# Charged Black Holes Can Erase Your Past And Give You Infinite Number Of Possible Futures

In our world, the past determines the future. If physicists know the beginning of the universe, it is possible for them to calculate its future for all time and space.

### Black Holes With A Reset Button That Can Erase The Past

A mathematician from the University of California at Berkeley, however, claims that there are black holes in the universe that can press the reset button of history. He said that in an ever-expanding universe, these black holes can completely reset the past and the future.

Peter Hintz said mathematical calculations revealed that for some types of black holes in a universe, which expands at an accelerating rate like ours, there is a possibility to survive passage from a deterministic world into a non-deterministic black hole.

### Cauchy Horizon

This particular black hole is a standard non-rotating black hole with an electrical charge and the so-called Cauchy horizon within the event horizon, the boundary around a black hole beyond which nothing, not even light nor radiation, can escape.

The Cauchy horizon is where determinism break down, which means that here, the past no longer determines the future. If someone sets to venture into one of these black holes with a Cauchy horizon, he could survive but his past would be erased and he faces an infinite number of possible futures.

"It is no longer uniquely determined by full knowledge of the initial conditions," Hintz said. "That is why it's very troublesome."

### Charged Black Holes

Hintz discovered this type of black hole after working with colleagues who calculated how a black hole rings once struck by gravitational waves and which of its tones and overtones would last longest. They studied hypothetical charged, non-rotating objects called Reissner-Nordström-de Sitter black holes, which, in theory, would have a Cauchy horizon barrier.

Charged black holes are not likely to exist because they would attract oppositely charged matter until they become neutral. Nonetheless, the mathematical solution for charged black holes serves as proxies for what could happen inside rotating black holes.

"Charged black holes are not relevant in astrophysics because large imbalances of charge do not occur in nature. However, uncharged rotating black holes also exhibit an unstable Cauchy horizon," wrote Harvey Reall, from the University of Cambridge.

"Studying such black holes is harder than studying Reissner-Nordström black holes because rotating black holes possess fewer rotational symmetries than Reissner-Nordström black holes."

Hintz and colleagues reported their findings of Cauchy horizons inside charged black holes in *Physical Review Letters.*