CAPE CANAVERAL, Fla. - Free of his wheelchair and tethered only to heart-rate and blood-pressure monitors, astrophysicist Stephen Hawking yesterday fulfilled a dream of floating weightless on a zero-gravity jet, a step he hopes leads to further space adventures.

"It was amazing," Hawking said after the flight.

The modified jet carrying Hawking, a handful of his physicians and nurses and dozens of others first flew up to 24,000 feet over the Atlantic Ocean off Florida. Nurses lifted Hawking and carried him to the front of the jet, where they placed him on his back atop a special foam pillow.

The jet then climbed to around 32,000 feet and made a parabolic dive back to 24,000 feet, allowing Hawking and the other passengers to experience weightlessness for about 25 seconds.

The plane made a total of eight parabolic dips, including two during which Hawking made two weightless flips like "a gold-medal gymnast," said Peter Diamandis, chairman of Zero Gravity Corp., which owns the jet.

Hawking, a mathematics professor at the University of Cambridge who has done groundbreaking work on the origins of the universe, has the paralyzing disease ALS, also known as Lou Gehrig's disease.

The 65-year-old was the first person with a disability to experience the flight by Zero Gravity, which has flown about 2,700 people out of Florida since late 2004 and began offering the flights in Las Vegas this week.

Unable to talk or move his hands and legs, Hawking can only make tiny facial expressions with the muscles around his eyes, eyebrows, cheek and mouth. He uses a computer attached to his wheelchair to talk for him in a synthesized voice. *