Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

MU Physicist Says Testing Technique for Gravitomagnetic Field is Ineffective

04.06.2007
Existence of gravitomagnetic field related to Einstein's theory of general relativity, origin of universe

Albert Einstein's theory of general relativity has fascinated physicists and generated debate about the origin of the universe and the structure of objects like black holes and complex stars called quasars. A major focus has been on confirming the existence of the gravitomagnetic field, as well as gravitational waves. A physicist at the University of Missouri-Columbia recently argued in a paper that the interpretation of the results of Lunar Laser Ranging (LLR), which is being used to detect the gravitomagnetic field, is incorrect because LLR is not currently sensitive to gravitomagnetism and not effective in measuring it.

The theory of general relativity includes two different fields: static and non-static fields. The gravitomagnetic field is a non-static field that is important for the understanding of general relativity and the universe.

"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 Sergei Kopeikin, associate professor of physics in MU's College of Arts and Science. "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."

Kopeikin said there are four techniques used to test for the gravitomagnetic field. The first, called Gravity Probe B, used a gyroscope in orbit around the earth to measure for the field. It is supported by NASA and took nearly 40 years to develop; scientists recently conducted the experiment and are now analyzing the results. A second experiment involved satellites called Lageos and detected a gravitomagnetic field with a precision not exceeding 15 percent. A third experiment was developed by Kopeikin and other scientists in 2001 and used Very Long Baseline Interferometry (VLBI) to test for the gravitomagnetic field of Jupiter; this experiment detected the field with approximately 20 percent precision.

LLR is a recent testing technique. It involves shooting a laser beam at mirrors called retroflectors, which are located on the moon, and then measuring the roundtrip light travel time of the beam. In a response to a paper about LLR, Kopeikin argued in a letter published in Physical Review Letters that the interpretation of LLR results is flawed. He said analyses of his own and other scientists' research reveal that this approach to the LLR technique does not measure what it claims.

The LLR technique involves processing data with 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. These equations can be written in different ways based on "gauge freedom," the idea that arbitrary coordinates can be used to describe gravitational physics. Kopeikin analyzed the gauge freedom of the LLR technique and showed that the manipulation of the mathematical equations is causing scientists to derive results that are not apparent in the data itself.

"According to Einstein's theory, only coordinate-independent quantities are measurable," Kopeikin said. "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."

A reply from the scientists who support LLR also has published in Physical Review Letters and argues that there are aspects of the technique that cause them to believe it merits worth.

Katherine Kostiuk | EurekAlert!
Further information:
http://www.missouri.edu

More articles from Physics and Astronomy:

nachricht What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin

nachricht Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

NYSCF researchers develop novel bioengineering technique for personalized bone grafts

18.07.2018 | Life Sciences

Machine-learning predicted a superhard and high-energy-density tungsten nitride

18.07.2018 | Materials Sciences

Why might reading make myopic?

18.07.2018 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>