Hour One:Dark Side of the Universe

Astronomers and cosmologists are feeling the power of the dark side...Whereis all the stuff in the universe? And what's making it move? Those aretwo of the thorniest problems plaguing cosmologists, but now they havea couple of new theories to work with.

Back in the 1930's, Fritz Zwicky realized thatthe velocity of some huge galaxies was too great for the apparent amountof matter in them. Without some hidden, invisible mass, there shouldn'tbe enough gravity to hold the galaxies together. Some 40 years later, VeraRubin and others figured out that the way that rotating galaxies behavealso points to a large unseen pool of matter in the universe.

Not Dark: Supernova 1987a. Hubble Heritage Team.

This mysterious stuff has come to be called "dark matter' -- and it appearsto make up the vast majority of the matter in the universe. Many astronomersand cosmologists are trying to figure out what the "dark matter" actuallyis, because knowing  the answer could help explain many aspects ofthe cosmos -- from the workings of the Big Bang to the ultimate fate ofthe universe. A zoo of exotic things, from WIMPS (weakly interacting massiveparticles) to MACHOs (massive compact halo objects) have been suggestedas possibilities.

At the same time, there also seem to be forces of "dark energy" at work-- forces that are hard to reconcile with our present understanding ofthe universe. Two years ago, scientists announced that the universe's expansionappeared to be accelerating outwards, when, according to all concerned,the expansion should have been slowing down. The inward pull of gravityon all the objects in the universe seemed to be balanced out by some unseenforce driving the expansion. Now, some cosmologists are suggesting thatthe acceleration may be an effect coming from outside our universe -- aparallel universe. Their reasoning involves superstring theory, which representsall matter as being made up of tiny wriggling "strings" moving in 10 dimensions. 

On this hour of Science Friday, we'll shine some light search for darkmatter and try to unravel the superstring tangle (just a bit.) Join usfor the discussion, and call in with your questions and comments at 1-800-989-8255.
 

Listen to this program in RealAudio!

Guests:

Michael Turner
Staff Scientist
FermiNational Accelerator Laboratory
Chair and Professor, Departmentof Astronomy and Astrophysics
University of Chicago
Chicago, Illinois

Bernard Sadoulet
Professor, Physics
Director, Centerfor Particle Astrophysics
UCBerkeley
Berkeley, California

Andreas Albrecht
Professor, Physics
Universityof California, Davis
Davis, California

Books/Articles Discussed:

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Related Links:
Physics Focus: Quintessence
DarkMatter, Cosmology, and Large-Scale Structure of the Universe
Chandra- About Xray Astro - Dark Matter
DarkMatter
DarkMatter
DarkMatter 2000 Conference
March6, 1998, Hour 1, First Half: A Swiftly Expanding Universe
May1, 1998, Hour 1, Second Half: Missing Energy?
OnlineNewsHour: Expanding Universe -- February 27,1998

  

This segment produced by:

Karin Vergoth
Web producer:
Charles Bergquist