In the News
“ One tends to think of methamphetamine as being a drug of abuse largely for fairly advanced organisms.... It was quite nifty to try and
look at what’s happening in the humble fly. ” — DESMOND SMITH, PAGE 14
to test Einstein
finally pays off
Gravity Probe B measures
effect predicted by relativity
By Devin Powell
The longest-running project in NASA’s history has completed its mission. Gravity Probe B has finally confirmed that the Earth
drags spacetime around as it rotates, like
a spoon twisting in a jar of honey.
Other experiments had already confirmed this “frame-dragging” effect,
predicted by Einstein’s theory of general relativity. The new results, marred
by technical difficulties, won’t set any
records for precision.
But for those who have supported
the beleaguered project, which was
defunded by NASA three years ago, the
end of its saga is a triumph in itself.
“We’re proud that our dream wasn’t
completely lost,” says Stanford University physicist Francis Everitt, who has
worked on the project for 49 years. “The
science is complete.”
In 1959 and 1960, the era of Sputnik,
MIT physicist George Pugh and
Stanford physicist Leonard Schiff
independently proposed launching a
gyroscope into orbit to put Einstein to
the test. In Einstein’s universe, where
gravity distorts spacetime, the spinning Earth should deflect the tilt of an
orbiting gyroscope over time.
Everitt arrived at Stanford in 1962 to
Five decades after its conception and seven years since launch, Gravity Probe B has gauged the relativistic twisting of spacetime to a precision of 19 percent.
help build the world’s best gyroscope.
This effort, Gravity Probe B, would ultimately cost NASA at least $750 million.
By Everitt’s count, the project was nearly
canceled seven times.
But on April 20, 2004, a spacecraft
carried four quartz spheres into a polar
orbit. The size of Ping-Pong balls and
coated with the superconductor niobium, the spheres were the roundest
objects ever created by human beings. A
puff of gas started the gyros spinning, an
onboard telescope lined them up neatly
with the star IM Pegasi and the probe
collected data until August of 2005.
The first analysis of this data revealed
unexpected anomalies. The gyroscopes
had behaved badly — wandering around
and pointing in strange orientations.
Irregular patches on the surfaces of
the spheres were to blame. Everitt knew
about these patches and expected inter-
actions with the gyroscope housings that
would create small forces, or torques.
But unanticipated patches on the
housings themselves amplified these