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Prospects and Limits For the LHC's Capabilities To Test String Theory

Posted by samzenpus on from the proving-it-maybe dept.

StartsWithABang writes: The Large Hadron Collider has just been upgraded, and is now making the highest energy collisions of any human-made machine ever. But even at 13 TeV, what are the prospects for testing String Theory, considering that the string energy scale should be up at around 10^19 GeV or so? Surprisingly, there are a number of phenomenological consequences that should emerge, and looking at what we've seen so far, they may disfavor String Theory after all.

22 of 148 comments (clear)

  1. String Theory\0 by Greyfox · · Score: 4, Funny

    If string theory does end up being proven, they're going to have to be careful not to overwrite the null terminator, or the universe will sigsegv.

    --

    I'm trying to teach myself to set people on fire with my mind... Is it hot in here?

    1. Re:String Theory\0 by rubycodez · · Score: 2

      Fission and fusion bombs produce low energy particles, compared to colliders. Less than a couple dozen million electron volts at most.

    2. Re:String Theory\0 by Coren22 · · Score: 2

      Also, likely a nuclear explosion would have destroyed the detector used to discover the extremely short lived heavy particles.

      --
      APK likes to ask for responses to the same things over and over. Maybe he just likes the responses?
    3. Re:String Theory\0 by idji · · Score: 2

      they were certainly created, but they occur amongst BILLIONS of other events. Part of the magic of the LHC is to ignore all of this and focus only on the interesting EXTREMELY RARE interactions.

    4. Re:String Theory\0 by Anonymous Coward · · Score: 5, Funny

      they were certainly created, but they occur amongst BILLIONS of other events. Part of the magic of the LHC is to ignore all of this and focus only on the interesting EXTREMELY RARE interactions.

      I wish the interactions of your fingers and the shift/caps lock keys were extremely rare.

  2. One quote from the article that is nice... by Hussman32 · · Score: 2, Insightful

    "The production of tiny black holes is one of the predictions. "

    No concerns at all with that one.

    Man I hope they know what they are doing.

    --
    "Who are you?" "No one of consequence." "I must know." "Get used to disappointment."
    1. Re:One quote from the article that is nice... by Coren22 · · Score: 4, Informative

      More energetic collisions happen in the upper atmosphere all the time when cosmic rays enter. If there was concern of black holes eating the earth, it would already have happened.

      Here's some great camera footage at the LHC for you if you are really concerned:

      http://www.cyriak.co.uk/lhc/lh...

      --
      APK likes to ask for responses to the same things over and over. Maybe he just likes the responses?
    2. Re:One quote from the article that is nice... by Hussman32 · · Score: 2

      That webcam is pretty cool, I wonder how long befo

      --
      "Who are you?" "No one of consequence." "I must know." "Get used to disappointment."
  3. Which string theory? by gstoddart · · Score: 2

    Aren't there like 40 things called string theory, ranging from merely odd or unlikely all the way up to batshit crazy?

    I've gotten the sense over the years there's so many things called string theory you can't coherently say what any of it is, or how you'd test it.

    Hell, I'm not even convinced many physicists take it seriously. Which means for the layperson, it mostly sounds like gibberish.

    It just has all the hallmarks of being so unexplainable as to be meaningless. Which I'm sure is grounded in my lack of understanding due to the fact that it's so magical as to be unexplainable.

    --
    Lost at C:>. Found at C.
    1. Re:Which string theory? by gstoddart · · Score: 4, Interesting

      Sure, but ... if Richard Feynmann

      criticized string theory in an interview: "I don't like that they're not calculating anything," he said. "I don't like that they don't check their ideas. I don't like that for anything that disagrees with an experiment, they cook up an explanation--a fix-up to say, 'Well, it still might be true.': These words have since been much-quoted by opponents of the string-theoretic direction for particle physics.

      I'll flat out admit I can't come close to understanding the voodoo which is string theory.

      But that Feynman didn't either, and I've heard more recent quotes from physicists who basically say they don't know what it is either ... I feel I'm in good company.

      I accept that my tiny little money brain isn't up to the task. But I'm not the only one saying "WTF?" about string theory.

      --
      Lost at C:>. Found at C.
    2. Re:Which string theory? by gstoddart · · Score: 2

      Oh, sure. There's a lot of background knowledge required to follow any of it.

      But, honestly, even among people with a reasonable foundation in science ... string theory falls into two camps: a) those who make crazy strange metaphors as if they understand it, and b) those who roll their eyes at the people who use crazy strange metaphors as if they understand it.

      So, I conclude that string theory causes an extreme polarization of dork-ions, a lot of hyperbole, and way too little actual understanding or predictive value to be of much use. ;-)

      --
      Lost at C:>. Found at C.
    3. Re:Which string theory? by Anonymous Coward · · Score: 2, Interesting

      Feynman died in the mid 80s. We've had a good couple of "revolutions" in string theory since. Not that his comments aren't to be taken seriously, but the "string theory" he talked about then is not the "string theory" we talk about now. We now effectively have four or five "string theories" each of which are related to the others via "dualities" (ultimately, ways of transforming aspects of one theory to find exactly aspects of another), and are also related via a duality to supergravity. This both suggests that there is *something* interesting in the theories - be it pure mathematical or be it physical; now that we don't know - and also that there is a single theory that they are the limits of in various regimes. Enter M theory, a "theory" we know nothing about bar its limits in a few different regimes. (We don't know much about what those regimes are, either, merely that they exist.)

      I'm no fan of string theory either, for many of the same reasons. I'm particularly no fan of the bullshit that comes along when "string phenomenologists" take some mathematical aspect, yank it out of context, apply it to some contrived setup in some higher-dimensional form of general relativity, and then pretend that any of this means anything. It doesn't, it means utterly fuck all. The people who instead pick some point of the string landscape and boil it down all the way to 3+1d spacetime are at least doing physics, even if to my knowledge few of them have found anything that suggests that they've got our universe out of it. The phenomenologists are just fucking around.

      But at the same time, there's enough there that I'm happy people are working on it - I just wish that it wasn't such an enormous pit of funding and that other areas of high-energy theoretical physics would get more a look-in. I'm also not happy with the way that high-energy physics is presented to the public. On the one hand, we have people who've seen one Brian Greene documentary and think they know how the universe is set up, and on the other we have *Nobel laureates* giving plenary speakers at major conferences saying stupid, *stupid* fucking things like "We know that supersymmetry is real". No, you stupid fucking cunt, we do *not* know that. This was at a conference in Munich in, hmm, must have been 2008 or 2009. I was very offended even then, and the higher energy the LHC gets to and the increasing bouncing of MSSM parameters to lift them *just* out of range of the LHC, the more pissed off I get. Stupid. Fucking. Stupid. Fucking. Arrogant. CUNT.

      I'm not sure I have a coherent point here :) I just like being able to call a Nobel laureate a stupid fucking cunt, and to advise slight caution against taking Feynman as the last word. A word worth listening to, definitely, but he wasn't talking about quite the same theory as we have now (and he was not, himself, infallible).

    4. Re:Which string theory? by ve3oat · · Score: 2

      Anyone interested in other aspects of this question should read (if they haven't already) "The Trouble with Physics" by Lee Smolin (New York, 2007). He used to be at the Perimeter Institute (maybe still is). Smolin's book isn't just about the physics but also about the sociology of some of the physicists. A good read.

    5. Re:Which string theory? by sjames · · Score: 2

      Actually, quantum mechanics made a few actual predictions that proved to be dead on.

  4. Re:Not a surprise by Coren22 · · Score: 2

    Was that semicolon an indication for putting your sunglasses on?

    --
    APK likes to ask for responses to the same things over and over. Maybe he just likes the responses?
  5. TeV, GeV by wonkey_monkey · · Score: 4, Insightful

    But even at 13 TeV, what are the prospects for testing String Theory, considering that the string energy scale should be up at around 10^19 GeV or so?

    Why the switch to GeV? Stick with a prefix and call it 10^16 TeV.

    --
    systemd is Roko's Basilisk.
  6. a microscopic black hole won't hurt you by ericbg05 · · Score: 4, Informative

    "The production of tiny black holes is one of the predictions. "
    Man I hope they know what they are doing.

    Microscopic black holes disappear quickly due to Hawking radiation. So if your goal is to destroy the earth, creating a microscopic black hole is not the way you want to go.

    The bigger a black hole is, the more slowly it evaporates. So if you want your black hole to do any damage, it'll have to be more than a certain threshold size. Turns out that minimum-size black hole you'll need to destroy Earth is roughly the mass of Mt Everest.

    If we take the density of such a black hole to be 3 * 10^18 kg/m^3, then our black hole will look like a ball with a radius of about 12 cm, i.e. it looks like a soccer ball.*

    See here for more details.

    * no idea if my density assumption is reasonable. I'm not a physicist -- I got the number from 20 seconds of googling. The volume of your black hole may vary.

    1. Re:a microscopic black hole won't hurt you by jfengel · · Score: 2

      It's denser than that. The Schwartzschild radius of a black hole with a mass around 10^15 kg (a rough guess) is about 10^-12 meters (about a picometer). Give or take a few orders of magnitude. Wolfram Alpha has a convenient Schwartzschild radius calculator. The evaporation time for a black hole that big is 10^30 seconds.

      The smaller a black hole is, the denser. The number you give is for a star-sized black hole. There isn't any known way to form grain-of-sand sized black holes, though they might have formed in the very early universe. In which case one could be wandering through the solar system at this very minute....

    2. Re:a microscopic black hole won't hurt you by TechyImmigrant · · Score: 2

      That's fun. A 1 meter radius blackhole would have a mass of around 673500000000000000000000000 Kg

      You could put it in the back of a minivan and drive it around advanced societies, giving the less advanced places time to catch up.

      --
      I should use this sig to advertise my book ISBN-13 : 978-1501515132.
    3. Re:a microscopic black hole won't hurt you by jfengel · · Score: 2

      Found this:

      http://xaonon.dyndns.org/hawki...

      It says that a 3K black hole has a mass of 4x10^22 kg, a bit larger than the Everest-sized black hole.

      The Everest-hole hole is extremely hot, 10^8 K, but it's still radiating so slowly that it'll take 10^21 years to evaporate, so it would be more than enough to destroy the earth.

      I'm not quite sure how to solve for one that would be hot enough to suck in the earth before evaporating, but I see that a black hole that would last 1 second is a mere 70 million kilograms, with a radius of about a picometer.

  7. Re:have lot's of crowbars on hand by fisted · · Score: 2

    ...he was making a game reference, and what he got are unforeseen consequences. Sounds about right to me.

    --
    CLI paste? paste.pr0.tips!
  8. ...and even more inaccurate than usual by Roger+W+Moore · · Score: 4, Interesting

    There are several mistakes in the article as well. Supersymmetry is not a consequence of String Theory. It was invented to explain the huge difference between the Higgs mass and the energy scale where gravity becomes important (the fine-tuning or hierarchy problem). It was only after its invention that String Theorists realized that they needed it to make their theories work. In fact it is entirely possible that Supersymmetry exists and String Theory does not whereas the reverse is far less likely so it is wrong to say that SUSY is a consequence of String Theory.

    Similarly the use of String Theory to solve non-perturbative QCD is not some new, fundamental principle but is simply a result of applying the maths developed for String Theory to a different problem. Hence studying the quark-gluon plasma is, at best, a test of some of the maths developed for String Theory but really tells us nothing at all about the physics. For a simpler analogy if you demonstrate that calculus works this does not imply that Newton's Laws of Motion are correct even though calculus was co-invented by Newton so he could write down and apply his laws.