What Happens If a Tiny Black Hole Passes Through Your Body?

A Vanderbilt University professor has explored the hypothetical effects of a primordial black hole passing through a human body. Robert Scherrer calculated how such an event might unfold, including the potential damage caused by tidal forces. The study also addresses the extremely low probability of this ever happening. Scherrer found that a black hole with a mass between 7 × 10⁷⁸ and 7 × 10⁷⁹ grams could tear brain cells apart. This happens because the black hole’s gravity pulls more strongly on one side of a cell than the other. A larger black hole, exceeding 1.4 × 10⁷⁹ grams, could release energy comparable to a .22-calibre bullet, making it lethal.

Below this mass threshold, a primordial black hole would pass through the body without any noticeable effect. The odds of such an encounter in a person’s lifetime are less than one in ten trillion. Physicists have long considered primordial black holes as possible candidates for dark matter, and Scherrer’s work now sets new limits on their potential abundance.

The idea of microscopic black holes as weapons is not new. In 1974, science fiction writer Larry Niven depicted a murder committed using one in a short story. The study highlights the extreme unlikelihood of a primordial black hole ever affecting a human. It also refines scientific understanding of these objects as possible components of dark matter. The findings provide clearer constraints on their existence and behaviour in the universe.