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Friday > Archives
> 2000
> October
> October 6, 2000:
Hour One: Astronomy Update
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Conventional wisdom in astronomy says that 90 percent of the
universe is made up of "dark matter," a mysterious material
that emits no radiation, and so has not yet been seen. The presence
of this dark matter is needed to make the observations of the
way that the universe behaves agree with other factors that can
be measured -- in other words, to make all the numbers come out
even.
But what if that assumption -- that there is dark matter -- is
wrong?
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NOT dark matter. Probably. (Hubble
Heritage Team, StSci/Aura/NASA)
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A controversial theory called modified Newtonian dynamics (MOND) explains
the behavior of the universe by saying that the pull of gravity varies
depending on the density of matter, centripetal acceleration, and other
factors. Adherents of this theory, which is much reviled in the cosmological
community, say that it allows them to explain astronomical data without
nearly so many fudge factors as the existence of "dark matter"
would require. We'll talk about MOND, and arguments for and against
it -- and about how to look at the universe in different ways.
The sigma Orionis star cluster, the location
of 18 possible new extrasolar planets.
(image courtesy Science)
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We'll also talk about a new paper that may throw a wrench into
conventional explanations of planetary formation.
An international team of researchers reports this week in the
journal Science that they have found 18 planet-like objects
in a region of the Orion constellation. What is unusual about
these possible extrasolar planets, however, is that they are drifting
free, without a central star. Conventional wisdom says that planets
are formed as gas and dust swirling around a central star gradually
clumps together over millions of years.
We'll talk to one of the authors of the new study about how the
possible planets were located, and what the discovery may mean.
Stretching the boundaries of our understanding of the universe
on this hour of Science Friday. Call in with your questions and
comments - our number is 1-800-989-8255.
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Guests:
Eduardo Martin
Assistant Professor
Institute for Astronomy
University of Hawaii
Honolulu, Hawaii
Stacy McGaugh
Assistant Professor
Department of Astronomy
University of Maryland
College Park, Maryland
Don Goldsmith
Author
"The Runaway Universe : The Race to Discover the Future of the
Cosmos"
Berkeley, California
Books/Articles Discussed:
Related Links:
Windows
on the Universe: Dark Matter
NASA:
Dark Matter
Extrasolar
Planets
Extrasolar Planets
Encyclopedia
A Brief History
of Astronomy
Dark Matter or Different
Gravity?
Produced By: Charles Bergquist
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