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Black Holes and Hidden Dimensions

Posted by Hemos on from the looking-into-my-other-universe dept.

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.'"

13 of 200 comments (clear)

  1. Miniature Black Hole by alfredw · · Score: 4, Interesting

    Does anyone know how this works? Is this detecting the Hawking radiation from an evaporating hole, or is it detecting other effects?

    --
    In Soviet Russia, sig types you!
  2. `Width' of a single atom by joebp · · Score: 2, Interesting
    Many physicists now argue we cannot experience these extra dimensions directly because they became rolled up more tightly than the width of a single atom during the Big Bang.
    Wow, how scientific.

    There's more information about the Pierre Auger Project here.

  3. "Extra" by Anonymous Coward · · Score: 1, Interesting

    Extra is the wrong word; "undetected" or "hitherto unseen" is more accurate. Extra implies "laws of nature" and similar nonsense that the cult of science preaches to the guild.

    Any other dimensions that are there are already existing, and are not "extra" or in addition to whats in the universe.

  4. Random thought: no dimensions, no space by Nindalf · · Score: 3, Interesting

    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.

    1. Re:Random thought: no dimensions, no space by Bryan+K.+Feir · · Score: 5, Interesting

      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

  5. Argentina -- a bad idea. by juju2112 · · Score: 3, Interesting

    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.

  6. Re:Experimental proof for string theory by wpmegee · · Score: 2, Interesting
    Or, we could just build a superconducting particle accelerator as large as the solar system. Then we could probe distances as small as the Planck length (the approximate size of most strings).

    Then again, with the SSC canceled, maybe not . . .

  7. More info on the Observatory by barawn · · Score: 5, Interesting

    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...

  8. Re:Experimental proof for string theory by mreece · · Score: 3, Interesting

    Detection of signatures of large extra dimensions wouldn't actually offer direct experimental evidence for string theory. Yes, string theory predicts extra dimensions, but it isn't necessarily the only theory that does.

    Direct evidence for string theory at any point in the near future is highly doubtful. We just can't get good evidence of such high energy scales. We could see associated effects, like extra dimensions or supersymmetry, but those don't necessarily imply string theory.

    --
    Matt Reece
  9. Re:Possible source of cosmic rays by barawn · · Score: 4, Interesting

    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?"

  10. Re:antimatter particles by barawn · · Score: 4, Interesting

    You're right - they don't jive.

    So, to explain: black holes have three properties. They're the universe's most massive particles in that respect. :) 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).

    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.

  11. What if one uncurls? by LichP · · Score: 2, Interesting

    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?

  12. UFOs are actually WormHoles by Anonymous Coward · · Score: 1, Interesting

    UFOs are actually WormHoles