Stephen Hawking: 'There Are No Black Holes'

ananyo writes "Stephen Hawking has proposed a new solution to the black-hole firewall paradox, which has been vexing physicists for almost two years. The paradox troubles physicists because if the firewall scenario is correct, Einstein's general theory of relativity is flouted. But the classical theory black hole cannot be reconciled to the quantum mechanical prediction that energy and information can escape from a black hole. Now Hawking has proposed a tantalizingly simple solution to the paradox which allows both quantum mechanics and general relativity to remain intact — black holes simply do not have an event horizon to catch fire. The key to his claim is that quantum effects around the black hole cause spacetime to fluctuate too wildly for a sharp boundary surface to exist. As Hawking writes in his paper, 'The absence of event horizons mean that there are no black holes — in the sense of regimes from which light can't escape to infinity.'"

Re:But it is horribly wrong anyway.

[some old guy]

Oh, sure, easy for you to blather about Mr. Smarter-Than-Einstein AC.

Put up your research, with a name, or shut up.

Waiting on the next jump in knowledge

[Akratist]

My sense, in reading a considerable number of articles about astrophysics, etc, is that we are in a period which is awaiting the next big breakthrough in knowledge, along the lines of what Newton and Einstein produced. There are still too many unknowns and ambiguities that need to be resolved by discovering a piece of the puzzle which we don't even know exists yet, and I think people are still trying to get their heads wrapped about quantum physics. That said, I'm not a physicist, just an interested lay person, so I may be wrong in that summation, but it seems many of the discussions occurring these days at least pay a backhanded nod to that sort of notion.

Apparent Horizons, but no Event Horizons

[PvtVoid]

In this picture, there would still be astrophysical black holes in every meaningful sense of the word, i.e. condensed objects from which light would not escape. Such objects would have an "apparent horizon", which can be defined locally by the property that all lightlike geodesics are ingoing.

What these black-hole-like objects would not have is an Event Horizon, which is a global property of the spacetime, and is only defined by the behavior at asymptotic infinity. It's a neat resolution of the whole mess: way more sensible than firewalls.

But it's still just hand-waving -- note that the entire argument relies on AdS/CFT, which assumes the black holes are embedded in de Sitter space, which has a negative cosmological constant and is most definitely not the kind of spacetime we live in. And AdS/CFT is itself an unproven conjecture, although it is supported by many specific example cases. Until somebody comes up with a theory of quantum gravity, this stuff is all guesswork. Caveat emptor.

Re:SubjectsInCommentsAreStupid

[dontbemad]

Didn't know they were opposed.

I've been a staunch believer of both for many years.

Easy solution

[Anonymous Coward]

That was a clever solution. I suggest we apply it to other problems too: Whoops, and there is no cancer. Pop - no more hunger in the world. Zip, and all the pollution is gone.

Best news I've heard in a while.

[wcrowe]

It means all these business idiots will stop saying "event horizon".

Re:Easy solution

[Dunbal]

To be honest, if anything physicists might have been inventing phenomena, dimensions and particles a little to zealously to explain the math. Scaling it back a little bit is not the same as denying the existence of things that are easily detectable and testable, like cancer, world hunger, pollution, etc. There's nothing wrong with a little mythology - it's normal when you're on the edge of the map pushing back the "Here Be Dragons!" fog. But although some explanations and hypotheses could be dead on, it's unlikely that they all are.

Re:SubjectsInCommentsAreStupid

[Anonymous Coward]

Then you have failed to understand at least one of them, or possibly both.

Do you fail at Christianity by dismissing the concept of eternity, or at physics by dismissing the second law of thermodynamics?

Silly drama

[Anonymous Coward]

So basically he's saying the boundary fluctuates so wildly, information behind it can suddenly end up outside it when the boundary jumps back. Of course whatever just ended up outside is now sitting next to a black hole, so the chances of escape are still very low (but non-zero).

If true, this is like saying Newtonian mechincs is wrong and broken now that we know about the relativistic effects, but the reality is difference is so minor we can still follow him for normal tasks.

Taking "there are not black holes" from this is just melodramatic. But then Hawking has been all about showmanship an ignored real science since about 1990. He should have been a reality-TV host instead of a physicist.

Re:But it is horribly wrong anyway.

[RaceProUK]

Newtonian Gravity isn't correct either, we still use it in limited scope. It doesn't mean that Relativity is prevented from the same usage.

But it is still far from correct and the day people finally accept that and move on, maybe some actual research will get done. Dark Matter and Dark Energy are literal blackholes of knowledge that rips Relativity apart in every sense of the metaphor.

There is hardly a contradiction, just you putting meaning where there is none.

You know that building you live in? Built with Newtonian mechanics. That's why it stays up.

And the sat-nav in your phone? That uses general relativity. If it didn't, it wouldn't be able to locate you in the right country, let alone on the right street.

Newtonian mechanics and general relativity have been proven correct many times over. What they are though is incomplete. And there's a mountain of research happening right now to work out why.

Re:SubjectsInCommentsAreStupid

[SirGarlon]

There is huge variety within the Christian religion. Quaker, Roman Catholic, Pentacostal, Amish, Russian Orthodox, Mormon, Coptic, Presbyterian, Christian Scientist, and the newer "non-demoninational" churches all count. It's really hard to characterize them all beyond the very basics.

There are certainly people who call themselves Christian, and reject science. There are also people who call themselves American, and reject religion. It's no more accurate to say Christians are opposed to science than to say Americans are opposed to religion.

Re:SubjectsInCommentsAreStupid

[monkeyhybrid]

So you're saying science can be improved over time, taking new evidence into account to provide a more accurate understanding of how the universe works? That's a good point; it's very much the opposite to religion that continues to hold fast to myth and legend.

Re:But it is horribly wrong anyway.

[Pino Grigio]

I don't think it is, no. But I do think he overstates his case somewhat. For me, the left eyebrow is raised by the need for huge quantities of "dark matter" in order to account for large scale structure of galaxies even though studies of our local region of space show no such matter exists (or is required to explain it). Now OK, if they discover some WIMPs in future I will hold my hands up, but right now being sceptical is the correct position to take on this. And if WIMPs don't exist, well, the predictions of GR won't match observation so at the very least it will need modification.

This is all notwithstanding the fact that physics simply describes the regularities of experience and apparently gives different answers to the same question depending on how that question is posed. It's still amusing to me that mathematics cannot even deal with the 3-body problem in Newtonian Mechanics adequately without resorting to perturbation methods. Then there's the regularisation issue in Quantum Theory, where infinities magically cancel each other out.

I am not a physicist, but I reiterate the need for scepticism everywhere and at all times. It's possible to be sceptical and also have "wow" moments when physicists come up with genuinely new ideas. I do sometimes wonder just how primitive our current bleeding edge ideas will look to our distant descendents.

Re:SubjectsInCommentsAreStupid

[Baloroth]

Scientific reasoning is justification that there is no evidence for a god.

No scientific evidence. It is an improper extension of the scientific method to claim that everything* that lacks scientific evidence therefore does not or cannot exist.

*Obviously, science can make such a claim about many things: anything that you would expect their to be scientific evidence for (i.e. anything natural) can be proven by science to not exist based on a lack of evidence. However, something that is strictly and purely supernatural (which God is pre-eminently) is by the very definition of the word "supernatural" beyond having a nature that science can speak about. Or, in other words, God doesn't have mass, charge, length, time, temperature, or quantity of any kind, and since those are exactly what science deals with, science cannot make any claims whatsoever about God in any way.

Re:SubjectsInCommentsAreStupid

[monkeyhybrid]

It is an improper extension of the scientific method to claim that everything* that lacks scientific evidence therefore does not or cannot exist.

I was very careful to not claim that. To have done so would be stupid. For the same reason, you can not disprove that I am riding a pink unicorn on the moon, although I would hazard a guess that you'd think that be extremely unlikely.

Re:SubjectsInCommentsAreStupid

[Bacon Bits]

Religion is based on myth, legend and anecdotal evidence.

Nonsense. Religion is based on faith. Myth, legend, and anecdotes exist to provide a means to contemplate one's faith. In the context of religion, "truth" means "that which I accept on faith to be true" and nothing more. Unfortunately, dogmatic zealots (both religious and otherwise) project their faith on others. That is the problem with religion.

On the other hand, people treat science as some kind of infallible process. That eventually, an answer will be found if we try hard enough. That science has a monopoly on truth. In reality, science has several fundamental limitations.

1. It assumes everything that exists is observable by humans -- directly or indirectly. It has nothing to say about that which cannot be observed.

2. It assumes everything that exists is measurable by humans -- that it can be somehow quantified and tested. It has nothing to say about that which cannot be measured.

3. It assumes everything that exists is comprehensible by humans. It has nothing to say about that which cannot be comprehended by human intelligence.

We can work around the first two, usually with spherical cows [wikipedia.org]. That last one is a major problem, however. Personally, I think it is the height of hubris to believe that the universe is obligated to exist and behave in a form that humans can observe and measure, let alone that intelligence is capable of understanding. There is no way a dog would understand even basic chemistry. Why do we assume humanity is not so limited?