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How Can Black Holes Change the Future?

VO: Ashley Bowman WRITTEN BY: Caitlin Johnson
Black holes. Wormholes. Space time. Scientists are still trying to understand it all, but they could hold the key to life, the universe and everything. In this video, we explore how black holes could confirm time travel theories, and how travelling through one really could change your future.
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How Can Black Holes Change the Future?


We’re told that the future is our own to forge and do with as we will; that we can make our own destiny and be whoever we want to be. But despite the apparent palpability of our fates, the human race has been infatuated with the idea of time travel for decades. The more knowledge we gain about outer space and our reality, the more we crave to entertain outlandish fantasies, and dream up impossible ideas.

But might even our most farfetched thoughts be actually possible? Potentially, and the solution may lie with one of the universe’s most intriguing phenomena: black holes. These deadly, greedy monsters don’t just entrap matter, light and sound, but they destabilize reality and space-time, too. Black holes are frightening and extraordinary, with their unique composition meaning that when the universe inevitably ends they will be the last things to die, collapsing in on themselves with nothing left to consume. Though, all of that is still trillions of years away.

Before breaching how they can specifically alter the future, it’s important to understand the effect that black holes have on time itself. While ‘time’ and its incremental units of measurement were made up by people, its progression is an undeniable truth – except within a black hole. Changing time is something that comes naturally to black holes, as the space-time continuum collapses the further into them it gets.

If you were to hypothetically travel into a black hole, from the outside an onlooker would see you travel into the ‘black’ event horizon, slow down, freeze completely, and then disappear. Meanwhile, deep within the hole itself, you are briefly free to look out at the world you’re leaving behind and – providing you happen to have a powerful enough telescope – watch the galaxy go by in fast-forward. This would give you an insight of sorts into the future – if very rapidly. However, the quite impractical issue is that once you reach this point at the event horizon it’d be impossible for you to escape. Unless you could travel faster than light – which nothing can.

You may have seen all of human history flash before your eyes, but as you’d be unable to leave, this incredible knowledge would be utterly useless. You’d be watching Earth and everyone you’ve ever known slowly march towards death, knowing that soon you yourself are going to have your atoms spaghettified into one long string before being devoured by the singularity. It doesn’t sound like a very fun way to divine the future, and even if you did see something good it’d be painfully bittersweet. Even were we able enter and leave the event horizon at will, time as experienced on the outside would have caught up to us, meaning we still would’ve left everything behind. Perhaps this could be considered a rudimentary form of time travel, but it’s still next to impossible to achieve.

Changing (or viewing) the future of mankind as a whole is one thing but changing the future for ourselves is something else entirely. In a very basic way you might argue that simply plunging into a black hole is a very hands-on method of changing your own future, even if the move did equate to suicide. But what if death isn’t what lies within the singularity?

Physicist Roger Penrose – and more recently a team led by Peter Hintz – have speculated that entering a black hole may, in fact, be a way to escape the deterministic features of our own universe. “Determinism” roughly means that everything that has ever happened and will ever happen has already been “determined” beforehand by mathematics and physics. This is how physics is used to predict the way events will unfold, and why if something happened to change our understanding of physics it would unravel everything we know about the universe. This means that freewill is, in a way, an illusion; you may have a choice between multiple outcomes, but according to the universe’s deterministic nature, you will always make one pre-determined choice, unable to travel back in time or to a parallel universe and see what an alternate outcome would be.

As a different option, Penrose proposes the theory of “cosmic censorship”. This rests on something called the “Cauchy horizon”, which is further beyond the point-of-no-return “event horizon”. It’s a place where all the existing rules of time and the universe are thrown out of the window. In order for a singularity to exist, it’s generally thought that a Cauchy horizon must also exist… And, once a hypothetical astronaut-slash-time traveller enters the black hole, avoids the other perils, and goes past the Cauchy horizon, time will cease to exist as we know it.

But, in this version of events it doesn’t just lead to watching things go by in super-speed. Instead, it would erase the determinism of everything we know right now, meaning that there are no rules forcing you to stick to your pre-destined future. You’d suddenly be able to live out an infinite number of futures but would also have your entire past (and all memories of it) completely erased. Hypothetically speaking, the passing of this barrier means that you – the you that people know and love – wouldn’t exist anymore either. You wouldn’t know what kind of world you had left behind, but equally you’d never be able to return and tell us what you’d discovered. In theory, the process could’ve already happened to all of us.

Another scientist, Richard Bower, has different ideas about the time travel potential of black holes - ones where the lucky participant may actually live – as their own selves – to tell the tale. Bower suggests that black holes surely do hold the secret to this most unattainable sci-fi dream, pointing out that while current scientific theory says that time travel is impossible, there was once an era when it was also thought that flying could never be achieved.

Again focusing on what lies within the event horizon, Bower argues that backward time travel could even be doable – but only in parallel worlds that are somehow created within the space and time mish-mash of the black hole itself. This would obviously explain why, if time travel does someday become a reality, we’ve never been awash with people trying to stop the Titanic from sinking or attempting to assassinate a young Adolf Hitler; they’re all in parallel universes.

Black holes as a method of transportation, be that as portals from one universe to another or simply between points in our own universe, is an idea often entertained in science-fiction. Since we can’t actually see the inside of a black hole, just the void of the event horizon, there’s long been speculation that perhaps they aren’t the all-consuming entities we think they are: maybe they’re wormholes, either through time, space, or both. The issue with wormholes, however, is very similar to the issue with black holes; we just don’t know what would happen if we ever went through one. And, if wormholes do exist we don’t yet have the tech to determine which black holes will painfully kill you and which will spit you out into a brand-new galaxy. And even if you did survive and end up in a new part of the universe, starting a life there with no feasible way to return to Earth might not be something many people are willing to try out.

Ultimately, using black holes as a scientific method of time travel may never be achieved by humanity. Aside from sending out a few lonely pioneers, it would be tremendously difficult to pinpoint an exact time and place to re-appear in. We’d be going in blind, and coming out who knows where, probably long dead.

But that’s not to say that black holes don’t hold the secret of how we could achieve time travel with our own science and technology. In fact, they very well might because of the proven ways they distort time as it gets dragged towards the singularity. However, unless we manage to prove the laws of physics wrong and learn to travel faster than light so that we could enter and leave a black hole at will, we’re never likely to find out what that ‘secret’ is.
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