ethan@utastro.UUCP (Ethan Vishniac) (12/19/84)
[] >I once read a SF story about some astronauts that found an alien >transmitter on Mars. It had a "microscopically small black hole" >that was induced to vibrate by magnetic waves. According to the >story, the gravitic disturbance created affected the entire space >fabric of the universe simultaneously. As long as we're citing science fiction stories in discussing physics we should have the correct reference. The story in question is "The Hole Man" by Larry Niven. The gravity waves generated did not affect "the entire space fabric of the universe simultaneously". They simply spread out at the speed of light in accordance with the kind of pedestrian physics we all know and love. >Does anyone know of any experiments, domestic or cosmic, that >have in some way determined "the speed of gravity"? Since gravity waves have never been directly detected the answer is clearly no. However, the theories of special and general relativity are in good health, and the effects of the generation of gravity waves have been observed to be in accordance with GR. (i.e. the energy loss from a tightly bound binary pair is in accordance with GR). This does tend to reinforce the idea that Einstein got it right the first time. The above will not be the official opinion of the University of Texas until such time as it can be reliably ascertained that hell has frozen over to a depth of at least 10 meters. "I can't help it if my Ethan Vishniac knee jerks" {charm,ut-sally,ut-ngp,noao}!utastro!ethan Department of Astronomy University of Texas Austin, Texas 78712