The gravitomagnetic effect
will it be detected?
August 15, 2005
Frédéric Henry-Couannier now has a website where he presents and explains his work:
http://toronto.dess-res.univ-mrs.fr/sitefred
Sources:
and
NASA's Gravity Probe B spacecraft completes its first year in space
Start by enjoying the spectacle of the launch. I swear, you'll feel like you're there:
http://www.gravityprobeb.com/movies/launch01.mov
General Relativity has a rather peculiar aspect, which can for example be observed in the "Kerr metric," used to describe rotating massive objects. When an object has a very large mass, a phenomenon known as "frame-dragging" appears—literally, "dragging of the coordinate system." What does this mean? Imagine a system composed of two masses connected by a spring. This spring can be stretched in two ways:
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By rotating the system. Centrifugal force will then manifest.
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By "rotating space itself."
It turns out that people have asked these questions even before the advent of General Relativity. Newton initially postulated the existence of an absolute space, independent of any content. This is his famous bucket experiment (described in my comic book Cosmic Story).
Later, the philosopher Mach (1883) suggested that space (the "inertial reference frame" relative to which the motion of water must be considered to observe the effects) is locally "determined by its material content" (the opposite of Newton's view). Mach claimed that if you enclosed a system of two masses connected by a spring inside a very massive shell and rotated that shell rapidly, a "centrifugal force" would appear—not because the masses were being rotated, but because the space in which they were immersed was being rotated. In 1896, he encouraged the Friedländer brothers to perform this experiment, which yielded no conclusive results.
Today, experimentalists are revisiting this question about the relationship between space and matter. Consider a sub-critical neutron star (i.e., one with a mass less than 2.5 solar masses), an object we observe (the "pulsars"). In its immediate vicinity, spacetime can be described by the "Kerr metric," just as the "Schwarzschild metric" describes spacetime around a non-rotating object. Analysis of this Kerr solution to Einstein's equation leads to rather unusual conclusions. For example: if you consider a circular orbit around the object, aligned with its axis of rotation, the speed of light will not be the same depending on whether you move in the same direction as the object's rotation or in the opposite direction! Once again, it appears as if the object "drags spacetime along with it." This phenomenon has been named "frame-dragging."
What holds true for a neutron star should, in General Relativity, apply to any rotating mass, including Earth itself—except that the effects are then extremely small. Until recently, measuring them would have been impossible. But now, thanks to a very recent breakthrough, it has become possible to detect these effects, which is precisely why the "Gravity Probe B" spacecraft was launched. These phenomena are called "gravitomagnetic," and this term corresponds to a simple analogy: a moving electric charge creates a magnetic effect (a magnetic field). In General Relativity, it was decided that a moving mass must create a gravitomagnetic effect (which would manifest as a distortion of the gravitational field).
NASA's experiment, carried out with the help of Stanford University, achieves the required precision to detect the effects predicted by General Relativity—namely, a tiny variation in the rotation axis of gyroscopes orbiting Earth at an altitude of 720 km in a polar orbit (passing over the poles). The experiment aims to demonstrate how Earth's presence and its rotation drag and twist spacetime. (In the article on the site: "drag" = to pull along, "warp" = to twist.)
Other predictions.
Frédéric Henry-Couannier is a lecturer at the University of the Mediterranean. For the past year, he has produced the following publications:
Publication in a peer-reviewed journal:
International Journal of Modern Physics A [Particles and Fields; Gravitation; Cosmology; Nuclear Physics], Vol. 20, No. 11 (2005) 2341–2345
Presentations at international conferences:
Sixth Alexander Friedmann International Seminar on Gravitation and Cosmology, June 28 – July 3, 2004, Cargèse
Henry-Couannier Frédéric
Negative energies in QFT and GR, the dark side of gravity
5th Rencontres du Vietnam Particle Physics and Astrophysics, Hanoi, August 5–11
Henry-Couannier Frédéric
Negative energies in QFT and GR, the dark side of gravity
GdR SUSY, July 2004, Clermont-Ferrand
Henry-Couannier Frédéric
Negative energies in QFT and GR, the dark side of gravity
Albert Einstein Century Conference, July 18–22, 2005, Paris
Discrete symmetries and GR, the dark side of gravity
XVIII Spanish Relativity Meeting "A Century of Relativity Physics," September 6–10, 2005, Oviedo, Spain
Discrete symmetries and GR, the dark side of gravity
Preprints posted on arXiv:
gr-qc/0410055: "Discrete symmetries and general relativity: the dark side of gravity"
gr-qc/0404110: "Negative energies and time-reversal in quantum field theory and general relativity: the dark side of gravity"
gr-qc/0507065: "Negative energies and a constantly accelerating flat universe"
The articles published by Frédéric Henry-Couannier open up many new perspectives. In the article highlighted in red, predictions related to measurements made by the Gravity Probe B spacecraft are presented—measurements whose analysis is currently underway (publication of results from one year of observations is expected imminently). These predictions differ significantly from those derived from General Relativity.
There is a fundamental principle of General Relativity, considered untouchable, known as the
equivalence principle.
This principle states that there is no privileged reference frame. In other words: the laws of physics take the same form in all reference frames. What is a "reference frame"? It is a system for measuring space and time associated with a given observer. The equivalence principle assumes that there is no privileged observer. Yet Frédéric Henry-Couannier challenges this cornerstone of physics, which amounts to claiming that an "absolute space" exists (formerly called the "ether"). This would mean... giving Newton right against Einstein, by predicting effects related to the motion of objects relative to this absolute space.
What could this absolute space be, then, if it were the "space of cosmology"? (The "cosmotope," the place where the universe is located, as Tirésias might say.) In the universe, absolute vacuum does not exist...