Artificial Black hole?

[Reaper]

What do you make of this article, by physicsworld? http://physicsworld.com/cws/article/...DF0BFCC2F917EC

 

It would appear as if they made an artifical black hole in the lab.... Not a gravitational one, but they say that you could make one in an optical fiber, though the method shown is a bit questionable, to say the least.

[tmaromine]

The link seems to be down.

 

This post reminded of an article I read of CERN, how that they connected to or created another universe for a few seconds with their particle accelerator and basically mused about who deserves to be god of it – they've kept it low so that religions don't go crazy. It was on a gay news site for whatever reason, but I haven't been able to find it.

 

Finally has come the day when humans make black holes and universes !

[CraigD]

The physicsworld article “Artificial black hole created in lab” describes experiments by Ulf Leonhardt similar to the many “making light slow/hold still” experiments of the past decade or two. All involve using materials with high refractive indexes, like special glass fibers, or cold gasses. The “reduced local speed of light” isn’t really a change in the speed of light in vacuum, but in an ensemble of photons apparent speed as it interacts with the refracting matter in carefully made experimental optical materials.

 

The idea, I gather from the article, is that the vacuum pair production events that are thought to produce Hawkin radiationfrom a black hole, where virtual particle/antiparticle pairs that usually annihilate back into vacuum are separated by a black hole’s strong gravity gradient, can be produced by having a strong refractive index gradient.

 

This makes some intuitive sense. If a virtual particle from a vacuum energy pair production event can get snagged by a black hole, why not get snagged by some matter in a refractive medium? There’s already pretty convincing evidence, by way of the Casimir effect, that a very tiny gap between metal plates can snag them, producing a physical force (which, in the quantum physical terms appropriate to talking about this sort of thing, is a sort of EM radiation) so all that’s really different in Leonhard’s experiment is the photons to be produced.

 

:D The catchy “Artificial black hole” headline, and the implications of godlike universe creating, are, I think, pretty much just showmanship. Nothing in these devices are causally disconnected from the main universe the way a black hole is thought to be, so calling them “Artificial black holes” because they can get real particles from the virtual-particle soup of vacuum is like calling a Casimir effect experiment an artificial black hole because it emits something similar to Hawking radiation, or calling a flashlight an artificial star because, like a star, it emits light.

 

;) Hype aside, it’s an impressive work of experimental physics, and, if good results can be gotten from it, further confirmation of theoretical predictions.

 

Magazine articles and physicists are both interested in getting attention, so their hyperbole is understandable – but we do well not to get carried away by over-literal interpretations of it. :)

[freeztar]

It's an interesting experiment, but I agree with some of the comments, it is hyped up. This experiment does not create an actual black hole, but mimics one with fibre-optics and refraction. They also simulated white holes.

 

This post reminded of an article I read of CERN, how that they connected to or created another universe for a few seconds with their particle accelerator and basically mused about who deserves to be god of it – they've kept it low so that religions don't go crazy. It was on a gay news site for whatever reason, but I haven't been able to find it.

 

Finally has come the day when humans make black holes and universes !

 

I have never heard of anything of the sort coming out of CERN. I suspect the reason that you can not find the research is because it doesn't exist. I'd be extremely surprised if such an enormous advancement in physics was kept hush-hush for fear of stepping on the toes of religion.

 

Plus, even if we could create a universe, it would still be in this one, in which case it would be part of this universe and not *another*.

[freeztar]

The idea, I gather from the article, is that the vacuum pair production events that are thought to produce Hawkin radiationfrom a black hole, where virtual particle/antiparticle pairs that usually annihilate back into vacuum are separated by a black hole’s strong gravity gradient, can be produced by having a strong refractive index gradient.

 

This makes some intuitive sense. If a virtual particle from a vacuum energy pair production event can get snagged by a black hole, why not get snagged by some matter in a refractive medium? There’s already pretty convincing evidence, by way of the Casimir effect, that a very tiny gap between metal plates can snag them, producing a physical force (which, in the quantum physical terms appropriate to talking about this sort of thing, is a sort of EM radiation) so all that’s really different in Leonhard’s experiment is the photons to be produced.

 

What about the last paragraph:

However, Renaud Parentani of University Paris-Sud in France thinks that, although it may be possible to glimpse radiation from an event horizon in future versions of the group’s system, the radiation might not possess all the expected properties of Hawking radiation generated by astrophysical black holes. For instance, the fibre-optic system is limited by dispersion, which means that the wavelength of photons produced at the event horizon will not be stretched very far.

 

Would they have to factor this into their experiments to gain insights into Hawking radiation? I'm confused about the significance of the "initial" wavelength. ;)

[tmaromine]

I have never heard of anything of the sort coming out of CERN. I suspect the reason that you can not find the research is because it doesn't exist. I'd be extremely surprised if such an enormous advancement in physics was kept hush-hush for fear of stepping on the toes of religion.

 

Plus, even if we could create a universe, it would still be in this one, in which case it would be part of this universe and not *another*.

 

That makes sense too... I'll see if I can refind it.

 

If there's multiple unuverses (like string theory requires ?), they could connect to it, no?

[InfiniteNow]

That makes sense too... I'll see if I can refind it.

 

If there's multiple unuverses (like string theory requires ?), they could connect to it, no?

 

I believe you are thinking of brane theory, or "M-theory," a sort of cousin or off-shoot of string theory where each "universe" is a sort of membrane, sort of like slices of bread all beside each other and each slice is a universe itself. IIRC, String theory requires multiple dimensions, not universes.

 

 

Is it just me, or does the term "universe" not make sense in the plural? :(

 

 

American Scientist Online - Hawking's Brane New World...

[CraigD]

If there's multiple unuverses (like string theory requires ?), they could connect to it, no?

Though my knowledge of the history of ideas around this and of string theory is such that there’s a good chance I’m at least slightly wrong, the idea of multiple universe as a concept in physics stems from the many-worlds interpretation of quantum mechanics, which appeared in the 1950s. There was a rich tradition of speculation by mainstream physicists about “hidden worlds” dating back at least a couple of centuries, but mostly as a sideline , little connected to rigorous science, and often ending in embarrassment (eg: stage magician Henry Slade’s fooling of future physics Nobel laureate Rayleigh) when scientists attempted to investigate it with greater rigor.

 

To the best of my knowledge, string theory no more requires the MWI than do other quantum mechanical theories. The MWI is an interpretation – a means of putting into intuitive perspective in order to “make sense of” the hard science of quantum physics – not itself a scientific theory. By definition, it accepts conventional quantum mechanical theory as correct, making no attempt at any experimentally verifiable prediction disagreeing with the theory it interprets.

 

In the MWI, the “many worlds”, or many universes, are by definition unable to effect one another in any way. The many worlds differ in that specific, unambiguous measurments have different, mutually exclusive outcomes in them (eg: “particle detector #123 registered 1 detection event between 00:00:15 and 00:00:16” vs. “particle detector #123 registered 0 detection events between 00:00:15 and 00:00:16”). A person in a universe cannot perceive other than that universe.

 

The idea that separate universe and black holes have something to do with one another comes from the prediction that no signal of any kind can cross the event horizon of a black hole, so the distinct, measurable volume within this roughly spheroid boundary are in every possible way disconnected from one another. This kind of separateness doesn’t require quantum mechanics to be true or accurate – the universe could be “classical all the way down”, and the theory of relativity still be true, black holes still be predicted by it, and the universes within and without their event horizons still be utterly disconnected.

 

Many quantum mechanical predictions actually invalidate the possibility of black holes producing disconnected universes. Hawking radiation, for example, provides a potential mechanism of sending a signal from within an event horizon to without – and in some variations, vice versa.

 

I believe you are thinking of brane theory, or "M-theory," a sort of cousin or off-shoot of string theory where each "universe" is a sort of membrane, sort of like slices of bread all beside each other and each slice is a universe itself. IIRC, String theory requires multiple dimensions, not universes.

I agreed about string theory - though I think that, having failed to make any testable predictions different from those of traditional quantum particle physics, string theory is misnamed, being more of an approach to writing an as yet unknown theory than an actual theory.

 

Brane theory (which I understand even less well than string theory) introduces a third kind of “other universe”, distinct from MWI “worlds” and GR black hole “separate universes”. Unlike string theory (which can be considered a special case of a 1 dimensional brane theory), brane theory actually makes some practically, though experimentally difficult, testable predictions, so is, IMHO, a family of true scientific theories.

Is it just me, or does the term "universe" not make sense in the plural?

That a pretty philosophical question, I think. :eek:

 

The separate universes of the simplest version of the MWI and General Relativity’s black holes are causally disconnected from each other – that is, there is no way any information about a universe – even its existence - can be obtained by another universe. I’m pretty comfortable with considering such universes to be both many, and non-existent, except, of course, for ours.

 

Brane theory (including string theory variations that are really brane theories), on the other hand, requires the possibility of causal connection between n-dimensional branes, in which are embedded “worlds” or universes, in a (n+1)-dimensional “world space”. So, I’d consider world space and its embedded branes and worlds to be a single universe.

[tmaromine]

When I learned of string theory on the science channel, brane theory was in the same show, so I must've been thinking them the same. Be the logical plural of universe multiverse ?

 

Well, I've found that link. Looking at more things on the site, it looks like it's a joke site, so there goes that.