Anyone can see that the past is different from the future. Anyone, that is, but theoretical physicists, whose equations do not seem to distinguish the past from the future. How, then, do physicists understand the "arrow of time" -- the fact that the past and future are so different?

The modern idea of eternal inflation -- the rapid expansion and decay of the universe -- has fundamentally changed cosmologists' views of the flow of time in ways that may allow us to understand why the future is different than the past, according to physicist Leonard Susskind.

In a June 26 SFI Community Lecture Wednesday in Santa Fe, Susskind asked how we know the past is different from the future and explores whether modern cosmology might revise our notions of time.

Watch the video of his presentation (74 minutes)

Susskind is the Felix Bloch Professor of Theoretical Physics at Stanford University and Director of the Stanford Institute for Theoretical Physics.

NEW: You can participate in SFI's 2013 Community Lecture live online. To watch a lecture as it happens, visit SFI's YouTube page. To participate in the live Twitter feed or ask questions of the speakers, @sfi_live or #sfi_live. For a complete listing of upcoming SFI community events, visit here.

The 2013 SFI Community Lecture Series is made possible through the generous support of Los Alamos National Bank.

Next lecture:

Wednesday, July 31, 7:30 p.m., New Problems, New Partnerships - What Tomorrow's University Must Be: Arizona State University President Michael Crow explains why conventional interdisciplinary approaches might not be sufficient to address tomorrow’s challenges. He then suggests a new kind of academic enterprise that adapts to emerging complexities and enhances our ability to manage tomorrow’s challenges.