Gravity waves, as yet undetected but predicted by Albert Einstein, may contain the answers to many questions about the universe. Soviet scientist Leonid Grishchuk and American scientist Kip Thorne describe their attempts to prove the existence of the waves. The episode also visits a gravity-wave detector prototype and describes the three-mile-long full-scale version, planned for construction in the late 1990's. Grishchuk and scientist Stephen Hawking meet.

• James F. Golway

• Hans Bethe
• Richard Chamberlain