rather than flying apart, they stay in orbit
together. However, there is not enough visible matter present to
account for the gravitational pull required to hold these units
together. Hence, if the laws of gravity are right, there must be
an elusive substance (i.e., dark matter) responsible for the
necessary gravitational force.
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describes dark matter by what it is not, rather than what it
is—it's invisible; doesn't glow; isn't composed of atoms;
and doesn't create electric or magnetic fields.
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suggests that dark matter may be made of a yet-to-be-identified
particle, and that where there is ordinary matter, there is dark
matter.
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theorizes that after the Big Bang, dark matter acted like glue,
pulling stars together to form galaxies, and that, without dark
matter, galaxies would probably not have formed.
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reports that dark matter maps reveal that galaxies are enveloped
by giant clouds of dark matter.
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describes a super-sensitive detector designed to "catch" dark
matter particles. It is made of germanium, a superconducting
crystal, that is kept at 50 thousandths of a degree above
absolute zero (460 degrees below zero Fahrenheit).
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explains that if dark matter strikes a super-cooled germanium
crystal, the collision produces a minute amount of heat, which
can be detected.
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notes that because the detector is so sensitive, many things can
set it off. Therefore it is located in an abandoned mine
one-half mile underground.
Taping Rights: Can be used up to one year after the program
is taped off the air.
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