By Tamara Homan
 |
Dr. Alexei Filippenko of UC Berkeley answers questions after his MIRA Lecture in September 2001 the recently discovered Acceleration of the Universe. |
As long as humankind has been walking around with these large brains capable of complex thought, we have been asking where the universe came from, and how it will end. Leave it to cosmologist Alex Filippenko, Ph.D., to answer those questions with a lucid humor and catchy examples. Voted the best teacher of the year by the students of the University of California Berkeley campus, he likens the expanding universe to an immense loaf of raisin bread—with the Milky Way and all other galaxies as the raisins. Then it becomes clear why more distant galaxies move away from us faster than closer galaxies. Because there's more dough between us, of course! As the dough rises and the distance from "here" to "there" doubles and then doubles again, we can only speculate how many toasters it would take to brown all of that bread. Pass the butter, please, Dr. F.
How far away is that 100-watt light bulb? That depends on how bright it looks, of course: brighter when it's closer, and fainter when it's not so close. If we know its absolute brightness (that it is a 100-watt bulb, not 25), we can calculate how far away it is based on how bright it looks to us (its apparent brightness). Much observational cosmology has involved the search for such "standard candles."
Dr. Filippenko and other researchers use their own astronomical "100-watt bulbs," for comparison: supernovae. Those immensely powerful objects come in handy, or at least type Ia's (which result when white dwarf stars explode), because we know about how bright they are. Comparing this known quantity in nearby galaxies to supernovae in more distant galaxies lets astronomers estimate how far away they are.
This research points to a unexpected conclusion: that the rate of expansion of the universe is actually accelerating. This acceleration, originally predicted by Albert Einstein nearly a century ago (and later recanted by him) must be caused by a previously unknown energy, originating in the interstellar vacuum, which is causing the acceleration. So startling is this finding, and so difficult to explain with our present understanding of physics, that Science magazine deemed it the scientific breakthrough of 1998.
For more information about the red shift, supernovae, and cosmology, visit the Lawrence Berkeley National Lab's Website at
http://www-supernova.lbl.gov/ .
| Winter 2002 Contents | Newsletter Index | Mira Home Page |
Last updated 2/17/02 DMC