Hawking realized he could apply to black holes some theories he had developed to explain other puzzling states of matter and energy, particularly ones where the laws of physics seem to break down.
Of all the mysteries of the universe, however, Hawking said he would most like to understand how it is that we are here.
"The universe is so big, so smooth and yet just right enough for us to exist," Hawking said.
"I'm not religious in the normal sense," he added later. "I believe the universe is governed by the laws of science. The laws may have been decreed by God, but God does not intervene to break the laws," he said.
Hawking tested at least one of those laws on Thursday, defying gravity — for a moment anyway — by floating during one or more parabolic maneuvers aboard a specially modified Boeing 727. The ride is courtesy of Florida-based Zero Gravity Corp., which offers a commercial service similar to what NASA uses to train astronauts and test equipment prior to spaceflight.
Hawking hopes to reach the final frontier himself and has a reservation to fly aboard the commercial suborbital spaceship being developed by Virgin Atlantic Airways' offshoot, Virgin Galactic. Service is expected to begin in 2009.
