[Colloquium] 10/17 TTIC Colloquium: Michael Douglas, Stony Brook University

[Mary Marre via Colloquium]

When:     Monday, October 17th at 11:00 a.m.

Where:    TTIC, 6045 S. Kenwood Avenue, 5th Floor, Room 526

Who:       Michael Douglas, Stony Brook University

Title:       Computational Complexity of Cosmology in String Theory

Abstract:
Superstring theory is the most widely accepted candidate for a fundamental
theory of physics, unifying
gravity with the other forces of nature.  It predicts that our universe has
six additional dimensions of space,
unobserved because they form a very small compact manifold.  There are then
many possibilities for the
laws of physics as seen in four dimensions, which depend on the choice of
topology, geometry and
additional structures of this manifold.  The vast majority of these
choices not only lead to physics which is in disagreement
with what we see, they are incompatible with the existence of stars,
nontrivial chemistry, and any type of observer.

In fact it is believed that there are combinatorially many possibilities,
with estimates of the number such
as 10^500 or even 10^100000.  This leads to a problem of understanding how
the choice realized in
our universe was found in early cosmology.  A decade ago, in work
of Frederik Denef and myself,
the computational complexity of this problem was studied for the first
time.  It was argued that (in a sense)
the problem of finding a ``viable'' choice -- one which is compatible
with stars, nontrivial chemistry, and any type of observer --
is NP hard.  Recently we were joined by Brian Greene in a renewed attack on
this
problem, in which we develop a new picture of quantum cosmology as
computationally limited.  We postulate that the
structure of the extra dimensions is one that could be easily found by a
computer programmed to search
for viable cases.  I will explain our progress towards making this idea
precise, describe the problems which arise in
analyzing it, and discuss the prospects for making any testable predictions
from it.



Host: David McAllester, *mcallester at ttic.edu* <mcallester at ttic.edu>


For more information on the colloquium series or to subscribe to the
mailing list, please see http://www.ttic.edu/colloquium.php




Mary C. Marre
Administrative Assistant
*Toyota Technological Institute*
*6045 S. Kenwood Avenue*
*Room 504*
*Chicago, IL  60637*
*p:(773) 834-1757*
*f: (773) 357-6970*
*mmarre at ttic.edu <mmarre at ttic.edu>*
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