| Does gravity have a magnetic counterpart?
Spin any
electric charge and you get a
magnetic field.
Spin any mass and, according to
Einstein,
you should get a very slight effect that acts
something like magnetism.
This effect is expected to be so small that
it is beyond practical experience and ground laboratory measurement.
In a bold attempt to directly measure
gravitomagnetism, NASA
launched in 2004 the smoothest spheres ever manufactured into space to see
how they spin.
These four spheres, each roughly the size of a
ping-pong ball,
are the key to the ultra-precise
gyroscopes
at the core of
Gravity Probe B.
Last week, after accounting for persistent background signals,
the results were
announced --
the gyroscopes precessed at a rate consistent with the gravitational predictions of Einstein's
General
Theory of Relativity.
The results, which bolster existing findings, may have
untold long term benefits as well as shorter term benefits such as
better clocks and
global positioning trackers.
Credit:
Gravity Probe B Team,
Stanford,
NASA
|
