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.Paralyzed scientist Stephen Hawking, normally confined to a wheelchair, floats inside a zero-gravity jet on April 26. Hawking, who made two flips like 'a gold-medal gymnast,' called the experimence 'amazing.'