Stuff that falls into a black hole is gone forever, right? Not so, says Stephen Hawking.
“If you feel you are in a black hole, don’t give up,” he told an audience at a public lecture in Stockholm, Sweden, yesterday. He was speaking in advance of a scientific talk today at the Hawking Radiation Conference being held at the KTH Royal Institute of Technology in Stockholm. “There’s a way out.”
You probably know that black holes are stars that have collapsed under their own gravity, producing gravitational forces so strong that even light can’t escape. Anything that falls inside is thought to be ripped apart by the massive gravity, never to been seen or heard from again.
What you may not know is that physicists have been arguing for 40 years about what happens to the information about the physical state of those objects once they fall in. Quantum mechanics says that this information cannot be destroyed, but general relativity says it must be – that’s why this argument is known as the information paradox.
Now Hawking says this information never makes it inside the black hole in the first place. “I propose that the information is stored not in the interior of the black hole as one might expect, but on its boundary, the event horizon,” he said today.
(Score: 0) by Anonymous Coward on Wednesday August 26 2015, @01:50AM
Way I see it, these speculations about black holes don't deserve the publicity they get - they might as well be arguing how many angels can stand on a pin heads. An observational verification of some such hypothesis? Now that is something worth reporting.
(Score: 2) by edIII on Wednesday August 26 2015, @02:02AM
Exactly. We went to the moon and finally figured out it wasn't made of cheese. Now we don't go back.
Similarly, one day we will visit the places where the black holes are, and feel intensely foolish that we obsessed so much over rather simple intergalactic off-ramps. It will be argued over while playing that game with the pegs at the Cracker Barrel one light year away.
Technically, lunchtime is at any moment. It's just a wave function.
(Score: 0) by Anonymous Coward on Wednesday August 26 2015, @02:22AM
Or you'll underestimate the gravitational strength and it will killllll yooooooo
or freeze you on the event horizon, a not so bad fate according to Hawking
(Score: 0) by Anonymous Coward on Wednesday August 26 2015, @02:22AM
“If you feel you are in a black hole, don’t give up,” he told an audience at a public lecture in Stockholm, Sweden, yesterday.
That's probably true, but I would prefer to hear Dr. Hawking talk about physics, not offer me career advice.
(Score: 0) by Anonymous Coward on Wednesday August 26 2015, @02:33AM
That's probably true, but I would prefer to hear Dr. Hawking talk about physics, not offer me career advice.
That's probably true, but I would prefer to hear Dr. Hawking talk about physics, not pretend to be Douglas Adams.
Don't Panic -- ftfy
(Score: 0) by Anonymous Coward on Wednesday August 26 2015, @09:14AM
"You're basing all this on what Stephen Hawking says, and the fact is, he's subject to interference from minicabs."
-- Jeremy Hardy, QI 1x04
(Score: 2) by HiThere on Wednesday August 26 2015, @02:53AM
According to general relativity, as I understand it, you aren't supposed to notice any difference at any particular point as you fall into the black hole. Crossing the Schwartzhild boundary is supposed to be undetectable. So I don't see how this proposed solution can be compatible with general relativity. Of course, it might happen *before* you cross the boundary, but in that case it should be detectable.
Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
(Score: 1, Informative) by Anonymous Coward on Wednesday August 26 2015, @03:31AM
According to general relativity, as I understand it, you aren't supposed to notice any difference at any particular point as you fall into the black hole.
You might notice other stuff though:
https://en.wikipedia.org/wiki/Spaghettification#Inside_or_outside_the_event_horizon [wikipedia.org]
(Score: 0) by Anonymous Coward on Wednesday August 26 2015, @09:24AM
Well, if you fall into a black hole, you certainly slightly disturb the black hole's gravitational field. The shape of the horizon is determined by the gravitational field. I guess that's the mechanism how the information about you gets stored in the horizon.
(Score: -1, Offtopic) by Anonymous Coward on Wednesday August 26 2015, @02:59AM
I read "Proposes" as "exposes", almost vomited all over the keyboard.
(Score: 0) by Anonymous Coward on Wednesday August 26 2015, @09:26AM
If that already makes you vomit, I guess dyslexia is the least of your problems.
(Score: 4, Informative) by MichaelDavidCrawford on Wednesday August 26 2015, @04:24AM
The radius of the event horizon is large for more-massive black holes. For a supermassive black hole the gravitational pull on your feet is quite close to that on your head even when diving straight in. You wont feel a thing, it will be just like when my friend walked onto a patch of quicksand at guantanomo bay.
You will eventually be stretched along the direction of the field but not until you are much closer in.
From the reference from of the unlucky astronaut I dont see any reason that space just within the event horizon will be in any significant way different from the space just outside it.
For example I expect you and I are inside a black hole right now. That black hole was a star in a universe that itself is inside a black hole.
Yes I Have No Bananas. [gofundme.com]
(Score: 2, Funny) by dexcheque on Wednesday August 26 2015, @11:23AM
It's black holes all the way down!
(Score: 0) by Anonymous Coward on Wednesday August 26 2015, @04:44AM
you fall into a black hole and no one is there to see it. Do you even exist?
(Score: 0) by Anonymous Coward on Wednesday August 26 2015, @09:37AM
If I fall into a black hole, I am there to see it, am I not?
(Score: 2) by VortexCortex on Wednesday August 26 2015, @11:17AM
If I fall into a black hole, I am there to see it, am I not?
Yes, you are naught.
Consider what Hawking is saying: You fall into the black hole. As you reach the event horizon time itself stops, we know spacetime are intertwined. So, rather than being stretched in the traditional spaghetti sense one may become stretched similar to how a 3D image is stretched across a 2D film. This needn't mean local space appears any different to you, the new "holographic" you could feel as if falling when you're really just being distributed. Many people get caught up thinking about the black hole and forget that the singularity is not the interesting part, the interesting part is the rest of reality around the black hole. How things work at the (quantum) physical extremes tell us about the rest of reality. If you (or your information) is stretched into a hologram at the black hole's event horizon then this implies "normal" spacetime is also holographic -- Meaning the dimensions of width, height, depth, themselves may be illusory. If the dimensions can be bent such that the dimension of time stops, then they can also be bent such that width, or height, stops. Indeed, when you accelerate something fast enough it requires increasingly more energy to accelerate -- As acceleration stops your dimensions change, similar to falling into a black hole but the in the inverse.
This is all rather simplified, but what I mean to say is space at the black hole's event horizon is no different than the space at the end of your nose. We are all the same universe, there is no dividing line in nature between yourself and your immediate surroundings or the super massive black hole at the center of the galaxy. Self is an artificial construct, there never was a "you".
(Score: 0) by Anonymous Coward on Wednesday August 26 2015, @12:25PM
"there never was a "you"."
Of course there was never an I. It's always been we. We're all just a bunch of holobionts.
(Score: 0) by Anonymous Coward on Wednesday August 26 2015, @12:31PM
But can you hear it?
While you maybe a super being that can survive the process of falling into a black hole to maybe see it I might not be able to. but our question, as a holobiont, is will some of my inner bacteria survive it? While I don't think they have 'eyes' to 'see' that part of me certainly worries about its survival and is here compelling me to type this question against my will. It wants an answer. Perhaps your inner holobiont side will persuade you to respond.
(Score: 4, Interesting) by bob_super on Wednesday August 26 2015, @05:37AM
> what happens to the information about the physical state of those objects once they fall in.
> Quantum mechanics says that this information cannot be destroyed, but general relativity says it must be
The answer is "flattened and/or crushed".
For someone unfamiliar with the massively complex details of the mathematical theories about the black holes, it seems to me that the immense local gravity of having a star the size of a pinhead or golf ball doesn't need extra "information destruction" explanation.
In a nutshell: take a big space rock: throw it at a really big planet, supermassive-star-weight. Crunch. Space rock is part of planet. Gravity wins, nobody argues that the information of the rock's matter vanishes.
Send the same rock to a star of the same weight. Frootch! Rock gets crushed and carbonised and its atoms part of some chemical or nuclear reaction, maybe plasma... nobody argues that the quarks vanished.
Turn the star off and let it collapse to the size of a marble under its own weight, straining the human rules of physics. send rock. Plop! Rock gets crushed, its atoms and/or quarks learn to be a lot cosier. Superdense state, even photons get confused, its it even still mass or energy?
Tell the idiot that I am why the rock's matter's information is "destroyed". From the standpoint of the black hole, matter/energy is added (and surely transformed). We can't explain the new state because we can't observe it to get even the first piece of information on which theory could possibly be the least absurd. But I don't get why the observable concept "lots of mass in unknown state swallowed one more thing passing by" becomes a mess of wormholes and quantum information continuity...
(Score: 0) by Anonymous Coward on Wednesday August 26 2015, @09:33AM
The point is that nothing can cross the event horizon from the inside. So everything that passes from the outside is forever hidden inside. So at least in the traditional view, this means that the information is no longer available outside, because to be available outside, it would have to pass the event horizon from the inside, which is not possible.
However now we have Hawking radiation, which means that the black hole evaporates. But as Hawking radiation is created outside of the black hole (otherwise it could never escape it), it cannot carry the information about the stuff in the inside either. The information remains locked in the inside of the black hole.
But Hawking radiation means the black hole will completely evaporate in finite time, that is, after some finite time there will not be a black hole any more. But the information in the black hole didn't ever leave it. So if the black hole is now gone, where is the information?
(Score: 2) by bob_super on Wednesday August 26 2015, @04:13PM
Thanks for the answer.
My follow-up question is "when does a black hole which is losing mass stop being a black hole?"
It seems to me that the information remains in the black hole as it's losing mass (contingent on Hawking Radiation actually being real), and then at some point the "overwhelming gravity crushes particles and prevents light from escaping" part of being a black hole stops being true.
A simple google search doesn't answer the question: "is there really a state of matter such that a black hole made of one particle still has an event horizon, allowing it to emit that last bit of HR that will negate its existence?" If yes, i'm puzzled. If no, the sum of the trillions of information bits that constituted the matter in the black hole is still present in the remaining things which transform back into other things when the gravity falls below the black-hole-sustaining threshold.
(Score: 2) by AnonymousCowardNoMore on Wednesday August 26 2015, @04:20PM
The information is not what YOU, personally, can tell. The information is what THE UNIVERSE can tell. It is what could be told in principle by an observer with way too much time on his hands, omniscience and more grant money than the US DoD budget. It is all that can be told because there is nothing more to tell, is what I'm trying to get across here.
If you drop a rock on the moon at solar system escape velocity, it makes a crater, a cloud of dust and gas and a field of debris. Knowing where everything and what it's doing, including everything that it's interacting with such as the sun, planets, etc., you could in principle calculate the trajectories backwards and work out what happens. You can't know these things, so you can't work it out, but the universe nonetheless holds the information (in a way which gets more complicated but still analogous when quantum mechanics is taken into consideration).
That's what the debate is about.