## Black Holes Not Black After All, Theorize Physicists 227 227

KentuckyFC (1144503) writes

*Black holes are singularities in spacetime formed by stars that have collapsed at the end of their lives. But while black holes are one of the best known ideas in cosmology, physicists have never been entirely comfortable with the idea that regions of the universe can become infinitely dense. Indeed, they only accept this because they can't think of any reason why it shouldn't happen. But in the last few months, just such a reason has emerged as a result of intense debate about one of cosmology's greatest problems — the information paradox. This is the fundamental tenet in quantum mechanics that all the information about a system is encoded in its wave function and this always evolves in a way that conserves information. The paradox arises when this system falls into a black hole causing the information to devolve into a single state. So information must be lost.*

Earlier this year, Stephen Hawking proposed a solution. His idea is that gravitational collapse can never continue beyond the so-called event horizon of a black hole beyond which information is lost. Gravitational collapse would approach the boundary but never go beyond it. That solves the information paradox but raises another question instead: if not a black hole, then what? Now one physicist has worked out the answer. His conclusion is that the collapsed star should end up about twice the radius of a conventional black hole but would not be dense enough to trap light forever and therefore would not be black. Indeed, to all intents and purposes, it would look like a large neutron star.Earlier this year, Stephen Hawking proposed a solution. His idea is that gravitational collapse can never continue beyond the so-called event horizon of a black hole beyond which information is lost. Gravitational collapse would approach the boundary but never go beyond it. That solves the information paradox but raises another question instead: if not a black hole, then what? Now one physicist has worked out the answer. His conclusion is that the collapsed star should end up about twice the radius of a conventional black hole but would not be dense enough to trap light forever and therefore would not be black. Indeed, to all intents and purposes, it would look like a large neutron star.

## Re:wat (Score:4, Insightful)

## Re:Mostly done by 1985... (Score:5, Insightful)

there was always a tiny but measurable probability that trapped light and thus information could escape.Isn't that the same thing as Hawking Radiation? I'm sure Dr. Hawking proposed and submitted work explaining the same thing.

In fact, here is what I am talking about [ucr.edu].

## Re:wat (Score:4, Insightful)

A lot of phenomena in astrophysics are ridiculous, but real.

## Correct: many phenoma in astrophysics are ideas (Score:5, Insightful)

No there are many ideas in astrophysics. We don't know if they are real.

Dark matter? Maybe or maybe not. Dark energy? Maybe or maybe not.

Hawking radiation? It is an idea, it hasn't been proven or disproven.

Speed of light limitation? Probably, but how are neutrinos that have mass going 99.9999% the speed of light? That should require almost infinite energy shouldn't it?

Big bang? A large body of evidence points to a time limit to the beginning of the universe, but cosmic background radiation is the only

strongerevidence of a big bang --- yet this could have another explanation.Cosmic inflation? Could be a non-starter for reasons we currently don't have a handle on --- case in point, it is only happening *far away*. Supernova are used as standard candles, but what if we had different looking supernova 10 billion years ago and our measurements are wrong, therefore inflation isn't happening.

Astrophysics is an emerging field, even now. There are few ways to test all the ideas.

Many of the theories of the exotic blackholes rest precariously on a shaky house of cards, because there is no convenient way to test the ideas.

## Re:wat (Score:2, Insightful)

I'm a professional mathematician and instructor and usually only lurk, but I feel obliged to say this -- you sound like you read a Wikipedia article, poorly, and I advise fellow ./ers not to take this post about Hilbert's hotel seriously.

None of the results are silly. They are all a logical consequence of the axioms of the system. Human beings are quite good a reasoning about finite situations (finitely many objects and finitely many operations on those objects), but humans are regularly surprised by results in situations where there are infinitely many objects or operations. You or anyone else being surprised by the results does not constitute the results silly. A more appropriate emotional response would be to find them interesting or beautiful, if it possible for any emotional response at all to be appropriate. The fact that you find them silly leads me to believe you fear the results, due to your misunderstanding of them.

For the interested ./er, if you really want to understand Hilbert's hotel you need to understand how mathematicians count things. A place to start is:

http://en.wikipedia.org/wiki/Cardinality

http://en.wikipedia.org/wiki/Bijection

(Wikipedia, I know.)

## Re:wat (Score:2, Insightful)

Black holes aren't "infinitely dense" because that is ridiculous

You're misinterpreting the meaning of "infinite" here.

You're assuming density measurement has an infinite value. Like "How many dollars are there?" Well, you could have any number of dollars from 1 to infinity.

That's not how density is measured.

Another type of measurement is "What angle is the corner of that triangle?"

That could be anywhere from 1 to 359 degrees (rounding to whole numbers)

It's kind of like a percentage.

Infinite density would be like saying the angle is 360 Degrees. That breaks the triangle. The angle is effectively infinite.

Mass, density, momentum, time, etc... are all treated like geometry when you get into relativistic effects.

You can't exceed the speed of light because that to would break the geometry of the system. Once you hit the speed of light, you again are doing the equivalent of making one of the angles 360 degrees.

The "Triangle" of this system is Speed, time and mass. So for speed to exceed the speed of light and therefor be the "360 degree angle" of this triangle, the other two angles... time and mass, must be 0. Therefor time stops, and the moving object must be massless. Does that make more sense?

At least thats how I've always understood it.

## Re: wat (Score:5, Insightful)

What if ONLY infinities exist? After all, what could lie outside them?

In fact, there'd be only "Infinity" all sense of plural or singular being reduced to non-statements.

Wow.

Have you ever REALLY looked at your

fingernails, man?## Re:wat (Score:4, Insightful)

Who says I was talking about a planar triangle? http://en.wikipedia.org/wiki/S... [wikipedia.org] :-p

Ok, I was... but the oldest geometry typo since the pyramids does not invalidate relativity.

## Re:wat (Score:5, Insightful)

Define a circle.

Do circles exist in reality, or only in mathematical models?

What do engineering artifacts, as approximations of circles, bear in relation to "real" circles?

Are infinities actual, or are they mathematical descriptions for mental extrapolations based in observed phenomena?

Do mathematical models display consistency with real, observable phenomena or with any mental extrapolation? Which one is more "real"? Why?

Mathematics can only describe the set of perceptions, IMHO. When they describe unperceived "realities" they enter the realm of fictions or metaphysics.