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?"

Comments

Maybe they read /.

[JeepFanatic]

... and they wanted to get First Post?

Doesn't Count

[ObsessiveMathsFreak]

Does that really count?

No, no it does not.

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.

Re:Doesn't Count

[Beetle B.]

but you may argue that they have produced evidence that supports the theory. No, you can't.

Without knowing the details of both theories, it's hard for me to judge. Basically, if their formalism is more or less isomorphic to Hawking's (without their realizing it) - then all they've done is do Hawking's work over again.

If they used independent formalism to get Hawking radiation, then it's a good sign, and shows that their theory is consistent with Hawking's (and perhaps later someone will link the two).

In either case, they did not produce any evidence. At best, they're saying, "If you look at this our way, it is consistent with what Hawking predicted."

Only numerical simulation

[jayhawk88]

That accurately describes about 90% of theoretical physics doesn't it?

Re:Only numerical simulation

[Thanshin]

That accurately describes about 90% of theoretical physics doesn't it? Yes, the other 10% actually test empirically all their theories. They just keep the TP name because chicks dig it.

Re:First Observation of The Meaning Of Life

[Selfbain]

I think you mean 6 by 9.

What an interesting question

[idontgno]

...though the experiment was only a numerical simulation. Does that really count?

If so, then many slashdotters are no longer virgins.

Slightly OT: Unruh effect

[TeknoHog]

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.

Shenanigans!

[multimediavt]

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.

Re:Shenanigans!

[huckamania]

This is the 'new' science. First you have a theory, then you promote your theory, then someone takes a poll and then it becomes fact.

Computer simulations are acceptable proof in the 'new' science. Even flawed computer simulations are acceptable proof as they prove that the simulations are getting better.

Re:Black holes should radiate anyway

[ExecutorElassus]

yes, but Hawking radiation is somewhat different, and requires no material in the vicinity. It works like this: there are always opposite particles (say, positron-electron pairs) that spontaneously appear at the subatomic level. But in the normal universe, they immediately re-collide, giving back to the local space whatever energy was used to create them. That's a bad explanation (because I'm not a physicist), but it gives a rough picture. At the edge of an event horizon, however, there is a small - though nonzero - chance that one or the other particle will get sucked down the gravity well before it can remerge with its opposite. Thus the one that survived ambles off into space, no doubt pondering its cosmic parthenogenesis. The energy of the particle is - for reasons unknown to me - taken from the black hole. Also, this process steadily accelerates as the black hole continues to lose mass through the process: it eventually pops out of existence in a burst of gamma radiation.

So, it's a little more complicated/interesting than you described; I'm sure it would be even better if someone here could describe it from an actual background in physics, instead of the armchair variety I can muster.

Re:Thinking in circles anyone?

[CmdrGravy]

Not quite, if you imagine the theory as a car then the scientists suspected it might have been a Porsche Cayenne 4x4 and once they had built their simulation ( imagine that as a carwash ) it turned out that it was indeed a Porsche Cayenne 4x4. However the amazing thing was that even though they hadn't considered the driver specifically in their simulation it did indeed turn out the simulated driver was a enormous wanker thus proving beyond doubt the truth of their simulation.

God Exists!

[serutan]

We've got millions of highly vivid simulations!