Let’s talk cosmology

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It didn’t take long for moderator Ira Flatow, host of National Public Radio’s Talk of the Nation: Science Friday program, to set aside his prepared questions for the four renowned scientists seated on the Millennium Park Harris Theater stage. Audience members—who almost filled the 1,525 seats at the free public panel sponsored by the University’s Department of Astronomy and Astrophysics, the Kavli Institute for Cosmological Physics, the Adler Planetarium and Astronomy Museum, and the Illinois Humanities Council—had lined up six and seven deep at two microphones with their own queries.

These folks had done their reading. “Are dark matter and antimatter the same thing?” one questioner began. “And does the existence of dark matter put in question the big bang theory?” In fact, answered Harvard physicist Lisa Randall, the two are different concepts. While antimatter can “annihilate matter,” dark matter is “dark” because it doesn’t interact electromagnetically, or with photons. It does, however, interact with gravity. As for the big bang, dark matter is actually consistent with the theory.

When Flatow said he’d like to move on to extra dimensions, a corner of the crowd shouted that there was another audience question. The moderator could be forgiven for overlooking the asker, an elementary schooler who couldn’t reach the microphone without his father releasing it from its stand. “Is matter energy?” the boy asked. “And that tiny spark that started the big bang—how were matter and energy formed?” Chicago cosmologist Rocky Kolb joked to the child: “We’re hiring graduate students.” To answer his first question, Randall offered, “Matter is a form of energy in a sense.” Responding to his other query, she said, “We wish we knew that, but we don’t.” Flatow followed up with, “And what came before the big bang?” Case Western physicist Lawrence Krauss noted that Stephen Hawking would argue that “isn’t a good question.” If time arose only after the big bang, then what came before it doesn’t matter. Randall added, “It’s somewhat analogous to asking, What’s north of the north pole?”

A.M.B.

Photo: The discussion over, Flatow thanks the panelists: Wendy Freedman, Lawrence Krauss, Rocky Kolb, and Lisa Randall.

December 14, 2005