Falling into a black hole could wipe out your past and give you an unlimited number of futures

If you ever fell into a black hole, your body would most likely be ripped into shreds and become 'spaghettified'. At least that's the theory put forward by most physicists today. But a new study is challenging that claim by suggesting there may be some black holes that you could survive - although doing so may put you into a strange reality.

These black holes would destroy your past life and trap you in a parallel universe with an infinite number of possible futures. This is because the universe on the other side would not be governed by the rules of cause and effect that apply in ours.

As a result you could 'live forever', researchers claim. A mathematician from the University of California, Berkeley, made the discovery after crunching the numbers on a particular type of black hole with an electrical charge.

In the real world, your past determines your future and this determinism rules the laws of physics. This means that the physical laws of the universe do not allow for more than one possible future. If a scientist knew exactly how the universe began, they could theoretically calculate what will happen for the rest of time and all of space.

UC Berkeley postdoctoral fellow Peter Hintz found that, for something known as 'Reissner-Nordström-de Sitter' black holes, this determinism does not apply. If a space traveller were somehow able to venture into one of these relatively benign black holes, they may be able to survive the experience.

This would eventually give them passage from our deterministic world into a non-deterministic black hole and, in theory, out the other side. If they were able to avoid the black hole's infinitely dense singularity, they could emerge into another universe on the other side.

What would happen next is unknown, as in a non-deterministic universe the relationship between cause and effect would no longer exist.  Any and every outcome of everything that is, was and will be possible could exist at the same time.

This strange phenomenon is a quirk of Albert Einstein's general theory of relativity which, for the past century, has been the standard model used to explain the way gravity works.

'Normally in physics, initial conditions and the laws of physics are supposed to fully determine what happens to any physical system,' said Robert Mann, Professor of physics and applied mathematics at the University of Waterloo, Canada, who was not involved with the study.  'However general relativity doesn't have this feature, curiously enough.  If I give you an initial distribution of matter and energy over the entire universe, the equations of general relativity in general will not predict the entire future of the space-time.'

Professor Hintz studied a specific type of non-rotating black hole, which have a so-called Cauchy horizon within their event horizon.

The Cauchy horizon is the spot where determinism technically breaks down, where the past no longer determines the future. Physicists have argued that no observer could ever pass through the Cauchy horizon point because they would be annihilated.

As an observer approaches the Cauchy horizon time slows down, since clocks tick slower in a strong gravitational field, they argue. As light, gravitational waves and anything else encountering the black hole fall inevitably toward the Cauchy horizon, an observer also actually falling inward would eventually see all this energy barrelling in on them at the same time. 

In effect, all the energy the black hole sees over the lifetime of the universe would hit the Cauchy horizon at the same time, blasting into oblivion any observer who made it that far.

Dr Hintz's curious calculations uncovered an exception to this rule with Reissner-Nordström-de Sitter black holes. In a written statement, he said: 'No physicist is going to travel into a black hole and measure it. This is a math question.

'But from that point of view, this makes Einstein's equations mathematically more interesting. This is a question one can really only study mathematically, but it has physical, almost philosophical implications, which makes it very cool. There are some exact solutions of Einstein's equations that are perfectly smooth, with no kinks, no tidal forces going to infinity, where everything is perfectly well behaved up to this Cauchy horizon and beyond. After that, all bets are off.'

Dr Hintz's equations only work because the our universe is really expanding at an increasing rate.

Because space-time is being increasingly pulled apart, much of the universe on the other side of the black hole will not affect it at all. As energy can't travel faster than the speed of light, only matter and energy which is within the black hole's observable horizon will be pulled in over its lifetime.

In this scenario, the expansion of the universe would counteract the amplification caused by time dilation inside the black hole that would appear to cause all matter to hit the observer in one go. For certain situations, such as in Reissner-Nordström-de Sitter black holes, this stretching of space-time would eventually cancel the time dilation entirely, allowing a traveller to pass through unharmed.

The full findings of the study were published in the journal Physical Review Letters.