At 9 a.m. Switzerland time on Sept. 10, scientists in Geneva will flip a switch (or possibly type a command) -- and if all goes as planned, the first beam will circulate through the giant new particle accelerator known as the Large Hadron Collider (LHC).

To mark the occasion -- and to explain what it all means -- the physics department will hold a public forum at 6:30 p.m. Sept. 9 in Rockefeller Hall's Schwartz Auditorium.

For thousands of particle physicists around the world, including many at Cornell, the first data from the LHC will be a landmark event. The massive machine, built by the European Organization for Nuclear Research (CERN) after decades of planning, millions of hours of research and centuries of accumulated knowledge, could help answer some of science's most fundamental questions about the nature of the universe.

So as Cornell theoretical physicist Yuval Grossman and colleagues gear up for the event, they're looking forward to sharing more information, and their enthusiasm, with the public. Not to mention dispelling concerns about the accelerator's potential for creating Earth-gobbling black holes -- a possibility that is so infinitesimally small, physicists say, that it practically doesn't exist.

"We know in quantum mechanics it's all about probability, and in principle when I turn on my cell phone there's a probability that I will destroy the Earth," said Grossman, who with assistant professor of physics Peter Wittich will be speaking at the Sept. 9 forum. "But as we are all sure cellphones will not destroy the Earth, the same is true for the LHC."

Still, Grossman understands that people have questions. "The worry is legitimate, and the questions are very well posed," he said. "But we do have a good answer."

Particle collisions like those that will happen in the LHC are happening all around us, all the time, he said. So while the potential for harm is essentially nonexistent, the potential benefit is huge -- from the possibility of answering questions about mass, dark matter and the origins of the universe, to spinoffs including lifesaving medical applications and advances in computer science.

"I would really like to have people know what's going on here at Cornell, and what is going on in general in the world in terms of physics -- why we are doing it, and why it is good for society," Grossman said. "It is worth getting very excited about."