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| Inflationary Cosmology: Is Our Universe Part of a Multiverse? |
| Professor Alan Guth |
| Thursday, Oct 13, 2011 at 8:00 PM |
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| I will begin by explaining how inflation works, emphasizing how
inflation can account for the properties of the cosmic background
radiation, which we view as the afterglow of the big bang
explosion. This radiation is incredibly uniform, but also has a
pattern of faint ripples that are attributed by inflation to the
probabilistic behavior of quantum theory. An interesting feature
of inflation is that almost all versions of it lead to eternal
inflation: once inflation starts, it goes on forever, producing a
"multiverse" of "pocket universes," one of which would be our
universe. I will then turn to the biggest outstanding mystery in
cosmology: the "cosmological constant," which is equivalent to
attributing a nonzero energy density to the vacuum (i.e., to
empty space). Physicists are not surprised that the vacuum
energy density is nonzero, but are at a loss to explain why it is
so small --- theoretical estimates are many orders of magnitude
larger. I will explain how the multiverse might help to shed
light on this problem.
ALAN H. GUTH is the Victor F. Weisskopf Professor of Physics
and a Margaret MacVicar Faculty Fellow at the Massachusetts
Institute of Technology. Trained in particle theory at MIT,
Guth held postdoc positions at Princeton, Columbia, Cornell,
and SLAC before returning to MIT as a faculty member in
1980. His work in cosmology began at Cornell, when Henry
Tye persuaded him to study the production of magnetic
monopoles in the early universe. Using standard
assumptions, they found that far too many would be produced.
Continuing this work at SLAC, Guth discovered that the
magnetic monopole glut could be avoided by a new proposal
which he called the inflationary universe. Guth has been
elected to the National Academy of Sciences and the American
Academy of Arts and Sciences, and had been awarded the
Franklin Medal for Physics of the Franklin Institute, the
Dirac Prize of the International Center for Theoretical
Physics, the Cosmology Prize of the Peter Gruber Foundation,
and the Newton Prize of the Institute of Physics (UK).
Guth is still busy exploring the consequences of
inflation. He has also written a popular-level book called
"The Inflationary Universe: The Quest for a New Theory of
Cosmic Origins" (Addison-Wesley/Perseus Books, 1997).
Please join us for a pre-meeting dinner discussion at Changsho, 1712 Mass Ave, Cambridge, MA at 6:00pm before the meeting. |
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