Gravitational Effects of a Small Primordial Black Hole Passing Through the Human Body

TL;DR

This paper analyzes the potential harm caused by primordial black holes passing through the human body, finding that only black holes above a certain mass could cause serious injury, but such events are extremely rare.

Contribution

It provides a quantitative assessment of the minimum black hole mass needed to cause harm and concludes such events are negligible due to their rarity.

Findings

Shock wave damage is the dominant injury mechanism.

Minimum mass for serious injury is approximately 1.4 x 10^17 grams.

Primordial black holes above this mass are too rare to impact humans.

Abstract

The gravitational effects of a primordial black hole (PBH) passing through the human body are examined, with the goal of determining the minimum mass necessary to produce significant injury or death. Two effects are examined: the damage caused by a shock wave propagating outward from the black hole trajectory, and the dissociation of brain cells from tidal forces produced by the black hole on its passage through the human body. It is found that the former is the dominant effect, with a cutoff mass for serious injury or death of approximately $M_{PBH} > 1.4 \times 10^{17} {\rm g}$. The number density of primordial black holes with a mass above this cutoff is far too small to produce any observable effects on the human population.