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Test for String Theory Developed

Posted by samzenpus on Wed Feb 08, 2006 10:14 PM
from the new-dimensions dept.
Space Science
inexion writes "PhyOrg is reporting that SLAC (Stanford Linear Accelerator Center) scientists have found a way to test the revolutionary theory, which posits that there are 10 or 11 dimensions in our universe. This past December, Joanne Hewett, Thomas Rizzo, and student Ben Lillie published an article in Physical Review Letters which shows theoretically how to measure the number of dimensions that comprise the universe. By determining how many dimensions exist, Hewett and Rizzo hope to either confirm or repudiate string theory under specific conditions which would consist of creating and examining 'micro-black holes', which could be formed by smashing two high energy protons together. Using the predicted decay properties of the emitted neutrinos, Hewett and Rizzo solved equations to find that our universe may have more than 10 or 11 dimensions -- too many dimensions to be explained by string theory."

Related Stories

[+] Fundamental Constant Possibly Inconsistent 317 comments
dylanduck writes "Cosmologists have begun thinking that yet another fundamental constant of nature is, er, not constant. The constant in question is the ratio of a proton's mass to that of an electron. It governs the strong nuclear force but there's no explanation for why that ratio should be constant. If true it would provide support for string theory, which predicts extra spatial dimensions." From the article: "Researchers at the Free University in Amsterdam in the Netherlands and the European Southern Observatory in Chile discovered the variation in mu. They did it by comparing the spectrum of molecular hydrogen gas in the laboratory to what it was in quasars 12 billion light years away. The spectrum depends on the relative masses of protons and electrons in the molecule."
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  • A Lot of 'Theoreticals' (Score:5, Interesting)

    by eldavojohn (898314) * <my/.username@@@gmail.com> on Wednesday February 08 2006, @10:16PM (#14674708) Homepage Journal
    How many micro-black holes have we measured in a lab?

    None.

    How many micro-black holes have we even seen?

    None, as it turns out [wikipedia.org].

    This is a story of hope and speculation--much like the story of super string theory.

    Hell, do we even have the capabilities to smash two high energy protons together?

    To be fair, Bosonic Super string theory has room for 25 [wikipedia.org] dimensions but it's flawed with tachyon, the so called imaginary mass.

    I'd be interested to know how they intend to measure the micro-black holes.
    • >Hell, do we even have the capabilities to smash two high energy protons together?

      Yes, it's routine.

    • Re:A Lot of 'Theoreticals' (Score:5, Informative)

      by kebes (861706) on Wednesday February 08 2006, @10:25PM (#14674747) Journal
      Hell, do we even have the capabilities to smash two high energy protons together?

      Well particle accelerators have been smashing high-energy protons together for a long time... but can we smash them hard enough to create micro-black-holes? No. ... not yet, anyways. But that's why the Large Hadron Collider [web.cern.ch] is being built! This is the frontier of particle physics.

      I'd be interested to know how they intend to measure the micro-black holes.

      The LHC has been in the works for a long time, and should come online sometime in 2007. This instrument will be able to probe these questions, and set limits on the possibility of micro-black hole production, as well as extra dimensions.
      [ Parent ]
    • I'd be interested to know how they intend to measure the micro-black holes.

      I dunno... Is this kind of treading on the "igniting the atmosphere" kind of problem with A-bombs.

      I mean if make a mini-black hole and drop it on the floor by acident, wouldn't it j

      • My God! It's Ed Wood! (Score:5, Funny)

        by eldavojohn (898314) * <my/.username@@@gmail.com> on Wednesday February 08 2006, @10:38PM (#14674809) Homepage Journal
        I mean if make a mini-black hole and drop it on the floor by acident, wouldn't it just absorb more and more mass on the way to the center of the earth.
        I didn't know Ed Wood developed plot lines on Slashdot.
        [ Parent ]
      • Hawking radiation [wikipedia.org] is a very good thing.

      • The universe is safe. (Score:5, Informative)

        by kebes (861706) on Wednesday February 08 2006, @10:45PM (#14674843) Journal
        All black holes emit Hawking radiation [wikipedia.org], which is essentially black-body radiation [wikipedia.org] (the object is trying to come into thermal equilibrium with the rest of the universe, so is emitting/absorbing radiation to do so). The origin of Hawking radiation is vacuum pair production [wikipedia.org], if anyone is interested. This radiation causes the black-hole to slowly "evaporate." The temperature (hence rate of evaporation) is inversely proportional to the black-hole mass (hence size).

        Micro-black-holes are (obviously) very small. Thus, they evaporate very, very quickly. In fact, they are well below the sustainable threshold, and will evaporate much faster than they accumulate new mass. Also note that these micro-black-holes have quite low mass, hence their graviational attraction is pretty much nill. They are "black holes" because their mass density is infinite, and they are thus a singularity, but nothing about "black holes" definitely implies "consumes matter indefinitely" (this only happens for black holes of sufficient size).

        So, no, there is no danger with micro-black-holes eating up the entire Earth. Yes, our current theories may be incorrent (you never know), but if micro-black-holes were able to grow without bound, then you'd expect the universe to be littered with black holes all over the place (which is not the case). Thus there's no reason to worry: the LHC will not gobble up the Earth.
        [ Parent ]

        • Phew!! (Score:2)

          by Nikker (749551)
          So, no, there is no danger with micro-black-holes eating up the entire Earth

          Man I'm glad I read this as a /. post I was really worried there for a second....

        • Re:The universe is safe. (Score:3, Interesting)

          by blamanj (253811)
          Slightly off-topic question. Does vacuum pair production have anything to do with inflation? I've never understood what drives the rapid expansion right after the big bang.

          • Re:The universe is safe. (Score:3, Informative)

            by Dan Hayes (212400)
            No. Inflation is caused by the decay of a scalar field which goes from a higher energy state to a lower one... this releases vast amounts of energy which drives inflation. I think this field is the Higgs field, which gives particles their mass.

        • Re:The universe is safe. (Score:3, Informative)

          by Ruie (30480)
          In addition one should not forget that Earth atmosphere gets routinely bombarded by cosmic rays - some of which are very fast protons, much faster than what we can create in the best colliders.

          So if there was a way to create an indefinitely growing black

          • Re:The universe is safe. (Score:5, Interesting)

            by ArbitraryConstant (763964) on Thursday February 09 2006, @01:35AM (#14675481) Homepage
            "Of course, we also don't have Large Hadron Colliders all over the universe, smashing particles together with enormous speed and accuracy, do we?"

            The universe can easily put our best efforts to shame. For example, the Oh My God particle [fourmilab.ch]. If constant bombardment by these sorts of particles hasn't yet destroyed us, it's doubtful anything we do will make it worse.
            [ Parent ]

      • Re:A Lot of 'Theoreticals' (Score:3, Interesting)

        by Jerf (17166)
        What ultimately put my mind at ease with regard to all of these "what ifs" is the recognition that cosmic rays routinely smash into the Earth with energies that we can still only dream of; for instance, see the Oh-My-God particle [fourmilab.ch], an impact event still sev

  • The actual scientific paper... (Score:5, Informative)

    by kebes (861706) on Wednesday February 08 2006, @10:16PM (#14674709) Journal
    The reference for the actual scientific paper in question appears to be:
    "Black Holes in Many Dimensions at the CERN Large Hadron Collider: Testing Critical String Theory" JoAnne L. Hewett, Ben Lillie, and Thomas G. Rizzo Phys. Rev. Lett. 95, 261603 (2005) .

    For those with access to PRL, the doi for the paper is: 10.1103/PhysRevLett.95.261603 [doi.org]

    This is the abstract:
    We consider black hole production at the CERN Large Hadron Collider (LHC) in a generic scenario with many extra dimensions where the standard model fields are confined to a brane. With ~20 dimensions the hierarchy problem is shown to be naturally solved without the need for large compactification radii. We find that in such a scenario the properties of black holes can be used to determine the number of extra dimensions, n. In particular, we demonstrate that measurements of the decay distributions of such black holes at the LHC can determine if n is significantly larger than 6 or 7 with high confidence and thus can probe one of the critical properties of string theory compactifications.
    For those without access to PRL, you can view a different version of the manuscript on arXiv. [arxiv.org]

    My comments (with the usual disclaimer: while I am a scientist, I'm not a particle physicist/string theorist, so I would appreciate any corrections to what I say): This work appears significant. String theory is incredibly elegant and fits in very well with other (experimentally verified) theories (quantum field theory, etc.). However, what string theory has always lacked, is experimental backup. The fact that there may be a way to experimentally test one of its predictions/requirements (that of extra dimensions) is truly significant, and will allow these fundamental theories to be advanced way beyond their current speculative nature.

    As I understand it, one of the current "problems" in string theory is an over-abundance of theories. There are millions (perhaps even an infinite number) of theory-variants that are all consistent with the current string-theory formalism. Of course only one (or possibly zero) of the theories is right. An experimental test would (I hope!) help pick out which theory variant is the right one... or perhaps tell us that string theory is completely wrong! Either way it's a good thing for science and I look forward to this test being performed at the LHC.
    • There are millions (perhaps even an infinite number) of theory-variants...

      But is this infinite number countable -- or is it continuous? ;-) Big difference, you know...

      Paul B.
    • i believe that witten showed two classes of these theories to be equivalent. as i recall, it's an open question as to whether all classes are equivalent. kind of the physicist's version of the P?=NP problem as i recall (i am most certainly not a physicist,

    • Re:The actual scientific paper... (Score:5, Interesting)

      by davidoff404 (764733) on Wednesday February 08 2006, @11:37PM (#14675038)
      String theory is many, many things, but elegant it is not. Furthermore, it doesn't fit in well with other theories simply because we can't get a prediction out of the damn thing.

      This paper is fluff. I read it when it first came out last March and I disagree strongly with the 5 sigma estimate in the test case they describe.

      And yes, IAAStringTheorist.
      [ Parent ]

      • Re:The actual scientific paper... (Score:4, Informative)

        by joahewett (953232) on Thursday February 09 2006, @03:19PM (#14680931)
        Hello - this is my work. The results of the paper have been blown out of proportion all over the web, and I am quite upset about that. However, the results are honest and credible within the model they pertain to. Our statistical calculation is not an "estimate" as you claim, but is the result of a sophisticated Monte Carlo simulation of the process as it appears in the detector at the LHC. Like it or not, this is a 5 sigma measurement at the LHC.
        [ Parent ]

    • Re:The actual scientific paper... (Score:5, Interesting)

      by bcrowell (177657) on Wednesday February 08 2006, @11:45PM (#14675083) Homepage
      From a brief perusal of the paper, it looks to me like:
      1. It's talking about highly hypothetical experiments that they imagine could be done at the energies the LHC can reach, not experiments that have actually been done.
      2. It's talking about tests of an unusual version of string theory, in which the extra dimensions aren't curled up as tightly as the Planck scale, and string theory starts to show effects at energies on the order of 1 TeV.
      3. They say the experiment could only disprove string theory, not prove it, and then only if the production of microscopic black holes occurred.
      This all seems pretty unexciting to me as a nonspecialist. I mean, heck, if the LHC starts producing microscopic black holes, then obviously quantum gravity becomes a much more reasonable thing to work on, regardless of whether string theory is right or wrong.

      In addition to string theory's problems with non-uniqueness you refer to, it seems to me that there's also a problem with string theory as a theory of quantum gravity, because it assumes a smooth background spacetime with the 3+1 ordinary dimensions being flat. But that's just not a reasonable way for a theory of quantum gravity to work. In particular, there are strong model-independent reasons [wikipedia.org] for believing that spacetime must be discrete, not continuous, at the Planck scale. So even if string theory could have all its other problems taken care of, it would still not be a good candidate for a fundamental theory of quantum gravity.

      [ Parent ]
  • turn into something a bit more substantial than what it is right now, but golly gee whiz, what happens if the the mini black holes don't behave quite exactly like they're supposed to?

  • It depends upon what the definition of a theory is (Score:3, Insightful)

    by jm92956n (758515) on Wednesday February 08 2006, @10:21PM (#14674722) Journal
    I'm confused.

    Evolutionary "theory," for example, has a substantial quantity of data that suggests the general notion is true. But string theory, at least in the scientific community, does not maintain the same support that most other "theories" have. There are, rather, a number of prominent physisists who believe string "theory" doesn't deserve the theoretical status it has obtained (or at least that's what I've been led to believe).

    The question I have, therefore, how was the "theory" part conferred?

    • Re:It depends upon what the definition of a theory (Score:5, Insightful)

      by bunratty (545641) on Wednesday February 08 2006, @10:39PM (#14674815)
      You may not believe this, but the English language is often ambiguous. Some words have two, three, four, or more meanings. The word theory [google.com] is one of those. One definition of theory is a widely tested and accepted set of principles, as in Einstein's theory of relativity, which gives specific predictions about the universe that have been time and again proven correct to a high degree of accuracy. Another definition of theory is a hypothesis that has not yet been verified, as in string theory, which has not been scientifically verified at all. Yes, this ambiguity causes no end of confusion when one refers to the "theory of evolution". Many of us sit back and chuckle as people refer to it as "just a theory".
      [ Parent ]
    • Unfortunately, there is no official body which confers the moniker "theory" to bodies of work which are deserving. Rather, people just call it that so that's how it's known. It is not a theory in the scientific sense. One should really call it String Hy
      • >String theory is not falsifiable

        Assume I have very little understanding of string theory. Could you please explain this in more detail; exactly what part and why string theory is not falsifiable.
            • In that case, this also fits the theory of evolution. Evolution attempts to explain the past, but what predictions does it make of the future than could be checked out by experiment?

              You are joking, right? The Theory of Evolution does not "attempt to explai
              • one doesn't need to wait the 10s of millions of years necessary to see if it happens again.

                The drawback of only having historical data is that there are quite a few holes in that data (IOW the sampling rate is rather low).
                Using this data we don't get to se

      • Re:It depends upon what the definition of a theory (Score:5, Insightful)

        by shawb (16347) on Wednesday February 08 2006, @11:03PM (#14674911) Journal
        One should really call it String Hypothesis or String Postulate.

        In cases like this, untested ideas about the function of the universe, I personally like the term "model." You can use it to posit the inner workings of the universe and why things happen, but untill the technology is there and the experiments have been run it is not fully a scientific theory. But I believe it does fall within the bounds of model. And the nice thing about this is that with a model, you can make some assumptions that may or may not be true to simply explore how the world would work supposing this is true.

        My favorite correlary is light. We have a model of light behaving as a wave, and that model has been proven to be wrong under certain cirumstances. We have a model of light behaving as a particle, and that model can also be proven wrong under certain circumstances. However, the fact that each model is not completely correct does not mean that they are useless. The basis of the model can be used to make further predictions about the way the world works, or even to produce technology through engineering.
        [ Parent ]
    • >how was the "theory" part conferred?

      There is no governing body that certifies theories. Saying something is a theroy does not specify how certain it is, how close it is to the "truth", how popular it is, how accepted it is within a group, how does it
      • > isnt anything that is purported to be true as a result of some a mathematical proof a theorem and something that is known to be true but has no proof a postulate(Law)?

        Notice that "theory" and "theorem" are different words. Theorems arise from applying

  • I predict (Score:3, Funny)

    by Centurix (249778) <mrjolly@optusn e t . c o m . au> on Wednesday February 08 2006, @10:26PM (#14674751) Homepage
    That when they find out that String Theory is String Fact, they'll find out that the string was placed there to keep the nano-kittens occupied.
  • It says "under certain conditions." That is, if I read the article correctly, they have equations which say if the micro-black hole decays in a certain way, it will mean there are more than 11 dimensions.

    Of course, if it doesn't decay as they predict, the
    • Of course, if it doesn't decay as they predict, then their test fails and they've proven nothing about string theory.

      Wrong. It will prove that there are not more than 11 dimensions. It may provide evidence that there are less, or that there are exactly

  • String? (Score:2, Funny)

    by Jarn_Firebrand (845277)
    How is string supposed to predict the amount of dimensions? Do they drop it in a black hole and see how far it goes, and use it from that?


    Sincerely, Confused in the Fifteenth Dimension
  • This is off topic, but last night I was watching a special on string theory on the science channel - another discovery channel. And while it first seemed interesting, about halfway through it I realized it was almost completely devoid of actual informatio
    • Is it my imagination, or does everything on the Discovery channels in the UK seem to be related to either World War II, hurricanes, tornados, crime, accidents? I haven't been able to find anything related to the latest science news. There used to be Discov
      • > Is it my imagination, or does everything on the Discovery channels in the UK seem to be related to either World War II, hurricanes, tornados, crime, accidents?

        A few weeks back Jay Leno observed, "This week in 1933, Adolph Hitler came to power in Germa
        • I had a history professor who called the History Channel "All Hitler, all the time." I found it very funny when I happened to be watching it one night, when they were talking about the history of building roads... and of course talked about Hitler in conj

  • WTF? (Score:3, Funny)

    by Lord_Dweomer (648696) on Wednesday February 08 2006, @10:44PM (#14674840) Homepage
    "which would consist of creating and examining 'micro-black holes', which could be formed by smashing two high energy protons together."

    Since when have we been able to create micro-black holes? Man.....screw lightsabers, i want a gun that shoots micro-black holes!

  • FYI: String Theory per Wikipedia (Score:4, Informative)

    by Sundroid (777083) on Wednesday February 08 2006, @10:46PM (#14674850) Homepage
    From Wikipedia: "String theory is a model of fundamental physics whose building blocks are one-dimensional extended objects (strings) rather than the zero-dimensional points (particles) that are the basis of the Standard Model of particle physics..."

    Here is the article:http://en.wikipedia.org/wiki/String_theory [wikipedia.org]

  • String Theory question (Score:4, Interesting)

    by MSBob (307239) on Wednesday February 08 2006, @11:09PM (#14674928)
    Question for the theoretical physicists in the slashdot crowd:

    If one day string theory is validated by an actual experiment what consequences will it have for the various interpretations of Quantum Mechanics? Is it going to give more credibility to any one of the interpretations of QM? Or is this a completely orthogonal issue?

    Disclaimer: I know nothing about String Theory but methinks that a true Theory of Everything must provide us with an unambiguous answer for the nature of the collapse of a wavefunction, no?

      • well, most physicists do regard wavefunction collapse as more than just a mathematical tool. There appears to be something that really transforms a wave into a stream of particles. we just don't quite understand when and why that happens.

  • Slightly Misleading Title... (Score:4, Informative)

    by Sevaur (780102) on Wednesday February 08 2006, @11:15PM (#14674943)
    Peter Woit, a critic of string theory, points out some of the misleading bits in this article on his blog, "Not Even Wrong: http://www.math.columbia.edu/~woit/wordpress [columbia.edu] (scroll down for it). A brief discussion of why this isn't quite as exciting as it may sound.

    JoAnne Hewett (one of the original authors) also comments in the blog, saying that the journalists tried to make the work a little more accessible by suppressing important details: As for the headline that is blazened on the SLAC home page - I saw it for the first time when someone drew my attention to it. I knew it was going to cause headaches...

    So while this may be solid work, it doesn't seem quite so sexy as it has been made out to be...
  • Yes, but will string theory prevent Xbox 360s from overheating?

  • As scientific theories go... (Score:4, Insightful)

    by MikShapi (681808) on Thursday February 09 2006, @12:14AM (#14675230) Journal
    >> By determining how many dimensions exist, Hewett and Rizzo hope to either confirm or repudiate string theory

    You cannot confirm a theory.
    An experiment can either support it or disprove ("repudiate") it.

  • Scientists never learn (Score:3, Funny)

    by tribentwrks (807384) on Thursday February 09 2006, @01:03AM (#14675397)
    You'd think they'd leave this stuff alone after the "incident" over at the Black Mesa Facility. I think 4 dimensions is plenty for us right now.
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