Scientists funded by the European Space Agency have measured the
gravitational equivalent of a magnetic field for the first time in a
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.
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
"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.
For more detailed information, please contact:
Dipl-Ing Dr Martin Tajmar
Dr Clovis J. de Matos
* ESA's General Studies Programme
* Possible gravitational anomalies in quantum materials (pdf)