Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userGravitomagnetic Flux Quantization in superconductors and a Method for the Experimental Detection of Gravitomagnetism in the Terrestrial Laboratory
52
0
0.0
(
0
)
Added by
Clovis Jacinto de Matos
Publication date
1999
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
It is extraordinarely difficult to detect the extremely weak gravitomagnetic (GM) field of even as large a body as the earth. To detect the GM field, the gravitational analog of an ordinary magnetic field, in a modest terrestrial laboratory should be that much more difficult. Here we show, however, that for certain superconductor configuration and topologies, it should be possible to detect a measurable GM field in the terrestrial laboratory, by using the properties of superconductors imposed by quantum mechanical requirements. In particular, we show that the GM Flux should be quantized in a superconductor with non-vanishing genus, just like the ordinary magnetic flux. And this magnetically induced, quantized GM Flux, for sufficiently high quantum number and favorable geometries, should be distinguishable from the effects produced by an ordinary magnetic field.
rate research
Read More
The difference in the proper azimuthal periods of revolution of two standard clocks in direct and retrograde orbits about a central rotating mass is proportional to J/Mc^2, where J and M are, respectively, the proper angular momentum and mass of the source. In connection with this gravitomagnetic clock effect, we explore the possibility of using spaceborne standard clocks for detecting the gravitomagnetic field of the Earth. It is shown that this approach to the measurement of the gravitomagnetic field is, in a certain sense, theoretically equivalent to the Gravity Probe-B concept.
The main theoretical aspects of gravitomagnetism are reviewed. It is shown that the gravitomagnetic precession of a gyroscope is intimately connected with the special temporal structure around a rotating mass that is revealed by the gravitomagnetic clock effect. This remarkable effect, which involves the difference in the proper periods of a standard clock in prograde and retrograde circular geodesic orbits around a rotating mass, is discussed in detail. The implications of this effect for the notion of ``inertial dragging in the general theory of relativity are presented. The theory of the clock effect is developed within the PPN framework and the possibility of measuring it via spaceborne clocks is examined.
We study the gravitomagnetism in the Scalar-Vector-Tensor theory or Moffats Modified theory of Gravity(MOG). We compute the gravitomagnetic field that a slow-moving mass distribution produces in its Newtonian regime. We report that the consistency between the MOG gravitomagnetic field and that predicted by the Einsteins gravitional theory and measured by Gravity Probe B, LAGEOS and LAGEOS 2, and with a number of GRACE and Laser Lunar ranging measurements requires $|alpha| < 0.0013$. We provide a discussion.
A new experiment aimed to the detection of the gravito-magnetic Lense-Thirring effect at the surface of the Earth will be presented; the name of the experiment is GINGER. The proposed technique is based on the behavior of light beams in ring lasers, also known as gyrolasers. A three-dimensional array of ringlasers will be attached to a rigid monument; each ring will have a different orientation in space. Within the space-time of a rotating mass the propagation of light is indeed anisotropic; part of the anisotropy is purely kinematical (Sagnac effect), part is due to the interaction between the gravito-electric field of the source and the kinematical motion of the observer (de Sitter effect), finally there is a contribution from the gravito-magnetic component of the Earth (gravito-magnetic frame dragging or Lense-Thirring effect). In a ring laser a light beam traveling counterclockwise is superposed to another beam traveling in the opposite sense. The anisotropy in the propagation leads to standing waves with slightly different frequencies in the two directions; the final effect is a beat frequency proportional to the size of the instrument and its effective rotation rate in space, including the gravito-magnetic drag. Current laser techniques and the performances of the best existing ring lasers allow at the moment a sensitivity within one order of magnitude of the required accuracy for the detection of gravito-magnetic effects, so that the objective of GINGER is in the range of feasibility and aims to improve the sensitivity of a couple of orders of magnitude with respect to present. The experiment will be underground, probably in the Gran Sasso National Laboratories in Italy, and is based on an international collaboration among four Italian groups, the Technische Universitaet Muenchen and the University of Canterbury in Christchurch (NZ).
A self-consistent general relativistic configuration describing a finite cross-section magnetic flux tube is constructed. The cosmic solenoid is modeled by an elastic superconductive surface which separates the Melvin core from the surrounding flat conic structure. We show that a given amount $Phi$ of magnetic flux cannot be confined within a cosmic solenoid of circumferential radius smaller than $frac{sqrt{3G}}{2pi c^2}Phi$ without creating a conic singularity. Gauss-Codazzi matching conditions are derived by means of a self-consistent action. The source term, representing the surface currents, is sandwiched between internal and external gravitational surface terms. Surface superconductivity is realized by means of a Higgs scalar minimally coupled to projective electromagnetism. Trading the magnetic London phase for a dual electric surface vector potential, the generalized quantization condition reads: $e/{hc} Phi + 1/e Q=n$ with $Q$ denoting some dual electric charge, thereby allowing for a non-trivial Aharonov-Bohm effect. Our conclusions persist for dilaton gravity provided the dilaton coupling is sub-critical.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
