Stephen Hawking: 'There are no black holes'

[michel123456]

The article from Nature

http://www.nature.com/news/stephen-hawking-there-are-no-black-holes-1.14583

 

Most physicists foolhardy enough to write a paper claiming that “there are no black holes” — at least not in the sense we usually imagine — would probably be dismissed as cranks. But when the call to redefine these cosmic crunchers comes from Stephen Hawking, it’s worth taking notice. In a paper posted online, the physicist, based at the University of Cambridge, UK, and one of the creators of modern black-hole theory, does away with the notion of an event horizon, the invisible boundary thought to shroud every black hole, beyond which nothing, not even light, can escape.

 

 

No comment, simply for info.

 

[jmcnell]

Is hawkings now claiming that black holes don't ultimately devour everything and disappear like he said before? cause I know Leonard Susskind of Stanford gave him a lot of crap for claiming this. Hawkins forsure claimed that all information was destroyed and was never able to be regained.

[Strange]

This is not so much about the information paradox as the firewall paradox (which also comes from some work by Susskind, I believe). He now suggest that, due to quantum effects, the event horizon is chaotic (and kinda porous).

 

Actually, I don't think anyone ever said that black holes "devour everything and disappear". They can, supposedly, radiate energy (Hawking radiation) and so lose mass. But any realistic size black hole will gain mass faster than it is able to radiate it away.

[jmcnell]

Ahh I'm not to in tune with physics but like to keep updated. so correct me the firewall paradox is where space and time stop?

[Rajnish Kaushik]

if there are no black holes then the high power high technology telescope are wrong and that is just a blank space in space where nothing exist

[Strange]

Ahh I'm not to in tune with physics but like to keep updated. so correct me the firewall paradox is where space and time stop?

 

It is one of the conclusions from people attempting to unite general relativity and quantum theory (black holes are a good place to do this because of the extreme conditions). These might be useful:

http://www.nature.com/news/astrophys...e-hole-1.12726

http://www.scientificamerican.com/ar...cal-physicists

Entanglement = Wormholes

Cool horizons for entangled black holes by Maldacena & Susskind (PDF)

[davidivad]

i think that steven was pretty much saying he would bet his career against a firewall (a bit overzealous as this is not really what he did).

i believe he gave three different versions that refuted the firewall idea.

http://arxiv.org/abs/1401.5761v1

 

i do not believe some of the theories that suskind supports but he knows how to break things down for newbies. his lectures are great.

[Implicate Order]

I think it is quite healthy to interrogate the question of whether a 'real' or 'apparent' event horizon exists. This certainly is a crucial boundary to investigate. While GR can mathematically model using simplified assumptions what may occur beyond the event horizon, our ability to physically test these assumptions is permanently hidden to us from the frame of reference of an external observer. As a result, rather than delve into the hidden interior of a gravitationally compact object with hypothetical projections that end in singularities or einstein rosen-bridges etc and lead to other further exotic speculations about our universe (being extended from already flimsy foundations), we need to very carefully examine this apparrent boundary as the likes of Susskind do and take special heed of possible alternate propositions put forward by quantum gravity theorists that at least may be able to be observationally tested as our technology improves.

 

It's fine to mathematically model simple black hole solutions in GR based on the absence or presence of charge and rotation, but without the ability to empirically test the interior regions of black holes, it is difficult to not conclude that such modelling is educated hand-waving at best. When conservation laws such as Information conservation are being tested at the event horizon, it is wise to slow down and closely consider this boundary.

Edited January 29, 2014 by Implicate Order

[Strange]

A handy set of articles from New Scientist to set the context:
http://www.newscientist.com/article/dn24956-hawking-timeline-a-brief-history-of-black-holes.html

[jmcnell]

Ok so the firewall explains what happens to the matter when it falls into the black hole. Instead of being lost it is lost in the form of heat that radiates around the blackhole thus a firewall and ultimately isn't destroyed..

[Unity+]

Ok so the firewall explains what happens to the matter when it falls into the black hole. Instead of being lost it is lost in the form of heat that radiates around the blackhole thus a firewall and ultimately isn't destroyed..

Forgive my lack of knowledge in this area, but I think it is the information that is lost within the black hole. The Hawking radiation(I think) is the result of such lost information to account for such a loss.

[Spyman]

Are black holes no more?

 

To astronomers, the mess of fundamental physics at the event horizon has little to do with the immense gravitational fields produced by these mass sinks at the cores of galaxies, powering some of the most energetic processes in the universe. Astrophysical black holes still happily exist.

 

What Hawking is saying is that, with quantum mechanics included, the notion of a black hole as governed purely by the equations of general relativity, the "classical black hole", does not exist, and the event horizon, the boundary between escape and no-escape, is more complex than we previously thought. But we’ve had inklings of this for more than 40 years since his original work on the issue.

 

In reality, the headlines should not be "black holes don’t exist" but "black holes are more complicated than we thought, but we are not going to really know how complicated until gravity and quantum mechanics try to get along".

http://www.space.com/24478-grey-is-the-new-black-hole-is-stephen-hawking-right.html

 

[I-try]

Did Stephen Hawkins have any other option following the discovery last year of a huge explosion emanation from within our galactic center.

[Strange]

Did Stephen Hawkins have any other option following the discovery last year of a huge explosion emanation from within our galactic center.

 

Can you provide a reference to this explosion? I haven't heard anything about it.

 

p.s. Hawking, not Hawkins.

Edited February 5, 2014 by Strange

[StringJunky]

 

Can you provide a reference to this explosion? I haven't heard anything about it.

 

 

Astronomers led by Prof Joss Bland-Hawthorn from the University of Sydney have found evidence that the supermassive black hole at the heart of our galaxy, known as Sagittarius A*, erupted in a colossal explosion around 2 million years ago. The explosion was so powerful that it lit up a cloud 200,000 light years away.

http://www.sci-news.com/astronomy/science-supermassive-black-hole-erupted-01405.html

[Strange]

Astronomers led by Prof Joss Bland-Hawthorn from the University of Sydney have found evidence that the supermassive black hole at the heart of our galaxy, known as Sagittarius A*, erupted in a colossal explosion around 2 million years ago. The explosion was so powerful that it lit up a cloud 200,000 light years away.

http://www.sci-news....pted-01405.html

 

Ah, I see (I misread the post and thought the explosion was last year!)

 

I don't see how this has any connection to Hawking's work, though.

[imatfaal]

Further to Stringjunky's post - from Joss Bland-Hawthorn's website

 

Galactic Centre explosion. In 2003, Martin Cohen and I discovered a large-scale wind from the Galactic Centre. This preempted the marvellous Fermi discovery of the gamma-ray bubbles in 2010 over the same physical scale (+/-50 degrees!). At the time, we were unclear whether the explosion was driven by a starburst or by a supermassive black hole. But in 2013, we discovered that the Galaxy underwent a full-blown Seyfert phase just two million years ago, i.e. when Homo Erectus walked the Earth! This means that the well-established supermassive black hole at the Galactic Centre (Sgr A*) was blasting bipolar jets at full power only recently in cosmic terms. Of course it's the accretion disk that swirls around the black hole that does this, not the black hole itself. This story had major press coverage in September 2013. The best description of the work is the New Scientist feature article.

 

 

 

 

Ah, I see (I misread the post and thought the explosion was last year!)

 

I don't see how this has any connection to Hawking's work, though.

 

Of course we will pretend that we didn't notice that you "thought the explosion was last year!" and that we already knew about it - light speed would absolutely forbid us from knowing about an explosion last year for a long time as Sgr A* is about 25Klyr away from us. TBH I am guessing/hoping there was a missing or implied "first observed" in that sentence.

Edited February 5, 2014 by imatfaal
unit correction

[Strange]

TBH I am guessing/hoping there was a missing or implied "first observed" in that sentence.

 

Of course. Of course!

[Ender]

I've read Hawking's "solution" to the firewall paradox but many scientists are not really convinced (me neither):

(I'm sorry I don't know how to put the quote thing, hope this is fine)

 

"It is not clear what he expects the infalling observer to see," says Polchinski. "It almost sounds like he is replacing the firewall with a chaos-wall, which could be the same thing." Samuel Braunstein of the University of York, UK, who has waded into the the firewall debate previously, also isn't convinced: "I don't see any evidence which really demonstrates that the thing he is talking about doesn't have a firewall."

 

found: http://www.newscientist.com/article/dn24937-stephen-hawkings-new-theory-offers-black-hole-escape.html#.UvUCLvRDvwh

 

We don't even know what happens at the singularity, maybe information is preserved in some way that still needs to be found, and there will be no firewall.

 

And I also have a question: are we sure that Hawking radiation exists? Has there been a real and undoubted proof? Or is it only a mathematical assumption?

Because on Wikipedia under "experimental observation of Hawking radiation" I just found:

 

Under experimentally achievable conditions for gravitational systems this effect is too small to be observed directly. In September 2010, however, an experimental set-up created a laboratory "white hole event horizon" that the experimenters claimed was shown to radiate Hawking radiation,^[23] although its status as a genuine confirmation remains in doubt.

 

 

from: http://en.wikipedia.org/wiki/Hawking_radiation#Experimental_observation_of_Hawking_radiation

[pantheory]

Hawking seems to enjoy making controversial, “shocking” statements. The supposed claim made by this article is that “there are no black holes.” This claim might be more accurately described as: Black holes may not follow the predictions of General Relativity, according to Stephen Hawking.

 

In particular Hawking proposes that the strong actions (inclusion/ exclusion) associated with a distinct Event Horizon may not exist. Such ideas are not new or unique. Variations of black hole theory from General Relativity have been very common and plentiful including whether black holes have a physical existence at their centers. Such black-hole proposals have been around even before General Relativity, but such modern ideas conflicting with General Relativity are rather unusual for mainstream theorists like Hawking.

Edited February 16, 2014 by pantheory

[iNow]

For those looking for a quick overview without reading too deeply or too technically, this is decent overview of what's being discussed (only intended to supplement the multiple good ones already shared in this thread):

 

 

[Strange]

Hawking seems to enjoy making controversial, “shocking” statements. The supposed claim made by this article is that “there are no black holes.”

 

The "no black holes" claim comes from sub-editors who write headlines, rather than Hawking. His paper makes no such claim.

 

 

This claim might be more accurately described as: ...

 

... quantum effects may make the event horizon more complicated than the simple model of GR alone. That is hardly surprising and is the focus of much current research. Whether Hawking's approach or another one will turn out to be most accurate is something else.

Edited February 17, 2014 by Strange

[pantheory]

 

The "no black holes" claim comes from sub-editors who write headlines, rather than Hawking. His paper makes no such claim.

 

Not surprising. It's a pretty aggressive "contrary" statement. I guessed as much hence my use of the word "supposed" in my statement. In that case the misleading quotes shouldn't be there seemingly implying Hawking's authorship somewhere, i.e. "there are no black holes."

 

. quantum effects may make the event horizon more complicated than the simple model of GR alone. That is hardly surprising and is the focus of much current research. Whether Hawking's approach or another one will turn out to be most accurate is something else.

 

I agree. The true nature of black holes is still up for grabs.

Edited February 17, 2014 by pantheory