New research by scientists at the University of York gives a fresh perspective on the physics of black holes.

Black holes are objects in space that are so massive and compact they were described by Einstein as "bending" space. Conventional thinking asserts that black holes swallow everything that gets too close and that nothing can escape, but the study by Professor Samuel Braunstein and Dr Manas Patra suggests that information could escape from black holes after all.

The implications could be revolutionary, suggesting that gravity may not be a fundamental force of Nature.

Professor Braunstein says: "Our results didn't need the details of a black hole's curved space geometry. That lends support to recent proposals that space, time and even gravity itself may be emergent properties within a deeper theory. Our work subtly changes those proposals, by identifying quantum information theory as the likely candidate for the source of an emergent theory of gravity."

But quantum mechanics is the theory of light and atoms, and many physicists are skeptical that it could be used to explain the slow evaporation of black holes without incorporating the effects of gravity.

The research, which appears in the latest issue of *Physical Review Letters*, uses the basic tenets of quantum mechanics to give a new description of information leaking from a black hole.

Professor Braunstein says: "Our results actually extend the predictions made by well-established techniques that rely on a detailed knowledge of space time and black hole geometry."

Dr Patra adds: "We cannot claim to have proven that escape from a black hole is truly possible, but that is the most straight-forward interpretation of our results. Indeed, our results suggest that quantum information theory will play a key role in a future theory combining quantum mechanics and gravity."

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**More information:**
Black Hole Evaporation Rates without Spacetime, *Phys. Rev. Lett.* 107, 071302 (2011) DOI:10.1103/PhysRevLett.107.071302

**Abstract**

Verlinde recently suggested that gravity, inertia, and even spacetime may be emergent properties of an underlying thermodynamic theory. This vision was motivated in part by Jacobson’s 1995 surprise result that the Einstein equations of gravity follow from the thermodynamic properties of event horizons. Taking a first tentative step in such a program, we derive the evaporation rate (or radiation spectrum) from black hole event horizons in a spacetime-free manner. Our result relies on a Hilbert space description of black hole evaporation, symmetries therein which follow from the inherent high dimensionality of black holes, global conservation of the no-hair quantities, and the existence of Penrose processes. Our analysis is not wedded to standard general relativity and so should apply to extended gravity theories where we find that the black hole area must be replaced by some other property in any generalized area theorem.

## Husky

## antialias_physorg

http://arxiv.org/...26v2.pdf

## JustCurious

## rawa1

## gwrede

The rest is mere conjecture, except for the part with no-hair.

@JustCurious: Depends on who you ask. If they believe in positive gravity for both, then the black holes will merge, and when eventually the "cores" meet and violently explode, they will anyhow be within the event horizon. Unless of course, we take literally the bit about matter being squeezed to zero volume. Then they obviously can never meet. With finite volume they will annihilate, instantaneously causing an undoing of the space curvature, leading to dispersal of the event horizon.

With negative gravity of antimatter, you'll get another equally off-the cuff "opinion", served as the truth. -- Anyhow, every person (or scientist) will tell you a different story.

## antialias_physorg

I'm not sure this follows as the emission of information (or mass) is dependent on very specific circumstances which need not be met:

1) Particles split into two within the ergosphere

2) One of the parts may have negative energy

If the part with positive energy escapes angular momentum can be reduced (note that this mechanism does not constitute a reduction of the event horizon but only of the ergosphere until it coincides with the event horizon and the engular momentum of the black hole becomes zero. From then on only Hawking radiation will reduce the size of a black hole)

Now while 1) is probably a frequent occurence there is no indication why 2) should be an asymmetric case (i.e. why in a majority of cases the part with the negative energy should be the one that stays inside).

## rawa1

## JustCurious

## Raygunner

I'm just a layman trying to understand some of this - please excuse my ignorance.

## Egleton

My understanding of this is that gravity is not a primary

"thing", but that it is a creation of quantum mathematics.

It is good to know that there is still stuff we dont know. It gives me hope that we might be able to truely be able to get out of the gravity well.

## antialias_physorg

In this case it's not about associating input with output but about getting anything back from the black hole at all. The article (and Hawking radiation) shows that over time you can get more out than you put in - which means that there can be a net information flow (apparently *) from the black hole to the outside universe (in contrast to the usual notion that 'nothing' can escape a black hole).

* 'Apparently' because even Hawking radiation does not originate from within the event horizon.

## Techno1

This would be true in classical mechanics, relativity, and quantum mechanics.

Just look at the classical kinetic energy formula:

Ek = (1/2)mv^2

If you change your angular momentum, you will change your instantaneous linear velocity, at least in most cases, with respect to some reference point, in this case the black hole.

If the velocity went up the energy went up, and the energy had to come from the black hole.

Moreover, since in relativity mass itself goes up with velocity, the particle actually robs "energy" from the black hole on BOTH the "m" variable and the "v" variable.

We ordinarily neglect relativity of mass for small velocities or changes in velocity, but the reality is ANY change in velocity represents a non-zero change in mass.

## Raygunner

I guess the word "information" and in context with a black hole is somewhat misleading, at least to me. Particles are considered information? I can see this but it is stretching the meaning a good bit. What is not clear is the point they are trying to make. I guess if you could monitor a BH from beginning to end, count ingoing and outgoing particles (good luck with that), and come up with a figure that shows proper I/O balance... well that seems impossible. It's all theory anyway and I can see where they have to try and work things out the best that they can.

## LuckyBrandon

It would suck!

## Burnerjack

Is it possible that a BH is hollow with incredible mass surrounding a pure energy core? My imagination tells me that at some point the matter approaching the singularity is literaly crushed out of existence similar to total anihilation.

Also, what might the rpm just outside the singularity be?

## yep

The Schwarzschild solution and its implications for gravitational waves Stephen J Crothers

http://www.holosc...talk.pdf

## hush1

He demands the underlying math contain no calculation errors.

A demand that is unacceptable for the astrophysical society.

## Gawad