|
Towards
a new test of general relativity?
23 March 2006
Overall picture
of the experimental apparatus where the Gravitomagnetic
London Moment in rotating superconductors has been detected.
Credits: ESA
|
|
Two papers
detailing the work are now being considered for publication.
|
Local Photon and
Graviton
Mass
and its
Consequences
|
Experimental
Detection of the Gravitomagnetic London Moment
|
Scientists funded by the
European Space Agency have measured the gravitational equivalent
of a magnetic field for the first time in a laboratory. Under
certain special conditions the effect is much larger than
expected from general relativity and could help physicists to
make a significant step towards the long-sought-after quantum
theory of gravity.
Just as a moving electrical
charge creates a magnetic field, so a moving mass generates a
gravitomagnetic field. According to Einstein's Theory of General
Relativity, the effect is virtually negligible. However, Martin
Tajmar, ARC Seibersdorf Research GmbH, Austria; Clovis de Matos,
ESA-HQ, Paris; and colleagues have measured the effect in a
laboratory.
Their experiment involves a
ring of superconducting material rotating up to 6 500 times a
minute. Superconductors are special materials that lose all
electrical resistance at a certain temperature. Spinning
superconductors produce a weak magnetic field, the so-called
London moment. The new experiment tests a conjecture by Tajmar
and de Matos that explains the difference between high-precision
mass measurements of Cooper-pairs (the current carriers in
superconductors) and their prediction via quantum theory. They
have discovered that this anomaly could be explained by the
appearance of a gravitomagnetic field in the spinning
superconductor (This effect has been named the Gravitomagnetic
London Moment by analogy with its magnetic counterpart).
Small
acceleration sensors placed at different locations close to the
spinning superconductor, which has to be accelerated for the
effect to be noticeable, recorded an acceleration field outside
the superconductor that appears to be produced by
gravitomagnetism. "This experiment is the gravitational
analogue of Faraday's electromagnetic induction experiment in
1831.
It demonstrates that a
superconductive gyroscope is capable of generating a powerful
gravitomagnetic field, and is therefore the gravitational
counterpart of the magnetic coil. Depending on further
confirmation, this effect could form the basis for a new
technological domain, which would have numerous applications in
space and other high-tech sectors" says de Matos. Although
just 100 millionths of the acceleration due to the Earth’s
gravitational field, the measured field is a surprising one
hundred million trillion times larger than Einstein’s
General Relativity predicts. Initially, the researchers were
reluctant to believe their own results.
|
An angularly
accelerated superconductive ring induces non-Newtonian
gravitational fields in its neibourghood.
Credits: ESA
|
"We ran more than 250
experiments, improved the facility over 3 years and discussed the
validity of the results for 8 months before making this
announcement. Now we are confident about the measurement,"
says Tajmar, who performed the experiments and hopes that other
physicists will conduct their own versions of the experiment in
order to verify the findings and rule out a facility induced
effect.
In parallel to the experimental
evaluation of their conjecture, Tajmar and de Matos also looked
for a more refined theoretical model of the Gravitomagnetic
London Moment. They took their inspiration from
superconductivity. The electromagnetic properties of
superconductors are explained in quantum theory by assuming that
force-carrying particles, known as photons, gain mass. By
allowing force-carrying gravitational particles, known as the
gravitons, to become heavier, they found that the unexpectedly
large gravitomagnetic force could be modelled.
"If
confirmed, this would be a major breakthrough," says Tajmar,
"it opens up a new means of investigating general relativity
and it consequences in the quantum world."
Source
/ Credit: ESA
|
