Nethotrons: exploring the possibility of measuring relativistic spin precessions, from Earth's satellites to the Galactic Centre

TL;DR

This paper explores the potential of using natural and artificial rotating objects, such as satellites and pulsars, to measure relativistic spin precessions caused by Earth's and the Galactic Centre's gravitational fields, expanding current measurement methods.

Contribution

It investigates the feasibility of detecting relativistic spin precessions using satellites and pulsars, proposing new observational avenues beyond the existing Gravity Probe B experiment.

Findings

Gravity Probe B achieved 0.3% and 19% accuracy in measuring relativistic effects.

Potential to use Earth's laser-ranged satellites for future measurements.

Pulsars near the Galactic Centre could provide new tests of relativistic spin precessions.

Abstract

By ``nethotrons'', from the ancient Greek verb for to ``spin'', it is meant here a natural or artificial rotating object, like a pulsar or an artificial satellite, whose rotational axis is cumulatively displaced by the post-Newtonian static (gravitoelectric) and stationary (gravitomagnetic) components of the gravitational field of some massive body around which it freely moves. Until now, both relativistic effects have been measured only by the dedicated space-based mission Gravity Probe B in the terrestrial environment. It detected the gravitoelectric de Sitter and gravitomagnetic Pugh-Schiff spin precessions of four superconducting gyroscopes accumulated in a year after about 50 years from conception to completion of data analysis at a cost of 750 million dollars to $0.3$ and $19$ per cent accuracy, respectively. The perspectives to measure them also with long-lived Earth's laser-ranged geodetic satellites, like those of the LAGEOS family or possibly one or more of them to be built specifically from scratch, and pulsars orbiting the supermassive black hole in the Galactic Centre, yet to be discovered, are preliminarily investigated. The double pulsar PSR J0737-3039A/B is examined as well.