Behavior of a test gyroscope moving towards a rotating traversable wormhole (original) (raw)

Study of Geodesics and the Frame-dragging effect in a Rotating Traversable Wormhole

arXiv: General Relativity and Quantum Cosmology, 2016

The complete equatorial causal geodesic structure of a rotating traversable wormhole is analyzed and it has been shown that the ISCO (Innermost Stable Circular Orbit) coincides at the throat of the wormhole for the retrograde rotation. By studying the effective potential we also find the radius of the circular photon orbit. The Periastron precession frequency and the nodal precession frequency have been derived for both of the direct and retrograde rotation. Moreover, we derive the exact Lense-Thirring precession frequency of a test gyro for the said wormhole and we show that this frequency is inversely proportional to the angular momentum (a) of the wormhole along the pole in a certain range of r (r < 16a 2 ) whereas it is directly proportional to the angular momentum of the spacetime for the other compact objects like black holes and pulsars.

Gyroscope precession and general relativity

American Journal of Physics, 2001

Precession of a gyroscope in the presence of a gravitational field is of considerable interest, on account of the soon to be launched satellite test and because of its connection to Mach's principle. Nevertheless, this topic is not generally covered in the curriculum because of the mathematical sophistication required. We examine some of the simple physics involved and argue that by examining simple graviton-elementary particle couplings one can easily understand this phenomenon.

Gyroscope precession in cylindrically symmetric spacetimes

Classical and Quantum Gravity, 2000

We present calculations of gyroscope precession in spacetimes described by Levi-Civita and Lewis metrics, under different circumstances. By doing so we are able to establish a link between the parameters of the metrics and observable quantities, providing thereby a physical interpretation for those parameters, without specifying the source of the field.

Spinning test particle motion around a traversable wormhole

Physical Review D

The motion of spinning test particles around a traversable wormhole is investigated using the Mathisson-Papapetrous-Dixon equations, which couple the Riemann tensor with the antisymmetric tensor S αβ , related to the spin of the particle. Hence, we study the effective potential, circular orbits, and innermost stable circular orbit (ISCO) of spinning particles. We found that the spin affects significantly the location of the ISCO, in contrast with the motion of nonspinning particles, where the ISCO is the same in both the upper and lower universes. On the other hand, since the dynamical four-momentum and kinematical four-velocity of the spinning particle are not always parallel, we also consider a superluminal bound on the particles motion. In the case of circular orbits at the ISCO, we found that the motion of particles with an adimensional spin parameter lower (greater) than s ¼ −1.5 (1.5) is forbidden. The spin interaction becomes important for Kerr black hole orbiting super massive wormholes (SMWH). The motion of spinning test particles around a rotating wormhole is in process, and we will present it in a new manuscript soon.

Spinning gyroscope in an acoustic black hole: precession effects and observational aspects

The European Physical Journal C

The exact precession frequency of a freelyprecessing test gyroscope is derived for a 2 + 1 dimensional rotating acoustic black hole analogue spacetime, without making the somewhat unrealistic assumption that the gyroscope is static. We show that, as a consequence, the gyroscope crosses the acoustic ergosphere of the black hole with a finite precession frequency, provided its angular velocity lies within a particular range determined by the stipulation that the Killing vector is timelike over the ergoregion. Specializing to the 'Draining Sink' acoustic black hole, the precession frequency is shown to diverge near the acoustic horizon, instead of the vicinity of the ergosphere. In the limit of an infinitesimally small rotation of the acoustic black hole, the gyroscope still precesses with a finite frequency, thus confirming a behaviour analogous to geodetic precession in a physical non-rotating spacetime like a Schwarzschild black hole. Possible experimental approaches to detect acoustic spin precession and measure the consequent precession frequency, are discussed.

Gravity Probe-B, a Gyro Test of General Relativity in a Satellite

Automatic Control in Aerospace 1992, 1993

Gravity Probe-B is the relativity gyroscope experiment being developed by NASA and Stanford University to test two extraordinary, unverified predictions of Albert Einstein's general theory of relativity. The experiment will check very precisely, tiny changes in the directions of spin of fo~r gyroscopes contained in an Earth satellite orbiting at 400-mile altitude directly over the poles. So free are the gyroscopes from disturbance that they will pr?vide an almost perfect space-time reference system. They wlII measure how space and time are warped by the presence of the Earth, and, more profoundly, how the Earth's rotation drags space-time around with it. These effects, though small for the Earth, have far-reaching implications for the nature of matter and the structure of the Universe.

The three-fold theoretical basis of the Gravity Probe B gyro precession calculation

Eprint Arxiv 1405 5511, 2014

The Gravity Probe B (GP-B) experiment is complete and the results are in agreement with the predictions of general relativity (GR) for both the geodetic precession, 6.6 arcsec/yr to about 0.3%, and the Lense-Thirring precession, 39 marcsec to about 19%. This note is concerned with the theoretical basis for the predictions. The predictions depend on three elements of gravity theory, firstly that macroscopic gravity is described by a metric theory such as general relativity, secondly that the Lense-Thirring metric provides an approximate description of the gravitational field of the spinning earth, and thirdly that the spin axis of a gyroscope is parallel displaced in spacetime, which gives its equation of motion. We look at each of these three elements to show how each is solidly based on previous experiments and well-tested theory. The agreement of GP-B with theory strengthens our belief that all three elements are correct and increases our confidence in applying GR to astrophysical phenomena. Conversely, if GP-B had not verified the predictions a major theoretical quandary would have occurred.

Gyroscope precession along unbound equatorial plane orbits around a Kerr black hole

Physical Review D

The precession of a test gyroscope along unbound equatorial plane geodesic orbits around a Kerr black hole is analyzed with respect to a static reference frame whose axes point towards the "fixed stars." The accumulated precession angle after a complete scattering process is evaluated and compared with the corresponding change in the orbital angle. Limiting results for the non-rotating Schwarzschild black hole case are also discussed.