Black Hole surrounded by dust.  Credit: ESA / V. Beckmann (NASA-GSFC)

How to Escape From a Black Hole

15 May , 2008

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According to Einstein’s theory of general relativity, black holes are regions of space where gravity is so strong that not even light can escape. And in the 1970’s physicist Stephen Hawking asserted that any information sucked inside a black hole would be permanently lost. But now, researchers at Penn State have shown that information can be recovered from black holes.

A fundamental part of quantum physics is that information cannot be lost, so Hawking’s claim has been debated. His idea was generally accepted by physicists until the late 1990s, when many began to doubt the assertion. Even Hawking himself renounced the idea in 2004. Yet no one, until now, has been able to provide a plausible mechanism for how information might escape from a black hole. A team of physicists led by Abhay Ashtekar, say their findings expand space-time beyond its assumed size, providing room for information to reappear.

Ashtekar used an analogy from Alice in Wonderland: “When the Cheshire cat disappears, his grin remains,” he said. “We used to think it was the same way with black holes. Hawking’s analysis suggested that at the end of a black hole’s life, even after it has completely evaporated away, a singularity, or a final edge to space-time, is left behind, and this singularity serves as a sink for unrecoverable information.”

But the Penn State team suggest that singularities do not exist in the real world. “Information only appears to be lost because we have been looking at a restricted part of the true quantum-mechanical space-time,” said Ashtekar. “Once you consider quantum gravity, then space-time becomes much larger and there is room for information to reappear in the distant future on the other side of what was first thought to be the end of space-time.”

According to Ashtekar, space-time is not a continuum as physicists once believed. Instead, it is made up of individual building blocks, just as a piece of fabric, though it appears to be continuous, is made up of individual threads. “Once we realized that the notion of space-time as a continuum is only an approximation of reality, it became clear to us that singularities are merely artifacts of our insistence that space-time should be described as a continuum.”

To conduct their studies, the team used a two-dimensional model of black holes to investigate the quantum nature of real black holes, which exist in four dimensions. That’s because two-dimensional systems are simpler to study mathematically. But because of the close similarities between two-dimensional black holes and spherical four-dimensional black holes, the team believes that this approach is a general mechanism that can be applied in four dimensions. The group now is pursuing methods for directly studying four-dimensional black holes.

The team’s work will be published in the May 20, 2008 issue of the journal Physical Review Letters.

Original News Source: Penn State Press Release


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Qev
Member
Qev
May 15, 2008 9:32 AM

I’ve always puzzled over the idea that information is ‘lost’ inside a black hole. To an outside observer (eg. the universe), no object ever actually appears to enter a black hole; time dilation effects cause any infalling object’s approach to the event horizon to become slower and its image to become more and more redshifted. So shouldn’t the object always be visible outside the horizon, simply very, very (add a mindboggling number of ‘very’s here) dim?

PP
Guest
PP
May 15, 2008 9:33 AM

So, if one were to accidentally enter a black hole (and survive), s/he could travel far in to the future? But what is “the other side of what was first thought to be the end of space-time” ? It says it’s in the future, but it seems that it’s not purely continuous either.

Silver Thread
Member
Silver Thread
May 15, 2008 9:42 AM

Anyone that thinks Information can be retrieved from a Black Hole has apparently never worked for the Government.

A black Hole warps both Space and Time. Is time compressed by the same mechanism that space is compressed within a black hole?

Within the confines of a black hole does everything happen at once since the dimension of time doesn’t exist to separate it?

Do the X-Rays Emitted from a Black hole originate in what we consider the Present or are they vestiges of a time that has passed or perhaps have they been transported from a time some point in the future?

Tyler Durden
Guest
Tyler Durden
May 15, 2008 1:18 PM

“Anyone that thinks Information can be retrieved from a Black Hole has apparently never worked for the Government. ”

Or worked on a PC running the Windows operating system.

qraal
Member
May 15, 2008 11:42 PM

Hi Silver Thread

Black holes don’t compress space or time, but within the event horizon space-time swap places and all paths end in the singularity – at least in a non-rotating Schwarzschild black hole. The singularity becomes “the future” and is as unavoidable as such.

If the hole is rotating an inner and outer horizon form and things get tricky. But the fall is as inexorable.

Hans-Peter Dollhopf
Member
Hans-Peter Dollhopf
May 15, 2008 11:43 PM
What is the definition of the term “information”, which is used in the context of Black Holes and of this article? What does “information” mean? As long as I do not know, I don’t even get the glimpse of understanding of what this article is dealing with. For example, when a body collides with and so falls into a Black Hole, it is obviously ripped apart previously to it’s disappearing beyond the Event Horizon. So, in analogy, what no one would ever see from Cheshire cat shortly before disappearing inside the Black Hole would be a grin, but a heap of hamburger meat. So, is Abhay Ashtekar talking about the “memory” of that hamburger meat, when he is… Read more »
ferret
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ferret
May 16, 2008 5:04 AM

So if this is true… why are there no black holes from the past spouting junk from then or randomly deposited crap coming out of nowhere? Just something we haven’t recorded yet?

ferret
Guest
ferret
May 16, 2008 5:26 AM

sorry for the double post… i don’t know how to edit previous… anyways, I’m not a scientist… I don’t even have college degree yet… But what if everything was thrown into the same future, at the same place? Could this be said to be like the Big Bang all over again? Could it be an origin for it?

APthebold
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APthebold
May 16, 2008 6:36 AM
As I understand it, “Information” consists of the sum total of matter and energy, and all of the transitional states in between. The last bit is the most critical. Causality in physics requires that you be able to reconstruct what you had before using what you have now. Hawking caused problems when he suggested that the gravity well around a black hole emitted “Hawking radiation”. As the radiation came from around the black hole, and not from the object itself, the information contained in the Hawking radiation has no connection with all of the stuff that fell into the black hole, breaking causality and causing information to be lost. As the article says, Hawking eventually reversed he position… Read more »
uh-huh
Guest
uh-huh
May 16, 2008 6:41 AM

This is all very interesting information, but it’s not what I needed to know. If I’m falling into a Black Hole what do I do to escape. I’m on a schedule so I can’t wait for the end of the black hole’s life – I need out now

APthebold
Guest
APthebold
May 16, 2008 7:01 AM

You’re screwed. One of your parallel reality selves might be lucky enough to not fall in though.

uptwolait
Guest
May 16, 2008 11:07 AM

From the article: “A fundamental part of quantum physics is that information cannot be lost”. Unless, of course, your hard drive crashes.

Ethan Siegel
Guest
May 16, 2008 11:22 AM

Uh-huh, don’t worry. The tidal forces will kill you long before you actually fall into the black hole!

just one answer
Guest
just one answer
May 16, 2008 12:34 PM

As to the X-Rays being emitted from a black hole, they aren’t actually coming from the black hole (as defined by the event horizon) but rather from the disk of dust gases and crud spiraling into it and heating up.

We don’t directly detect the black hole, just it’s effects on everything around it. (Even gravitationally, we just watch other things wobble, warp, or wiz by.)

Jake
Guest
Jake
May 16, 2008 2:43 PM

Just because something exists and you know where it is does not necessarily mean that you can get it.

Besides, there is no evidence to suggest that a black hole has any unusual properties. It is only by assumption that all of the matter accumulated in bodies greater than the size of a star would be not only be luminescent but as luminescent. Rather than trapping light, isnt it more plausible that light simply isnt being produced?

Hans-Peter Dollhopf
Member
Hans-Peter Dollhopf
May 17, 2008 1:36 AM
APthebold Says: May 16th, 2008 at 6:36 am “…’Information’ consists of the sum total of matter and energy, and all of the transitional states in between. The last bit is the most critical. Causality in physics requires that you be able to reconstruct what you had before using what you have now.” Okay, so till Ashtekar it was thought that if a Black Holes comes across our way, “causality” ( which equals information) is sucked into a realm which is forever strictly prohibited for human perception of cause and effect. So the method of falsification is not applicable any longer and that what is does enter a state of metaphysics. Ashtekar now claims that information might “reappear in… Read more »
Hans-Peter Dollhopf
Member
Hans-Peter Dollhopf
May 17, 2008 3:07 AM

APthebold,

in other words: “information” means “knowledge”? Or, the possibility to know what had happened to matter and energy and why it has the current state. And this knowledge is not made impossible by a stay of the observed object inside of a Black Hole.

So maybe we already experience “information” that has been in a Black Hole and which now is already back to normal space-time.

Ry
Guest
Ry
May 18, 2008 12:04 AM
I see some trouble in defining “information” here, but let me just ask how we define “lost.” My understanding of the word is that it simply means something exists where we cannot find it, making it “lost,” an obvious perspectival concept. However, the word, in some context here, seems to be used to define the concept of no longer existing at all. So my question would be, is “lost” defined as information of unknown whereabouts, or information that no longer exists? In essence even something that is said to be “lost for good” still exists somewhere, ironically once something fits this old adage it is said to be lost so far as that it “no longer matters.” I… Read more »
Rock
Guest
Rock
May 18, 2008 7:25 AM

So if Professor Mallett is correct, rotating black holes could send some circulating particles back in time as their speed accelerates beyond the speed of light due to rotating frames. How does this impact the “loss of information” conundrum? Perhaps some information is sent to the far future while other information is sent to the past (but not beyond the moment when the black hole formed.)

SkepticTim
Member
SkepticTim
May 18, 2008 10:14 AM
There seems to be some confusion whenever the word “Information” arises in a physics discussion. Perhaps this will help: According to Wikipedia; “Information itself may be loosely defined as “that which can distinguish one thing from another”. The information embodied by a thing can thus be said to be the identity of the particular thing itself, that is, all of its properties, all that makes it distinct from other (real or potential) things.” Information can be defined by a physical principle called Landauer’s principle, which says that to erase 1 bit of information irreversibly at least k ln(2) entropy should be increased and at least kT ln(2) energy should be consumed, where k is the Boltzman’s constant and… Read more »
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