14 DAY TRIAL // A gravitomagnetic field is an approximation to the Einstein field equations for general relativity, valid under certain conditions, a reformulation of gravity described as a so far fictitious force around a moving, gravitating body.
Much like a moving electric charge that creates a magnetic field, a gravitomagnetic force makes a free-falling object near a massive rotating object rotate itself. This prediction, often loosely referred to as a gravitomagnetic effect, is among the last basic predictions of general relativity yet to be directly tested.
Now, a scientist at the University of Missouri-Columbia claims that we'll never find evidence of this effect because we don't look for it with the right tools. He said that the Lunar Laser Ranging (LLR), which is being used to detect the gravitomagnetic field, is inefficient because LLR is not currently sensitive to gravitomagnetism and not effective in measuring it.
The LLR uses a gyroscope in orbit around the earth to measure for the field, called Gravity Probe B, that shoots a laser beam at mirrors called retroflectors, which are located on the moon and then measures the roundtrip light travel time of the beam. Then, it processes data from two sets of mathematical equations, one related to the motion of the moon around the earth and the other related to the propagation of the beam from earth to the moon.
"According to Einstein's theory, only coordinate-independent quantities are measurable," said Sergei Kopeikin, associate professor of physics in MU's College of Arts and Science.
"The effect the LLR scientists claimed as detectable doesn't exist, as it vanishes in the observer's frame. The equations add up to zero, having nothing to do with the real data. The results appear this way because of insufficient analytic control of the coordinate effects in the sophisticated computer code used for numerical LLR data processing. We need to focus on the real physical effects of gravity, not the mathematical effects depending exclusively on the choice of coordinates."
Recently, physicists from the European Space Agency released a paper detailing their mechanisms for creating artificial gravity, claiming that they recorded such a gravitometric field. If confirmed, a gravitomagnetic field of measurable magnitude was produced for the first time in a laboratory environment. These results may open up a new experimental window on testing general relativity and its consequences using coherent matter.
"If the existence of the gravitomagnetic field is confirmed, then our understanding of general relativity is correct and can be used to explain things such as quasar jets and accretion disks in black holes," said Kopeikin. "General relativity explains the origin of the universe, and that's important for all humankind, irrespective of religion or creed. We all live in the same world, and we must understand this place in which we live."