Summer 2000 -- Vol. 17, No. 1

FACES OF PENN STATE

Abhay Ashtekar
Holder of Eberly Family Chair in Physics and
Director of Center for Gravitational Physics and Geometry

One small book has led to many big things for Abhay Ashtekar.  After reading "One, Two, Three  . . .  Infinity," written by physicist George Gamow, then-teenager Ashtekar discovered his love for cosmology and mathematics.  Since then, he has become a world-renowned physicist whose work has helped build a better understanding of the differing theories of general relativity and quantum mechanics.  He introduced a ground-breaking mathematical approach that helped redefine Albert Einstein's theory of relativity and make it more compatible with quantum theory.

His collaborative work with Lee Smolin, professor of physics at Penn State, and Carlo Rovelli, professor of physics at the University of Pittsburgh, which built on some of the earlier efforts of Roger Penrose, the Francis R. and Helen M. Pentz Distinguished Professor of Physics and Mathematics at Penn State, has helped scientists move toward a unification of the two theories, generally called "quantum gravity."  As Director of the Center for Gravitational Physics and Geometry at Penn State, a center that includes 36 scientists from the fields of astrophysics, math, and physics and ranks as the second-largest gravity think tank in the world, Ashtekar addresses the mysteries of the two divergent theories every day.

Although his theory cannot be directly tested using current technology, it is already accepted by many.  In a sense, the theory provides a means for examining how gravity might react as you examine smaller and smaller slices of space.

In addition to quantum gravity, Ashtekar works problems related to very strong gravitational fields such as those encountered near the Big Bang.

At the Center for Gravitational Physics and Geometry, other Penn State faculty members chase answers to related topics.  These include work on black holes and the Laser Inferferometer Gravitational-Wave Observatory (LIGO). With detectors located in Livingston, Louisiana, and Hanford, Washington, LIGO is designed to detect gravitational waves emitted by some of the cataclysmic and energetic events in the universe that cannot be observed in any other way.  Experimental research by Gabriela Gonzalez, assistant professor of physics, aims to improve the detection system used by LIGO, while theoretical work by Sam Finn, associate professor of physics, investigates the issue of physical intepretation of the data that LIGO will provide. Douglas Arnold, distinguished professor of mathematics, Pablo Laguna, associate professor of astronomy and astrophysics, and Jorge Pullin, associate professor of physics, lead a program to study collisions of black holes.  In addition, Pullin works on the relation between quantum gravity and a branch of mathematics known as knot theory.  Black holes are also among Smolin's interests.  His theory of "cosmological natural selection" proposes how our universe emerged from the black hole of another galaxy.

--By Steve Sampsell

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