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Black Holes and Hidden Dimensions
Slackware Geek writes "It is being reported in the Nature Science Update that a new observitory being built in Argentina to study cosmic rays could detect extra hidden dimensions if they exist. 'Cosmic rays could find holes in Standard Model of particle physics ...If the Universe contains invisible, extra dimensions, then cosmic rays that hit the atmosphere will produce tiny black holes. These black holes should be numerous enough for the observatory to detect.'"
Does anyone know how this works? Is this detecting the Hawking radiation from an evaporating hole, or is it detecting other effects?
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I wonder if this can shed some light on the subject. It talks about modeling a universe where light naturally travels at a fixed radius rather than a straight line. Assuming the radius to be extremely large, the proposed universe would act quite similarly to ours. Assuming an extremely small radius (small as in atomic-level) and I think we may be hitting upon the door of the next dimensions.
Think of it... In a world where light traveled in a fixed radius of one meter, you would see the back of your head if nothing is in the way. And, it would seem, that your head is 6.28 meters away from you. Problem is, you wouldn't be able to see beyond that one-meter radius circle. Now, what if that radius was shrunk to the atomic level... you wouldn't be able to see beyond the circle(sphere?) that the fixed radius spans. Obviously, your eye is way too large to detect that kind of precision.
Thoughts anyone?
IWARS.
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Reply to parent: nothing. antimatter is not a very exotic thing, normal matter with reverse charge reverse spin. Once in the blackhole there is no telling whether what fell was matter or antimatter, they all behave the same (increase black hole's mass, that is, and nothing else.)
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This would be a nice feather in the cap of string theory, which to this point does not have any experimental observations to back it up.
One of the predictions (or you could say requirements) of string theory, is that the universe contains a total of 11 space-time dimensions, 7 of which are "curled-up" and are extremely tiny. Every time you move, you pass through the entire universe in each of these 7 dimensions, although your position in the 3 "enlarged" dimensions hardly changes. The interesting thing is that a guy predicted these extra dimensions way back in the 1910's, and was ignored for about 50 years. Experimental evidence on the side of string theory (or as they're calling it now, M-theory) would go a long way towards convincing the experimental physicists that all these theoretical physicists aren't off their rockers.
---- El diablo esta en mis pantalones! Mire, mire!
As the article said higher up, the smashing of cosmic rays into ozone has been known to create such an amount of energy at such a tiny level that an extremely unstable black hole can be created for an infinitesimal period of time. This object does not have close to enough energy to suck anything into it. Even if the black hole created was a bit larger than an atom, it couldn't do more than take in a few atoms before it expends the energy it has available and "fizzle[s] out".
The article also states that it is a decently rare experience that rays with enough pent-up energy arrive that a black hole can be created.
The attempt to generate these black holes ourselves is somewhat of a different matter, but not much. CERN originally got a lot of flak for attempting to do this, since a lot of uneducated people freaked out about the thought of a black hole being created. But, that has since died down because it was so long ago and, annoyingly, the average person is kinda forgetful :).
Now, onto the good stuff. The black holes that CERN is attempting to generate are the equivalent of those that the article talks about that the PAO is trying to detect. Why it won't hurt us is due to the nature of black holes and how they are created.
A black hole requires an immense amount of energy to be created on a grand scale. That's the reason that only the largest of giant stars will become black holes when nova. The more energy it has in it while in a black hole state, the greater stability is has (though it's likely excruciatingly chaotic, and that's another branch of really fun science :). The ones that will be created will only have a small amount of energy, so little in fact that they could not possibly stay in existence for long enough to do damage. More so, with every particle that is brought into the black hole it requires a specific amount of energy expended by the black hole to drag this particle in. This is, of course, the fun part because no one's quite sure what happens to this particle. Does it disappear from our dimension? Does it come back when the black hole dissipates? There's only one way to find out, and by using harmless black holes so small they cannot do any sort of damage (if it's really damage) to more than a few nearby atoms, we are extremely safe from the attempt.
Hope you find some solace in all that :)
- DaftShadow
Cosmetic rays will indeed prove that the univers is shallow and one dimensional.
forma3
".....Argentine officals hope to discover new black holes, dimensions and other phenomena, and find new ways to send their debt there."
The problem is that
"The result of casting elementary particles outside the inheritence hierarchy is undefined."
The Manual 4.1, chapter 7 cited in Universe(3)
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And every particle DOES have "simultaneous exact position and momentum," it's just that we aren't capable of determining both through observation. We can determine one or the other.
No, not exactly, though this is a common misconception.
Heisenberg's Uncertainty Principle has nothing to do with the act of observation. The actual uncertainty is fundamental to the quantum model. It's not that you can't measure both the position and the momentum at the same time, it's more that the particle's wave aspect cannot be constrained by both 'measurements' at the same time. Think of the particle like a water balloon on the position/momentum graph: if you compress it in one direction (measuring position) it spills out in the other (uncertain momentum).
The fun part is that you can actually use the uncertainty principle to make more accurate measurements. An experiment that was done years ago in Australia proved this. The idea is that a photon travelling here from a distant star has a very narrowly defined transverse momentum: it's heading almost directly towards us, so the uncertainty in its side-to-side momentum is directly related to how much space it takes up in the sky. (Since that defines the range of angles the photon could arrive from.) Since the transverse momentum is highly constrained, the transverse position must be highly spread out. So in theory the photon could be seen as a paper-thin pancake several miles across.
Now, from the standard double-slit experiments, you get an interference pattern as long as there is a possibility of the photon 'hitting' both slits at the same time. In this experiment, the slits were replaced with radio telescopes on train cars, on a long straight section of track. (Hence why this was done in the Australian outback.) So long as the telescopes are closer together than the uncertainty in the photon's position, you get an interference pattern. Once they're further apart than that, you revert to two seperate streams of photons.
So, you slowly move the telescopes apart, watching the star, until the interference pattern disappears. Presto, you have the 'size' of the photon, which gives the uncertainty of its transverse position. Back-calculating throug Heisenberg's inequality gives you a limit on its transverse momentum. And that gives you a good idea of the 'size' of the star in the sky, in fractions of an arc second.
This has been done, and gave answers that agreed with other observations of the stars. So the Uncertaintly Principle has, in this case, improved the accuracy of measurements.
And demonstrated that the HUP is a lot more fundamental than what you said. Particles simply do NOT have "simultaneous exact position and momentum."
-- Bryan Feir
Oh my God, I'm amazed - this is the observatory I actually WORK for, and it's on SLASHDOT, my God.
Forgive me for going completely crazy replying to everyone, but this is just too cool.
OK, so long as people promise not to Slashdot the server (heh, that was dumb) for anyone who wants more information, go to the main Auger website, or for even cooler information, go to the Auger site in Argentina.
Auger is actually a very interesting project, and it's not like anything you'd ever think of - it's a 1600 km^2 array of water Cerenkov detectors (10 cubic meters of water) spaced 1.5 km apart - the picture in the article is of the flourescence detector, which is more like what you think of for a standard detector, but due to the limitations of the flourescence method of detecting cosmic rays, its duty time is only 10%, as opposed to the 100% of the surface array.
The project is proceeding along... pretty well. We've basically finished the Engineering Array, a small-scale testbed to find all of the design flaws in the initial project (and boy, did we find them) and we've detected some cosmic rays which we believe to be ~10^19 eV. We've also demonstrated the hybrid design as well (events where the flourescence detector triggers as well as the surface detector).
The black hole stuff isn't the important goal of the project - the goal is to elucidate the spectrum of cosmic rays above 10^20 eV, because we have no idea where those particles come from - all of basic physics says they can't exist. This is one of the big questions in astrophysics in recent years, up there with gamma ray bursts and odd quantum states of matter.
It's way cool. And not just because I work on it...
Unfortunately, this argument isn't very likely. The main problem we have is how to accelerate particles to such high energies - 10^20 and above is impossible by any stretch of the imagination, but the 3 x 10^20 particle that slammed into Dugway, Utah appeared to have a slightly better imagination than humans.
Empty-space acceleration would have to be massive to counteract the utterly huge deceleration caused by energy loss in galactic/extragalactic magnetic fields, interaction with the interstellar medium, and, most importantly for extreme high energy cosmic rays (UHECRs), the GZK effect - photopion production by interaction with the cosmic microwave background radiation. It's simply not possible to accelerate particles like this in empty space - we would've seen it already in particle accelerators.
Seriously, physicists right now have no idea how these particles are accelerated. Supernovae? Not nearly enough energy, by any stretch of the imagination - fundamental arguments like conservation of energy kill you far below the 10^20 eV limit. Gamma-ray bursts? Maybe, but the distribution of cosmic-rays doesn't agree with GRBs as a possible source. Extragalactic? Not unless you throw away basic physics and ignore the GZK effect - there's no way they could propagate that far.
Basically, the one question that there have been tons upon tons of papers in the recent literature for is "where is this gigantic particle accelerator nearby us?"
You're right - they don't jive.
:) A black hole is completely described by its charge, mass, and angular momentum. It has no other properties (hence "black holes have no hair" - "hair" in this case is any other property).
So, to explain: black holes have three properties. They're the universe's most massive particles in that respect.
Charge does affect the event horizon's properties, basically in the same way that angular momentum does - it alters it massively. You can get very weird black holes, including ring singularities instead of point singularities (black hole donuts!).
In reality, it's very difficult to charge up a black hole. Most of the matter falling in is neutral, and a buildup of one charge will result in a preferential draw of the other charge (opposites attract, y'know) and therefore, an overall neutral black hole. In falls an electron, and a proton is drawn preferentially over another electron. You also need a ton of charge to change the event horizon significantly - but in theory, it is possible to tell.
It's mainly shape of the horizon and shape of the singularity that's affected due to charge/angular momentum. That, and the stability relation - too much charge/angular momentum, and everything goes to hell in a handbasket. If I had my copy of Misner, Thorn, and Wheeler here, I could expound a bit, but...
Schwarzschild metric: mass only
Kerr metric: mass+angular momentum
Reissner-Nordstrom metric: mass+charge
Kerr-Newman(sp? on second): mass+charge+angular momentum - i.e., real black holes.
J messes with the angular dependence and structure of the horizon. Not sure what charge does - it doesn't enter into the metric in many places other than the numerator. You'll note that a != 0 causes the metric to be nonsingular at the origin...
Charged/spinning black holes are interesting, because the Schwarzschild throat/Einstein-Rosen bridge may be passable in some geometries. For a standard Schwarzschild geometry, it's not - try to pass through the center of a nonspinning noncharged black hole, and you'll die, as it's not stable.