Physics Beyond Einstein: Contemplating Time's Beginning and End

Jessica Zachar, Research Unplugged intern
March 24, 2008
man holds his hands wide in front of poster

Abhay Ashtekar

"Gravity is everywhere—it is omnipresent!" announced Abhay Ashtekar last Wednesday to a packed house at the Penn State Downtown Theatre.

Ashtekar, holder of the Eberly family chair in Physics and Director of the Institute for Gravitation and the Cosmos at Penn State, kicked off the 10th semester of the Research Unplugged speaker series. Speaking to a diverse mix of students, faculty and community members, the distinguished physicist led a thought-provoking discussion on the historical evolution of concepts of space and time.

Opening the talk by taking us back to the 6th century B.C., Ashtekar explained that the two chief concerns of philosophers in that period were the nature of time and the question of whether the beginning and the end of the universe was unchanging and eternal.

Fast-forwarding to the 17th century, Ashtekar explained that Isaac Newton believed "space and time are like a stage-they are a given. And everything else-all of the stars, planets, you and me-are all actors in a drama and our stage is space and time." Added Ashtekar, " Newton argued that time will be there forever and we are the actors in this drama of evolution."

Of the 20th century's most renowned physicist, Albert Einstein, Ashtekar reminded the audience that it has been almost 100 years since Einstein developed the theory of general relativity, and that physics has evolved a considerable amount since then. "In physics, each new generation stands on the shoulders of giants," he commented.

In the last few moments of his talk, Ashtekar discussed loop quantum gravity, a theory that he helped pioneer and which seeks to unify Einstein's general relativity with quantum physics. Using loop quantum gravity, he noted, physicists can now posit the existence of another universe before the Big Bang, one with space-time geometry similar to our own, except that instead of expanding it is shrinking. "In place of a classical Big Bang," he suggested, "there is in fact a quantum Bounce."

Abhay Ashtekar, Ph.D., is holder of the Eberly family chair in physics and director of the Institute for Gravitation and the Cosmos in the Eberly College of Science. He can be reached at ava1@psu.edu.

Last Updated March 24, 2008