Physics/astronomy dopers, is this bad reporting, plausible, BS, or have we all been fooled, for years, into believing in phlogiston again?
That paragraph does rather seem to contradict itself.
The paper never says anything about a black hole being impossible. Just that the current stellar collapse model doesn’t pass the pencil test to form a black hole.
I read a paper on hypothetically forming an artificial black hole. The problem is that you must cram an incredible amount of mass-energy into the black hole before it is even stable enough that it won’t evaporate instantly. This makes creating an artificial one incredibly difficult. Were you to simply try to squeeze mass together, the moment it passes the threshold to become a black hole, hawking radiation is so intense that the black hole instantly evaporates.
The proposed method that has a chance of working is to fire relativistic rods that have to total about 1 million tons of mass-energy. The rods slam into each other and create a compressed point of matter so dense that it won’t evaporate from hawking radiation. The problem is that there might not be enough mass in our solar system to build the apparatus needed to do this. (even if you had the self replicating robotics, etc, you would need in order to even consider a project like this)
The article is explicit:
It doesn’t even begin to answer the question of what it is that is seen at the centers of galaxies if that is true.
I suspect a huge gap between the paper and the report, which is merely a reprint of the UNC press release.
Well their numerical simulations suggest that as the star collapses Hawking radiation ramps up effectively reducing the star’s mass and slowing the collapse. Paper is here - [1409.1837] Back-reaction of the Hawking radiation flux on a gravitationally collapsing star II
The problem, aside from trying to explain existing phenomena we call black holes is that their code fails just at the point where it looks like neat things happen. It’s a numerical simulation so extreme conditions are going to involve extreme reactions.
Wait a minute… both linked articles claim that she’s reconciled relativity and quantum mechanics, and we’re supposed to be excited about whether or not black holes exist?
I think I’ll write my own news article. Headline: “Isaac Newton enjoyed a tasty apple” and then, two paragraphs from the end, I’ll comment: “He also came up with the theory of gravity and some fancy math that uses squiggly lines.”
I’d be interested in knowing if they have a specific emission profile that could be reconciled with actual stellar collapses.
Gottfried Leibniz invented the (use of) squiggly lines, and was kind of concurrent with Issac Newton as far as the overall methodology. Newton used some sort of “dot notation” that never became popular.
Just to be clear, both the paper in question and the comments above (i.e. Grey’s quote), seem to be stating that Hawking Radiation is not emitted by a black hole per se but, rather, arises from the intense gravitational field just outside the event horizon. Have I got that right?
If so, does that imply that the detection of Hawking Radiation would not necessarily imply the existence of a black hole (i.e. it could come from any very strong and compact gravitational field, and not just from a BH)?
Thanks!
Maybe black holes don’t exist now because it would take an infinite amount of time for them to collapse to become one?
What do you mean by “seen” in that sentence. I think what you mean is “inferred” from certain measurements (very likely manifest as a numerical printout), via a lot of theory and some quite complex math.
This is what I meant, but as a professional writer I used one word instead of twenty. 
Dot notation is still in use in mechanical and electrical engineering.
It’s not being published in a peer reviewed journal, or even being presented at a legit conference. In other words, it’s not Real Science ™.
Also, black holes really suck.
One thing that struck me is the article seems a little disingenuous, in that it omits theories that can account for some of the paradoxical nature arising from black holes, like Susskind’s Holographic Principal in regards to “information loss.”
"Conservation of information " ? What ? where does that idea come from ? Well its not like information is conserved elsewhere… its not like a “conservation of energy/matter”…
Nothing could be known about the insides of the blackhole…and they only exist where “the laws of physics breaks down” . There’s no predicting what the result of a break down of the laws of physics will be… The laws of physics allow us to predict… If we could predict the insides of a black hole, then the laws of physics still apply… the laws told us a prediction, they still hold !.
The problem is the complete lack of information about the insides of dark patches.
Meanwhile, they talk of dark matter and dark energy. Whats to say that a black hole isn’t just dense dark matter ? Matter which does not emit light… Matter which explains the gravity of a galaxy… I thought that was black holes… now its dark matter… I guess dark matter is the new name for the old concept… “the centre of the galaxy appears to be very dense, but not correspondly brighter”.
How to tell the difference between dark matter and a black hole ?
If some insubstantial particle or wave, eg neutrino’s, gravity waves could be traced … eg by their path through ? but then they’d have to make light somehow… in order to show there path… some environment where their path shows up like bubbles in a bubble chamber…
The connotations of ‘seen’ and ‘“inferred” from certain measurements (very likely manifest as a numerical printout), via a lot of theory and some quite complex math’ are vastly different. ‘Seen’ implies that there is really no room for any doubt about it, and opinions are most unlikely ever to change. What I said brings out the reality that there is actually enormous scope for reasonable doubt on all sorts of grounds, and opinions are quite likely to change.
No, nobody has ever seen black holes at the center of galaxies. What have been considered our best theories, up until now, imply that they should be there, but what are considered our best theories changes all the time, and the whole point of this thread is that the theories relevant to black holes may be in the process of changing right now.
Neither peer reviewed publication nor conference presentation have any bearing on the question of whether a scientific claim is actually true or false.
It’s like a movie not being screened for critics: never a good sign.
Also, many or maybe even most scientific papers, including those exhaustively peer-reviewed and vetted, turn out substantially or even entirely incorrect.
This story has B.S. written all over it.
We can safely continue accepting that black holes exist.
This sounds a whole lot like the ‘you weren’t there!’ argument that creationists are so fond of. Everything is ‘inference’. Everything.