Researchers create gravity in lab experiment
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 Earths gravitational
field, the measured field is a surprising one hundred million
trillion times larger than Einsteins General Relativity predicts.
Initially, the researchers were reluctant to believe their own
results.
"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."
The results were presented at a one-day conference at ESA's
European Space and Technology Research Centre (ESTEC), in the
Netherlands, 21 March 2006. Two papers detailing the work are now
being considered for publication. The papers can be accessed
on-line at the Los Alamos pre-print server using the references:
gr-qc/0603033 and gr-qc/0603032.
From European Space Agency
