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First "Observation" of Hawking Radiation
KentuckyFC writes "Italian physicists are claiming the first observation of Hawking radiation, but not from a black hole. Instead they've spotted it streaming from a sonic horizon in a Bose Einstein Condensate (abstract on the arXiv). That's consistent with previous predictions but they're claiming the 'first' even though the experiment was only a numerical simulation. Does that really count?"
... and they wanted to get First Post?
and you get a black hole. but, don't feed it.
If people can get past, can they get future? Best way to confuse a stoner
A numerical model is little more than a highly specific and round off error prone implementation of existing analytical results. All these guys have done, at most, is shown the correctness of Hawking's analysis. If that.
May the Maths Be with you!
That accurately describes about 90% of theoretical physics doesn't it?
6 * 7
It's just a numerical simulation, but everybody knows it counts anyway.
I am sorry, but I don't buy it... You have a theory how the world behaves. You do a numerical simulation based on that theory, and amazingly, it proves true. And you consider that a proof of your theory?
I guess I will make a theory stating that fairies exist... simulate that in a computer, and when fairies appear in my simulation I write an article that I have observed fairies. Mmmmhh, this certainly sounds like proving ID.
If so, then many slashdotters are no longer virgins.
Welcome to the Panopticon. Used to be a prison, now it's your home.
My first thought from the headline was Unruh effect. It's a kind of Hawking radiation you can get in a particle accelerator. It just happens that with black holes, the acceleration is due to gravity, but other sources of acceleration also work. There are huge decelerations from c to nearly 0 at heavy ion collisions, for example.
I first heard of the effect when some fellow physicists were considering the idea of tiny black holes created in particle physics experiments. It turned out that the presence of Hawking-like radiation doesn't necessarily mean a black hole.
Well, it also turns out that this has nothing directly to do with the article, but might be +i, interesting nevertheless.
Escher was the first MC and Giger invented the HR department.
If you consider the cusp of the gravity well of the earth to be a simplistic representation of the event horizon then:
an object travelling inside the well is doomed to never escape without additional energy.
it will spiral to its death after some time period.
If two objects at this same point collide and explode, then some of the matter will have gained additional energy and will escape the gravity well, the rest of the body will spiral to its doom.
liqbase
It's just a simulation... hawking radiation hasn't been observed in real life yet.
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How long until they "observe" a Fry, er, Hawking Hole? I could have swore I "observed" one on TV.
I'm sorry, but I'm with the "no way this counts" camp. Theories have to be tested in the physical world to be proved. Theoretical physics included folks. That's why we have supercolliders and Z-machines, duh! Numerical analysis can help predict physical behavior but it is not law until it is proved in the real world. Sorry guys.
StoneCypher is Full of BS
and they altered the phenomena by observing it.
We've got millions of highly vivid simulations!
In either case, they did not produce any evidence. If they have correctly use an independent formalism to verify Hawking radiation, they may not technically have "produced" any new evidence, but it means that all the existing evidence that backs the independent formalism, now also counts as evidence towards Hawking radiation.
[ I haven't read the fine article either. ]
The story is grossly distorted -- what a surprise. I was going to say that at least it was distorted by author of the linked-to news item, rather than by the /. submitter, but now I see they seem to be the same person ("KFC" and "KentuckyFC").
The abstract that is linked to merely claims "numerical evidence", not "first observation", and to get from that unobjectionable claim to the more sensational false accusation, one must distort the paper itself ( http://arxiv.org/pdf/0803.0507v1 ), which says:
So for one thing, they never claimed "first observation", they said "first independent proof", which is sharply different.
For another thing, they softened even that claim; they said "our observations [of the simulation] can be considered" proof, not that it is proof.
At any rate, it's interesting in general; they're talking about predictions that Hawking-Unruh radiation might be found in many settings unrelated to domains involving gravity or acceleration, and that their simulation might be an independent confirmation of those predictions.
Professional Wild-Eyed Visionary
This is far from proof. But I would not really be surprised, just at an intuitive level, if Hawking radiation can be found at ANY type of horizon. Hawking radiation itself was predicted by a post-doc whose name I forget, promptly forgotten for several years, then it was picked up and championed by Hawking. Hawking himself wasn't the one who made the original connection between entropy and certain horizon equations, although he did start the process in motion with a proof that the area of the event horizon cannot decrease.
It sounded incredibly far-fetched at the time -- just because the equations look similar can't possibly mean there is radiation, can it? And yet it was true. I'm not surprised at all. Anywhere you have a horizon and also a law which prevents that horizon's area from decreasing with time, you are probably going to see black body radiation.
So they have 'observations' of a 'simulation' of a Bose-Einstein Condensate which 'theoretically' would behave with sound waves similarly to the way a black hole is 'theorized' to behave with regard to particles that pop into existence all the time and it's proof of Hawking radiation? There are just too many theoretical leaps here to give it any weight. If these sound waves were ACTUALLY observed in a real-world experiment and not a simulation then that would be a step closer. Can't they just make a simulation of the event horizon of a black hole?
I'm prepared to be corrected, but doesn't that count as a prediction rather than an observation?
Athy, athier, athiest.
A validation consist of comparing the predictions made with one formalism with actual measurements, and see that they match.
Verifications are not as strong as validations, but none the less quite useful. Typically it works the other way around though, we verify a numerical model against one or more analytical solutions. If they match, we gain trust in that the numerical model also can make correct predictions for the cases where no analytical solution can be found. Of course, we would like to eventually add actual validations. But that might be much more time consuming and/or expensive. I work in agricultural science, an experiment takes a year. We would like to sort out as many bad models as possible before starting that, hence we always use verification as the first step. [I shouldn't complain, the people in forestry are much worse of. ] like you or I might observe the existence of Martians by looking at the right Bugs Bunny cartoon Bugs Bunny cartoons are not a very strong formalism. If they predicted Hawking radiation by hawing a Bugs Bunny cartoonist draw what he would think it might look like, that would not lend much credibility to the theory.
It all depends on the formalisms used.
I hope so, because that would make me a fighter pilot, a train driver, and a theme park owner this week alone. I have after all used MS flight sim, MS Train sim and Trains, and Rollercoaster Tycooon. Oh I almost forgot I own a motorboat and a jet ski (Ship Sim 2008. We didn't say it had to be a GOOD simulation did we?). I'm so good I can ram a boat at high speed in a jet ski, duck under it instead of dying, and come out the other side!!! Come to think of it I rock, but only if simulations count!
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That's the problem with computer simulations that are unsupported by real observations: you never know if there's a problem with your input data, a bug in your simulation program, or a serious weakness in the theory you are simulating, or some combination of all of these. So it's hard to believe your outputs until you can check them against a real measurement.
Pfft.. I've detected Hawking Radiation spewing from the sonic horizon of my Bose Wave Radio for years!
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