Symmetry and the arrow of time in theoretical black hole astrophysics

TL;DR

This paper explores the surprising presence of time-reversal symmetry in theoretical black hole astrophysics, challenging the conventional understanding of the arrow of time in large-scale cosmic structures.

Contribution

It identifies a time-symmetric harmonic behavior in black hole models, revealing a fundamental symmetry that parallels simple physical systems and suggests black holes have a more profound role in astrophysics.

Findings

Black hole models exhibit time-symmetric harmonic behavior.

A parallel is drawn between black hole dynamics and overdamped harmonic oscillators.

Black holes may influence astrophysical phenomena more fundamentally than previously thought.

Abstract

While the basic laws of physics seem time-reversal invariant, our understanding of the apparent irreversibility of the macroscopic world is well grounded in the notion of entropy. Because astrophysics deals with the largest structures in the Universe, one expects evidence there for the most pronounced entropic arrow of time. However, in recent theoretical astrophysics work it appears possible to identify constructs with time-reversal symmetry, which is puzzling in the large-scale realm especially because it involves the engines of powerful outflows in active galactic nuclei which deal with macroscopic constituents such as accretion disks, magnetic fields, and black holes. Nonetheless, the underlying theoretical structure from which this accreting black hole framework emerges displays a time-symmetric harmonic behavior, a feature reminiscent of basic and simple laws of physics. While we may expect such behavior for classical black holes due to their simplicity, manifestations of such symmetry on the scale of galaxies, instead, surprise. In fact, we identify a parallel between the astrophysical tug-of-war between accretion disks and jets in this model and the time symmetry-breaking of a simple overdamped harmonic oscillator. The validity of these theoretical ideas in combination with this unexpected parallel suggests that black holes are more influential in astrophysics than currently recognized and that black hole astrophysics is a more fundamental discipline.