Hawking floats on a zero-gravity jet. The 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 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., the company that owns the jet. Zero Gravity Corp.