is a somwhat bizarre consequence of Einstein's
theory of relativity
. Also known as the Lense-Thirring effect
, named after the two Austrian physicists, Joseph Lense
and Hans Thirring
who predicted it in 1918.
In the same way that a spinning bowling ball
dropped into syrup
will drag the liquid around in a swirling vortex
, so a rotating
mass will drag spacetime
around into whirl.
This effect has been experimentally
confirmed by observing some of the most massive
objects in the universe
, black holes
and neutron stars
. In 1997 the NASA Rossi X-ray Timing Explore
r (RXTE) made detailed observations
of the spinning accretion disks
around two black holes, (GRS 1915+105 and GRO J1655-40), which showed the disks to be precessing
, much like a spinning top
as it slows down. In the case of GRO J1655-40, a seven solar mass
hole, the rate of the precession is 30 times a second, and the only explanation
that makes any sense, is frame dragging, caused by the huge space-time distortion of the spinning black hole.
Because these objects are so far away, and the black hole physics
book is still being written, a better test would be to measure the frame dragging caused by the Earth's
rotation. NASA's Gravity Probe B
, (still in development as of 4/2001) which when orbiting
the Earth, will contain 4 gyroscopes
spinning in bath of 400 gallons of superfluid helium
, will hopefully provide definitive evidence.
Frame dragging might lend weight to Mach's principle
, help explain the jets shooting from quasars
. In fact Einstein's theory is known to be incomplete, and precise measurements of frame dragging may highlight any discrepancies caused by the grand unification
theories that must succeed it..
For more, see the Gravity Probe B web site http://einstein.stanford.edu/