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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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There's more information about the Pierre Auger Project here.
Nobody's talking about creating any more black holes than get created naturally. They are talking about detecting black holes that do get created naturally in our upper atmosphere.
If you actually need more explanation, go to the article.
OK,
- B
http://www.bradheintz.com/
- updated
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.
People, in general, disappoint me. Politicians even more so.
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.)
Gentlemen, you can't fight in here, this is the War Room!
Of course there are extra, invisible dimensions! Where else do you think all those socks go when you wash them in the laundry?
Sapere aude!
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
If we're going to go to such extreme wierdness as space having dozens of dimensions, why not just give up on the concept of position as fundamental quality of a particle? Between relativity and quantum mechanics, we've already lost absolute motion, flat space, and simultaneous exact position and momentum. What still makes so much sense about the concept of space?
Why not go for a dimensionless graph universe of immutable particles/nodes representing conserved quantities? In addition to mass particles, have energy particles, charge particles, etc. (these are bad examples, of course; given the mass-energy equivalence, a "particle" of kinetic energy would have to be a compound entity). Just set up the rules to define the various types of connections, which have variable quantities (or possibly, are made and broken; however it works out to be simpler) and for determining the probabilities with which they may change from one arrangement to another. To put it in programming terms, take the data out of the particles, and put it into the relationships between them.
It wouldn't be easy, it might be useless, but I know it would at least give me fewer headaches to start with a clean slate than to twist the classical ideas of space all out of shape.
You can certainly have a graph system that behaves identically to a spacial system (though a graph system of Newton's physics would certainly be uglier than his elegant concepts), and it would lead to fighting fewer spacial preconceptions that give people such a miserable time keeping up with modern physics.
Anyway, just a random thought.
I don't think Argentina is really the best location for a scientific observatory -- they're currently in the process of overthrowing their government. There is rioting in the streets, mass looting, etc, etc. If I was in charge I would want it to be in a country that was much more stable.
It has been suggested more than once in the litterature that cosmic rays might actually be linked with the mass repartitionin the universe. Superclusters are aranged in a sponge like maner. Astronomers have and still do wonder how this came to be, since it means either the universe was asymetric in the beginning or somehow became asymetric. Quantum non-locality gives a pretty satisfying answer : As a particle passes in "empty" space, it accelerates. how? well empty space isn't exactly empty, rather it's a swarming soup of particle anti-particle pairs being created and destroyed. The theory goes to say that the particle, over a long period of time, gets accelerated by the absorbtion of these half-photons being created and destroyed. The particles accelerate until they are slowed down by a gravitational field and thus matter conglomerates and empty space gets emptier. Those particles arrive at extremely high speeds and are thought to be the cause for cosmic rays.
Imperium et libertas
Autocracy and freedom
".....Argentine officals hope to discover new black holes, dimensions and other phenomena, and find new ways to send their debt there."
It's not that the energy would be from particles from higher dimensions, but rather that without the extra dimensions the cosmic rays would have insufficent energy to form the black holes in the first place. This is made pretty clear by even a cursory reading of the article, but that seems to doesn't seem to be the norm around here.
Now, a slightly more interesting question is why the extra dimensions would lower the threshold of singularity formation. Do they make space more compressible by giving it more room to flex in or what?
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)
-- look, cheese ahoy!
Yes. The process by which blackholes evaporate is called Hawking Radiation. One interpretation of the evaporation is that particles tunnel out of the gravity well by a quantum process exactly analogous to that attributed to spontaneous radioactive decay. Of course gravity isn't limited to a short distance, which decreases the probability of quantum tunnelling.
An alternative interpretation (and the more popular one), is that virtual particles of positive and negative mass enegries are created near the event horizon, and the negative mass energy particles fall into the black hole, while the positive mass particles escape. Ordinarily such virtual particles are created all the time and quickly annhilate each other back out of existence, but in the rare case that one crosses the event horizon they can't come back together and thus one becomes a real particle. Since we assume that negative mass energies can never be truly realized, only positive particles will ever escape.
In both cases the blackhole loses mass and appears to emit particles. In fact, there is nothing about Hawking radiation that makes either interpretation more valid than the other.
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...
The media and the rest of the world is convinced that Argentina is synonomous with Buenos Aires. That, and they're perfectly happy to sensationalize everything as well.
The observatory is actually in a place along the Chilean border called Malargue (you'll never find it on a map - ever) which (according to all my friends there) is a little bit worried about the goings on in BA, but life, for the most part, seems normal.
Seriously, the government overhaul is the least of the Observatory's problems - the biggest problems we have are getting things in and out of the country. International customs is horrible. Ever try to explain to someone what a photomultiplier is? Or how something that looks like a very big light bulb is worth $1000?
>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.)
Sorry for being so pedantic, but they also affect its charge and angular momentum. So you're essentially right, except that if you know, for instance, that either an electron or positron fell into a black hole, and you could somehow monitor its charge, you could distinguish which.
Matt Reece
How hawking radiation actaully occurs is something I understand but do not grok. I can't really explain from ground up, since I'm not an expert. I'll give it a try but don't quote me on this.
The whole process is lending a bit of energy from nothing, such that it won't violate conservation of energy by being strictly in limits of uncertanity part of uncertainity principle. Sometimes this energy is borrowed in form of two photons with opposite momentum, some times a particle-antiparticle pair. You have to pay back soon what you have borrowed, but sometimes the blackhole gets greedy and swallows either one of your photons or you particles. When the death calles for destruction, black hole no option but to pay back what debt it has inherited. So far, so good. Now here is the part I don't really understand (I can explain preceeding part in techincal terms and in detail if you prefer, but not this part) but accept: black hole for some reason pays the debt for the pair, not only the one it has assimilated. If it does this, the other particle, photon, whatever is free to roam the universe.
Gentlemen, you can't fight in here, this is the War Room!
The essential reason is that the "fundamental Planck scale" is ~ 1 TeV in LED (large extra dimension) theories. Gravity is a "bulk" field (propagates in all dimensions) while the standard model fields are localized, so this affects them differently. The gist of it is, if you put enough energy in a small enough region, you make a black hole. If there are more dimensions, the size of that region is bigger, so it's not as difficult to make black holes.
.8 TeV for D = 6 - 10.
Let me try to outline what's going on: I'm getting this from "Black hole production in TeV-scale gravity, and the future of high energy physics" by Steven Giddings (hep-ph/0110127 on arxiv.org). It's a nice article to start with, if you want to dig into the literature on this.
(By the way, this is using the "warped" extra dimension model but the general ones are similar.)
The Planck mass in D dimensions is M_p^(D-2) = (2 pi)^(D-4) / (4pi G_D) with G_D the gravitation constant. It turns out (M_4 / M_p)^2 = (M_p)^(D-4)V_{w}, with V_{w} the "warped volume" of the extra dimensions. (I'm not being very rigorous here; in fact this is how the volume is defined, and the ratio is given by a certain integral in terms of the warped metric.) This is essentially a sort of "Gauss law" argument, over the extra dimensions.
Now, let's consider a black hole with radius r_h much less than the geometrical scale R_c of the extra dimensions. It turns out that for a black hole of mass M, spin J, in the J = 0 limit, we have r_h = 2 [C M / M_p^(D-2) ]^[1 / (D-3)] where C is some constant in terms of D that I don't want to bother writing. The Hawking temperature looks like T_h = (D-3)/(4pi r_h). This description is valid roughly for M_p > 1.1 TeV -
Black hole cross-section was assumed to be geometrical (pi (r_h)^2), but as I mentioned in another post this is questioned (look up papers by Voloshin - but Giddings questions those), and there may be an exponential suppression. Anyhow, the important point is that, once you take all this into account, you get that the cross section sigma grows when D is larger, i.e. you don't have to put energy into as small a region if there are more dimensions.
Matt Reece
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.
>1 - If a charged particle drops into a black hole
>it has to change black hole's chargebecause of
>conservation.
This is correct - charge, momentum, and angular momentum are all globally conserved, so far as we can tell.
Note that "mass" is not *really* conserved - this is especially obvious in certain decays of elementary particles (i.e., electron+positron -> photon+photon; you end up with 0 mass). What *is* conserved is the energy-momentum four-vector (E, p), and for any one particle E^2 - p^2 = m^2. Mass only is conserved in the nonrelativistic limit. But I digress...
>2 - It also happens to be the case that no
>information can be obtained from (if you excuse
>the term) "inside of" event horizon,
This is basically true: no information is obtained. It is said that "black holes have no hair." But they do have a few properties - charge, mass, and angular momentum are essentially it. (Temperature and entropy also, but these depend on mass.)
>determine mass changes and angular momentum
>changes because it changes the shape and size of
>event horizon.
This is somewhat true; I'm not sure I would have expressed it in terms of "shape and size." I have to admit my knowledge of the black hole solutions in general relativity is fairly rudimentary, so I'm not sure in exactly what way that is true, but I think it is. There is a metric - called the "Kerr black hole" - that describes black hole solutions that spin; I think when they have charge there is another term. But the thing to note is that the metric of spacetime is actually different for different values of black hole spin, or charge. You'll also see a change in the electromagnetic potential (phi, A) outside the black hole for the charged case. So there are external effects.
>So how can charge be preserved if it doesn't
>affect event horizons properties? How can you
>tell total charge of a black hole?
The simple answer is: Maxwell's equations. Anything with charge, even a black hole, will change your electromagnetic potentials.
In other words, black holes tend to wear their charge, angular momentum, and mass "on the outside", in some sense.
Matt Reece
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.
This may sound like a silly question, but would it be theoretically possible for one of these potentially-existant curled up dimensions to uncurl?
What the universe be like if we suddenly got some osrt of extra spacial dimension?
Or going the other way, would there ever be any risk of one of our current spatial dimensions curling up?
Take a note of help from Ken Perlin. And the recent post about Tron should make him happy.
:)
Quick background info on him. He has worked on texture mapping for quite some time now. Created such things as "Perlin Noise." Here is a good example. He also got an oscar for this work.
I hope this all helps you visualize the hypercube now.
"Time is long and life is short, so begin to live while you still can." -EV
Electric field comes out of the event horizon. Actually it's more correct to say that electric field is created at the event horizon, since it doesn't make any sense to say that it propogates up out of the horizon. It is perfectly valid to say that the electric field lines have been frozen into the event horizon, and are a property of the event horizon. As charged particles cross the horizon they contribute new electric field which is measurable by the way it distorts and adds to the existing field lines.
Net charge is a property we could infer from the electric field, but the actual field emanates from the event horizon, not the unreachable singularity.
Wow!
+ Wierd for sure
Jaysyn
There is a war going on for your mind.
Very soon I will be able to travel between these alternate universes, and assassinate all my alternate selves. By doing this, I shall transfer all their energy to my own body. I will be the posessor of godlike speed, strength, and intelligence! It's not murder, I'm just collecting all the excess energy into one container.
I shall be The One!
-3Suns
~~~~
The Revolution will be Slashdotted
Not likely - there's really no commercial value in any of the parts. That, and the "facility" is actually 1600 square kilometers of desert/ranch: if the locals stormed it, they'd get attacked by an angry bull (trust me: it's not pleasant to stare at a bull defending a herd).
Please also realize that Argentina (media) = Buenos Aires, and Argentina (country) = a whole lot more. Malargue, the place where the observatory is located, is about as "politically unstable" as we are - not that that's saying a whole lot. Really don't trust the media as to what's going on in Argentina.
Also, who exactly would buy a PMT on the black market? They're useless commercially. The only thing of any value commercially in the entire project are the solar panels for power, and they'd be rather difficult to take (and not be noticed by the gauchos - a covert op into a ranch is not exactly easy).
Finally: SuperK is not downed at all. If you check their Web site, it's an absolute given that they're going to rebuild the observatory. $30M for one experiment that's proven and contributed massively to science is dirt friggin' cheap.
As soon as they find the black holes in our atmosphere, I can reclaim my lost pens, socks and lighters -- maybe even bring back Jimmy Hoffa.
The most energetic cosmic rays are 10^14 more
energetic than the largest human accelerators.
The tradeoff is "luminosity". You may only see a
few of the highest energy cosmic rays in a year,
while you want zillions of hgih energy particles
in an accelerator.
You'd think so, wouldn't you? But it isn't hard to calculate the tidal stresses on particles with world-lines passing through the throat region (it's just differential acceleration, after all). I know nothing can pass through a Schwarzschild throat, but that's not true of a Kerr metric. Of course, that's assuming that the throat opens up in another location of the universe and that it's not behind a horizon there, but hey.
That link's broken. Can you repeat the question or email me directly?
Well, from what I know about black holes, as matter passes through the event horizon, the entropy increases. This increase in the black holes entropy translates into an increase in the size of the event horizon. So, as the mass increases, so does the event horizon. At the same time, the temperature of a black hole is inversly proportional to the mass. So the temperature decreases as the mass increases. On the flip side, if the mass is small, the event horizon is small, and the temperature is extremely high. Since we are talking about a extremely small black hole, we are talking about photons being radiated at an extremely high energy in a very short time. Now I understand that the uncertainty principle allows extreme fluctuations in changes in energy as long as it is "paid back" within a short amount of time. But it seems that this extreme "Heat" is being radiated off by extremely energetic photons. In my layman analysis, it would seem that such extreme energies in our atmosphere would be detectable by several means. In lieu of this, I can understand that if there are 10 spatial dimensions, energy is being radiated in all dimensions and therefore in the three spatial dimensions we experience, we would only see a fraction of the total energy radiatated. Now for my question. It would seem likely that the radiation radiates in proportion to the spacial dimensions. If these extra spacial dimensions are soooo small, then they would have only a small fraction of the total energy radiated. Therfore, wouldn't we STILL see a phenomenal amount of energy in our atmosphere from the Black Hole Evaporation???? (Sorry for the length).
Life is like a box of chocolates. I hate Chocolates!
T
---- It puts the lotion on its skin or else it gets the hose again. It does this whenever it's told.