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First Acoustic Black Hole Created
KentuckyFC writes "One of the many curious properties of Bose Einstein Condensates (BECs) is that the flow of sound through them is governed by the same equations that describe how light is bent by a gravitational field. Now, a group of Israeli physicists have exploited this idea to create an acoustic black hole in a BEC. The team created a supersonic flow of atoms within the BEC, a flow that prevents any phonon caught in it from making headway. The region where the flow changes from subsonic to supersonic is an event horizon, because any phonon unlucky enough to stray into the supersonic region can never escape. The real prize is not the acoustic black hole itself but what it makes possible: the first observation of Hawking radiation. Quantum mechanics predicts that pairs of phonons with opposite momentum ought to be constantly springing in and out of existence in a BEC. Were one of the pair to stray across the event horizon into the supersonic region, it could never escape. However, the other would be free to go on its way. This stream of phononic radiation away from an acoustic black hole would be the first observation of Hawking radiation. The team hasn't gotten that far yet, but it can't be long now before either they or their numerous competitors make this leap."
I got a shot Bose amp here, and any sound you put in turns into silence. Voila, accustic black hole.
I'd sell this baby for cheap, too!
We used to have a Bill of Rights. Now, with the rights gone, all we have left is the bill.
that in space, no one can hear you scre...
If "disco" means "I learn" in Latin, does "discothèque" mean "I learn technology"?
"In one ear and out the other."
That's somewhere in between a metaphor for Hawking Radiation and the real thing. It's not true HR, but it would be a nice demonstration if they were to get it to work, especially if they could show some sort of analog to black hole "evaporation," which is the main implication of HR. I suppose that should naturally happen as the separation of the pairs sucks energy from the BEC and slows the fluid inside, shrinking the event-horizon-analogue.
Also, let's get properly flowing BEC layers in our noise canceling headphones!
"I zero-index my hamsters" - Willtor (147206)
Let's use the cone of silence, chief!
I knew light was quantized, but I had seriously never heard of Phonons, or that sound can be quantized as well.
Well, apparently it can: Phonon
There is an analogy there in the macro physics but that doesn't mean the small scale stuff like QM will be mirrored.
You can model gravity in the orbital mechanics sense with a marble and vertical cone that tapers at 1/square(height). That doesn't mean it will do anything relativistic or quantum mechanical.
Black holes in a Bathtub by E. Berti (2005):
www.iop.org/EJ/article/1742-6596/8/1/013/jpconf5_8_013.pdf
The argument basically goes that when you unplug your bathtub, there's a certain point at which waves generated past the "event horizon" near the hole never escape the hole. It's an interesting read, but I was under the impression that this is basically the same thing, albeit not an effect that arises from quantum field theory.
You'll create a BLACK HOLE that ENGULFS THE EARTH! Just like the LHC!
now we know how they made the "cone of silence" http://en.wikipedia.org/wiki/Cone_of_Silence
"Nigel Tufnel: The numbers all go to eleven. Look, right across the board, eleven, eleven, eleven and...
Marty DiBergi: Oh, I see. And most amps go up to ten?
Nigel Tufnel: Exactly.
Marty DiBergi: Does that mean it's louder? Is it any louder?
Nigel Tufnel: Well, it's one louder, isn't it? It's not ten. You see, most blokes, you know, will be playing at ten. You're on ten here, all the way up, all the way up, all the way up, you're on ten on your guitar. Where can you go from there? Where?
Marty DiBergi: I don't know.
Nigel Tufnel: Nowhere. Exactly. What we do is, if we need that extra push over the cliff, you know what we do?
Marty DiBergi: Put it up to eleven.
Nigel Tufnel: Eleven. Exactly. One louder.
Marty DiBergi: Why don't you just make ten louder and make ten be the top number and make that a little louder?
Nigel Tufnel: [pause] These go to eleven."
"Nigel Tufnel: It's like, how much more black could this be? and the answer is none. None more black. "
Sweet, now I just have to trick my wife into standing in it.. ah peace
Here, I'll fix it.
The real prize is not the acoustic black hole itself but what it might makes possible: the first observation of something analogous to Hawking radiation. The Theory of Quantum mechanics predicts that pairs of phonons with opposite momentum ought to be constantly springing in and out of existence in a BEC. Theoretically, were one of the pair to stray across the event horizon into the supersonic region, it could never escape. However, the other would be free to go on its way. This stream of phononic radiation away from an acoustic black hole would be the first observation of anything even vaguely resembling Hawking radiation. The team hasn't actually achieved any of this though. It can't be long now before they or their numerous competitors make this leap. Unless their hypothesis is totally wrong, which is entirely possible. But that doesn't sound particularly impressive, so we'll just forget about that bit...
-1 Uncomfortable Truth
The first Acoustic Black Hole was actually created back in 1981.
It must have been something you assimilated. . . .