Velocity Measurements in Some Classes of Alternative Gravity Theories

TL;DR

This paper investigates how test particle velocities near black holes differ in alternative gravity theories, showing they do not reach light speed at the horizon when considering generalized observers.

Contribution

It introduces a generalized observer framework to accurately measure velocities in static spherically symmetric metrics across Einstein and alternative gravity theories.

Findings

Test particle velocities do not approach light speed at the horizon.

Generalized observers provide consistent velocity measurements.

Results apply to well-known solutions in alternative gravity theories.

Abstract

The general misconception regarding velocity measurements of a test particle as it approaches black hole is addressed by introducing generalized observer set. For a general static spherically symmetric metric applicable to both Einstein and alternative gravities as well as for some well known solutions in alternative gravity theories, we find that velocity of the test particle do not approach that of light at event horizon by considering ingoing observers and test particles.