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Offline blobranaTopic starter

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Stephen (really difficult to understand) Hawking ...
« on: July 17, 2004, 09:16:46 PM »
Hum,
You may have heard that the world-famous author of a "Brief History of Time" has said he and other scientists had gotten it wrong  -black holes may in fact allow `information` (entropy) to escape, and Hawking`s about to reveal all this Thursday...

Read this first!

However another proposed and elegant  solution is to use string theory, a theory that holds that all particles in the universe are made of tiny vibrating strings. Latest research has derived an extensive set of equations that strongly suggest that the information continues to exist -- bound up in a giant tangle of strings that fills a black hole from its core to its surface. The finding suggests that black holes are not smooth, featureless entities as scientists have long thought.

Instead, black holes are stringy “fuzz balls.”
This won’t particularly surprise Hawking and Thorne.
Basically for the newbies here,  Hawking, professor of mathematics and Thorne, professor of theoretical physics, had a wager/bet that information that enters a black hole is destroyed, while Preskill -- also a professor of theoretical physics at Caltech -- took the opposite view.
The stakes were a set of encyclopaedias.

I think that most people gave up on the idea that information was destroyed once the idea of string theory rose to prominence in 1995, It’s just that nobody has been able to prove that the information survives before now

In the classical model of how black holes form, a super massive object, such as a giant star, collapses to form a very small point of infinite gravity called a singularity. A special region in space surrounds the singularity, and any object that crosses the region’s border, known as the event horizon, is pulled into the black hole, never to return. In theory, not even light can escape from a black hole.

(Hehe, basically it's so small that all the information is squeezed out)

The diameter of the event horizon depends on the mass of the object that formed it. For instance, if the sun collapsed into a singularity, its event horizon would measure approximately 3 kilometres (1.9 miles) across. If Earth followed suit, its event horizon would only measure 1 centimetre (0.4 inches). As to what lies in the region between a singularity and its event horizon, physicists have always drawn a blank, literally. No matter what type of material formed the singularity, the area inside the event horizon was supposed to be devoid of any structure or measurable characteristics. And therein lies the problem.
The problem with the classical theory is that you could use any combination of particles to make the black hole -- protons, electrons, stars, planets, whatever -- and it would make no difference. There must be billions of ways to make a black hole, yet with the classical model the final state of the system is always the same. That kind of uniformity violates the quantum mechanical law of reversibility. Physicists must be able to trace the end product of any process, including the process that makes a black hole, back to the conditions that created it. If all black holes are the same, then no black hole can be traced back to its unique beginning, and any information about the particles that created it is lost forever at the moment the hole forms. Nobody really believes that now, but nobody could ever find anything wrong with the classical argument, either. We can now propose what went wrong.
In 2000, string theorists named the information paradox number eight on their top-ten list of physics problems to be solved during the next millennium. That list included questions such as “what is the lifetime of a proton?” and “how can quantum gravity help explain the origin of the universe?”

When you compute the structure of objects that lie in-between simple string states and large classical black holes. Instead of being tiny objects, they turned out to be large. The picture of a “fuzz ball” continued to hold true for objects more closely resembling a classic black hole.
According to string theory, all the fundamental particles of the universe -- protons, neutrons, and electrons -- are made of different combinations of strings. But even as tiny as strings are, they can form large black holes through a phenomenon called fractional tension. Strings are stretchable, but each carries a certain amount of tension, as does a guitar string. With fractional tension, the tension decreases as the string gets longer.
Just as a long guitar string is easier to pluck than a short guitar string, a long strand of quantum mechanical strings joined together is easier to stretch than a single string. So when great many strings join together, as they would in order to form the many particles necessary for a very massive object like a black hole, the combined ball of string is very stretchy, and expands to a wide diameter. The derived formula for the diameter of a fuzzy black hole made of strings is found to match the diameter of the black hole event horizon suggested by the classical model.
The conjecture suggests that strings continue to exist inside the black hole, and the nature of the strings depends on the particles that made up the original source material, then each black hole is as unique as are the stars, planets, or galaxy that formed it.
The strings from any subsequent material that enters the black hole would remain traceable as well.
That means a black hole can be traced back to its original conditions, and information survives... !

which i suppose is the same as what Hawkings is about to announce...that an object falling into a black-hole somehow `changes` the singularity so that the information is `recorded` and eventually radiated away with "Hawking radiation"...er, but without the strings...

OR

A recent idea provides an alternative to black hole singularities is that matter is transformed into a spherical void surrounded by "an extremely durable form of matter known as a `gravastars`...

This would also get around the problem of the tremendous entropy, or information, that a black hole would hold .
So, theory holds that a black hole should have a billion, billion times more entropy sometimes referred to as states, than the star it formed from. Gravastars do not have this problem, as their entropy is very low, and basically sidestep to contradiction known as the “information paradox.”
The matter inside a gravastar would be akin to the Bose-Einstein condensate. It would exist in a vacuum, surrounded by an ultra-thin, ultra-cold, ultra-dark bubble, hence the name gra (vitational) va (cuum) star, or gravastar.

So if the problem is already solved, we can only speculate as to why he has created another solution - we`ll know this coming Thursday...

Offline QuikSanz

Re: Stephen (really difficult to understand) Hawking ...
« Reply #1 on: July 18, 2004, 03:04:12 AM »
@ blobrana,

This may lead to a logical theory for dark matter/energy.

Chris
 

Offline FluffyMcDeath

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Re: Stephen (really difficult to understand) Hawking ...
« Reply #2 on: July 18, 2004, 06:24:30 AM »
@ Stephen


Well, duh! I mean, what were you thinking?
 

Offline Karlos

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Re: Stephen (really difficult to understand) Hawking ...
« Reply #3 on: July 18, 2004, 12:14:00 PM »
The idea that information survives within a black hole was pivotal in one of my favourite Sci Fi novels (the books were based on the oscillating 'big bang' < - > 'big crush' idea).

Basically the books explored the idea that sentient entities have "immortal" souls - their sentience and self awareness persists beyond corporeal death, imprinted on the very fabric of the universe. At the end, within the final collapse of the universe, the sum total of their knowledge etc. becomes a singleton intelligence that determines the pattern of the universe that will follow...
int p; // A
 

Offline Cymric

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Re: Stephen (really difficult to understand) Hawking ...
« Reply #4 on: July 18, 2004, 12:30:24 PM »
@Karlos:

Have you ever read Dan Simmons' Hyperion saga? It has a similar theme to what you describe, although it of course does not end with the big crunch/bang :-).
Some people say that cats are sneaky, evil and cruel. True, and they have many other fine qualities as well.
 

Offline Karlos

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Re: Stephen (really difficult to understand) Hawking ...
« Reply #5 on: July 18, 2004, 12:37:29 PM »
@Cymric

Nope. But I will look out for it now you mentioned it :-D
int p; // A
 

Offline KennyR

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Re: Stephen (really difficult to understand) Hawking ...
« Reply #6 on: July 18, 2004, 07:39:14 PM »
I have to say I liked the Einsteinian interpretation of singularities better. A single one-dimensional point in space, pure, absolute, incorrupt, forever unreachable. A hole ripped in the space-time continuum. Hawking's fuzzy bundle of strings model that still obeys natural laws doesn't sound quite as elegant.
 

Offline blobranaTopic starter

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Re: Stephen (really difficult to understand) Hawking ...
« Reply #7 on: July 18, 2004, 08:22:00 PM »
@KennyR
Whoops,
Hawking's hasn`t announced what his idea is...

The superstring solution and the gravistar solution are two ideas that already solve the main problem of the singularity theory( the non-conservation of entropy, er, just like you can`t destroy energy, type thing) of black holes...

(The sums didn`t add up...big problem)

Hawking will announce his idea this Thursday, but i predict that he`ll somehow show that `hawking radiation` carries away `information` from the black-hole using quantum entanglement   (spooky action at a distance) to transfer the `information` (conserve) back to the rest of the universe...

So, basically, `Virtual particle pairs` are constantly being created in `empty` space....and if they happen to be created near the horizon of the black hole, then one of them can fall in...
Normally, they are created as a particle-antiparticle pair and they quickly annihilate/cancel each other out; so obviously, if one fell into the BH then it's not possible for the other one to `cancel out` , in which case the other one manages to escapes as Hawking radiation.

The particle that fell into the BH is still virtual and must restore its `conservation of energy` by giving itself a negative mass-energy.
The black-hole cancels this negative mass-energy and loses some of it's total Mass and shrinks...
The other particle that managed to escaped contains some of the black hole`s entropy by virtue of being `connected` to the particle inside the black hole...
(well that's the simple version anyway)

The black-hole Mass (solar masses) radiates like a `blackbody` with a temperature of
(6 x 10-8/Mass) Kelvin,
with the total lifetime of a black hole Mass of about:
1071 Mass³ seconds

But who knows what the new idea is...
(er, Hawking does..)


 :-)

Offline Karlos

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Re: Stephen (really difficult to understand) Hawking ...
« Reply #8 on: July 18, 2004, 09:40:24 PM »
I kinda like the idea of a fuzzy string ball :-D Let's see a bloody cat try to unravel that one....

/me envisages startled cat suddenlt crushed to fusion density and spaghettified as it's sucked in...
int p; // A
 

Offline blobranaTopic starter

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Re: Stephen (really difficult to understand) Hawking ...
« Reply #9 on: July 19, 2004, 07:01:14 PM »
yeah,
the string ball (who ever ordered that) is really simple, though (i imagine) the idea of smearing the event horizon of the blackhole with superpositional/entangled particles to `extract` the `information` does sound simpler, er, a bit too simple...

And if that turns out to be what he`s going to say then we should really be asking Why it has taken him 30 years to figure out.... ;)