Last year, Alan Alda, the actor, asked, "What is a flame?" and more than 800 people answered.
It was a challenge to scientists to explain a complex phenomenon in terms that an 11-year-old could understand.
Mr. Alda, who has long had a deep interest in science, played a key role in the founding of the Center for Communicating Science at Stony Brook University, and the center turned his question into a contest. An American physics graduate student at the University of Innsbruck in Austria won. His prize is a trip to the World Science Festival in New York in May. This year, the center has a new challenge: What is time?
The center had invited 11-year-olds to come up with questions. Among the 300 entries were "How does the brain store information?" and "Why are Shetland ponies so small?"
While flames are a well-understood, albeit difficult to explain, phenomenon, the nature of time is still a mystery.
"What it will help show is that science is not just a collection of facts, but a way of trying to understand the true nature of reality," Carl Safina, a chairman of the center's steering committee, said. "By that, I mean it isn't a settled question about what time really is, but there are scientific responses to the question."
The deadline for entries, at flamechallenge.org, is March 1. Again, 11-year-olds will decide the winner.
This article originally appeared in The New York Times.