Sex on the gravity beach
One explanation of the
“action at a distance” phenomenon by which cosmic bodies are said to exert
a gravitational force on each other is that this force is a result of ripples
in the fabric of spacetime, called a gravitational wave. The waves, which
have not yet been directly detected (because of their incredibly long
wavelengths and low amplitude), were predicted by Einstein’s general theory
of relativity in 1916, but were widely disregarded until recently, because
of the apparent relationship between the idea of a spacetime fabric and the
discredited notion of an aether (which was an earlier and unverified
explanation of gravitational forces). The waves are thought to be produced
by the acceleration of large bodies of matter (such as binary star systems,
colliding black holes and supernovae), and are predicted to carry energy
and momentum. The measurement of such a wave would advance current theories
of gravity and gravitational behavior to a much more advanced level, and
would give physicists a solid foundation on which to build more plausible
theories on how to manipulate and interpret gravitational interaction. The
first full-scale experiment to attempt to measure gravitational waves is
the LIGO project, detailed on the next page.
predicted gravitational waves from black holes in different states
