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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:
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. 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. 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. 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. reports
that dark matter maps reveal that galaxies are enveloped by giant clouds of
dark matter. 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). explains
that if dark matter strikes a super-cooled germanium crystal, the collision
produces a minute amount of heat, which can be detected. 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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