Stephen Hawking now thinks "there are no black holes"

The physicist, whose pioneering work on black holes in the 1970s made him a household name, has proposed a radical fudge to try and resolve a baffling paradox.

For a scientist whose career was made by his work on black holes, it might seem a little confusing to read that Stephen Hawking now thinks that they don’t exist. But that’s what “Information Preservation and Weather Forecasting for Black Holes”, the study Hawking published last week on arXiv, says: “there are no black holes”.

While this might seem surprising - after all, there’s a huge amount of (indirect) evidence that black holes exist, including a massive one several million times the mass of our Sun at the centre of the Milky Way - it’s really not. It’s Hawking’s latest attempt to solve a paradox that he, and other astrophysicists, have been grappling with for a couple of years.

So what’s he talking about? Here’s the background: black holes are objects which are so massive, with such strong gravity, that even light can’t escape. The distance from the black hole, beyond which nothing gets out, is the event horizon. However, Hawking made his name in the 1970s when he published a paper showing that black holes don’t just suck stuff up, endlessly - they spew out a beam of so-called “Hawking radiation” as they absorb other matter. That means black holes actually lose mass over time, eventually whittling away to nothing.

Black holes are frustrating, though, because their extreme gravity exposes the major inadequacy in our current scientific understanding of the universe - we don’t know how to reconcile quantum mechanics and general relativity. With general relativity, we can make accurate predictions about objects with certainty, but on the tiny scale of quantum mechanics it’s only possible to talk about the behaviour of objects in terms of probability. When we do the maths on what happens to things that fall into black holes, using relativity gives results that break quantum mechanics; the same goes vice versa.

One of the key things about quantum mechanics is that it tells us information can’t be destroyed - that is, if you measure the radiation given off by a black hole, you should be able to build up a picture of what matter fell into the hole to create it. However, if general relativity holds, and nothing can escape from inside the event horizon, then that should apply to that quantum information - any radiation that’s coming out is, Hawking showed, random. It’s the black hole “information paradox”. Either give up quantum mechanics, or accept that information can die.

Hawking was in the “information can die” camp, until 2004, when it became clear - thanks to string theory - that quantum mechanics held up (and there’s an excellent in-depth explanation of this in Nature that explores this story more fully if interested). There was just one problem - nobody could work out *how* information was getting out of black holes, even if it was happening mathematically.

And, just in case this wasn’t all entirely confusing, it turns out that our best post-2004 theory about what’s been going on gives rise to an entirely new paradox - the “firewall”.

It’s to do with quantum entanglement, where two particles are created that are identical on the quantum level. The way it works isn’t exactly clear yet - it could be something to do with string theory and wormholes - but it means that measuring the properties of one particle will give readings that mirror those found on its entangled particle. It might lead to teleportation technology, but scientists aren’t sure yet.

Joseph Polchinski from the Kavli Institute for Theoretical Physics in Santa Barbara, California published a paper in 2012 that worked out the information paradox could be solved if Hawking radiation was quantum entangled with the stuff falling in. But, due to the limitations of entanglement, if this is true, that would mean that at the event horizon a massive amount of energy was given off by particles entering and leaving.

Hence “firewall” - anything crossing the event horizon would be burnt to a crisp. And even though most scientists, including Polchinski, thought this couldn’t possibly be right - it completely contradicts a lot of the stuff underlying general relativity, for example - nobody’s yet managed to disprove it.

The choice for physicists, once again, was to: a) accept the firewall, and throw out general relativity, or b) accept that information dies in black holes, and quantum mechanics is wrong.

Still with me? Here’s where Hawking’s latest paper comes in.

(That title - “Information Preservation and Weather Forecasting for Black Holes” - might make some more sense too, hopefully.)

Hawking’s proposed solution, building on an idea first floated in 2005, is that the event horizon isn’t as defined as we’ve come to imagine it. He instead proposes something called an “apparent horizon”, which light and other stuff can escape from:

"The absence of event horizons mean that there are no black holes - in the sense of regimes from which light can't escape to infinnity. There are however apparent horizons which persist for a period of time."

Black holes should be treated more like massive galactic washing machines. Stuff falls in and starts getting tossed around, mixed up with other stuff in there, and only eventually is allowed to escape out again when ready. This happens because the quantum effects around a black hole, like weather on Earth, churn so violently and unpredictably that it’s just impossible to either predict the position of an event horizon or expect uniform effects for stuff crossing it. While the theoretical basis, that information is preserved, remains, in practice it's so difficult as to be impractical.

It’s a fudge of an idea, which tries to have its general relativity and quantum mechanics cakes, and eat them, too. Possible weaknesses, as Nature points out, are that it could imply that escaping from black holes is easier than it is in reality. It could also be the apparent horizons are just as much of a firewall as the traditional conception of an event horizon. Hawking's peers have yet to have a go at assessing his idea, so we'll have to wait to see whether the idea has merit - or whether it merely gives rise to yet more paradoxes.

Hawking in Cambridge, September 2013. (Photo: Getty)

Ian Steadman is a staff science and technology writer at the New Statesman. He is on Twitter as @iansteadman.

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The art of the YouTube Poop

What are YouTube Poops and why do we need them now, more than ever?

“The world today doesn't make sense, so why should I paint pictures that do?”

So, allegedly, said Pablo Picasso in a shrewd attempt to justify his love of putting noses where noses don’t actually go. It is imperative that you now hold this profound quotation firmly in your mind whilst you watch this four minutes and 57 second long clip of Arthur – the cartoon aardvark – being tormented by squirrels.

What you have just seen is an example of the art form primarily known as “YouTube Poop” (YTP). Beginning in the early Noughties, this cultural movement is characterised by confusing and shocking edits of Saturday-morning cartoons, video games, and viral videos. Though the Tens have seen the genre decline in popularity, the YTP is, nonetheless, one of the defining innovations of our era.

Those in the Poop community don’t actually like being labelled as artists, as one Yale student found out when he attempted to define them as such on the University’s technology blog. Though they have been compared to Dadaism, YTPs are more vile, violent, and most importantly, nonsensical than most artworks, but this is precisely why they are an asset to our age. In a world where – sorry Pablo, you got nothing on us – absolutely zero things makes sense, it is time for the YTP to have a comeback.

Despite its seeming randomness, the world of YTP is not without its rules. “Poopisms” are the common techniques and tricks used in videos to ensure they qualify as a true Poop. They include “stutter loops” (the repetition of clips over and over), “staredowns” (freezing the frame on a particular facial expression), and the questionably-named “ear rape” (suddenly increasing the volume to shock the viewer). One of the most humorous techniques is “sentence mixing”: forcing characters to say new sentences by cutting and splicing things they have said.

There are also firm rules about what not to do. Panning across a clip without adding another Poopism at the same time is considered boring, whilst using your own voice to dub clips is seen as amateur. By far the biggest barrier that Poopers* face in creating their videos, however, is the law.

Despite what many eight-year-olds on YouTube think, declaring that something is a “parody” in the description of a video does not make it exempt from copyright laws. The video below – regarded by at least two commenters as “the best YouTube Poop” ever – is missing audio 20 minutes in, as the creator was hit by a copyright claim.

Yet even the iron fist of the law cannot truly stop Poopers, who are still going (relatively) strong after the first YTP was created in 2004. YouTube Poops now even have their own Wikipedia page, as well as a page on TV Tropes and a WikiHow guide on how to create them, and for good measure, avoid them.

YouTube Poops have therefore undoubtedly secured their place in history, and whilst you might wander into a comment section to declare “What have I just watched?”, remember that Pablo Picasso once said: “The purpose of art is washing the dust of daily life off our souls.” He almost definitely wasn’t talking about “You are a Sad Strange Little Man” by cartoonlover98, but still.

* The term “Poopists” was rejected by the community for being “too arty”.

 

Amelia Tait is a technology and digital culture writer at the New Statesman.