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The Almighty Buck Science

Why the LHC May Mean the End of Experimental Particle Physics 191

StartsWithABang writes: At the end of the 19th century, Lord Kelvin famously said, "There is nothing new to be discovered in physics now. All that remains is more and more precise measurement." He was talking about how Newtonian gravity and Maxwell's electromagnetism seemed to account for all the known phenomena in the Universe. Of course, nuclear physics, quantum mechanics, general relativity and more made that prediction look silly in hindsight. But in the 21st century, the physics of the Standard Model describes our Universe so well that there truly may be nothing else new to find not only at the LHC, but at any high-energy particle collider we could build here on Earth. If there are no new particles found below about 2–3 TeV in energy—particles that the LHC should detect if they’re present—it’s a reasonable assumption that there might not be anything new to find until energy scales of 100,000,000 TeV or more. And even if we build a particle accelerator to the fullest capacity of our technology around the equator of the Earth, we still couldn’t reach those energies.
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Why the LHC May Mean the End of Experimental Particle Physics

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  • by rockmuelle ( 575982 ) on Friday September 11, 2015 @03:42PM (#50505647)

    Well, if we find a way to measure either of those using high-energy experiments, we'll get a few more decades out of the field.

    Just when we think we're done, we're usually just at the beginning...

    -Chris

    • by VernonNemitz ( 581327 ) on Friday September 11, 2015 @04:15PM (#50505879) Journal
      The original article clearly indicates that such particles need to be found first, within the abilities of the LHC. OR, we need something bigger than the Earth's circumference [halfbakery.com].
      • Except they are talking out of their ass. They don't know for certain, not at all. It's all supposition.

        • by Ramze ( 640788 ) on Saturday September 12, 2015 @01:50AM (#50508467)

          Actually, you have that a bit backwards. The Standard Model says we're done finding new particles. The Higgs was the last one we expected to find, and it was so necessary to the theory that we could describe all of its attributes long before we actually found it. When we did, it matched the theory perfectly -- too perfectly. We knew its mass, spin, decay rate, and interaction with other particles just from the math before we even found it in the lab. Physicists were both relieved and saddened by the discovery as it meant the standard model was correct and there were no new physics to be found.

          It's the idea of finding new particles that is all supposition. We know the standard model can't explain everything, but we don't know that missing particles are the solution. We also don't know how to detect those new particles if they do exist. Gravitons, sterile neutrinos, and black matter particles (whatever those may be) would be electrically neutral and barely interact with anything -- much less a particle detector. We suspect we will be able to detect them indirectly if they exist at all. There is a slim chance that there may be more than one type of Higgs, but other Higgs are not necessary for the theory to work and other Higgs would be at much higher energy levels.

          You are correct that no one knows for certain -- that's the whole reason they conduct the experiments. But, the very well known math and theory strongly suggest that we're done. It's the wild supposition arguments that hope there's something more.

          And that's not because they don't WANT to find new physics... it's just... quantum mechanics and particle physics are so well understood that it would be extremely surprising to find other fundamental particles -- b/c if they exist, they must be very very weakly interacting with all the known particles or at least very short lived to not cause chaos with the currently understood theory.

      • False.

        The universe can produce ZeV range particles 10^21, already there are experiments in the works to detect dark matter decays from cosmic rays. Turns out we only need very sensitive detectors for expected decay products.

        • Shhh!

          It is a secret, we need to build more colliders to, you know, watch shit collide and go up in sparks.

          Are you with us nerds or with senator Proxmire?

  • Citation needed (Score:4, Insightful)

    by belrick ( 31159 ) on Friday September 11, 2015 @03:43PM (#50505659) Homepage

    In the article this: "it’s a reasonable assumption that there might not be anything new to find until energy scales of 100,000,000 TeV or more. " is asserted without supporting evidence.

    • Re:Citation needed (Score:5, Interesting)

      by jfengel ( 409917 ) on Friday September 11, 2015 @04:17PM (#50505905) Homepage Journal

      The idea is that if we don't find anything, the next most likely place to go looking is at the energy where the strong, weak, and electrical forces unify, around 10^13 TeV. The number they give is a few orders of magnitude below that; we probably wouldn't have to get all the way to the grand unification energy [wikipedia.org] to see hints of new particles. I think that's the evidence you're looking for; it's justified by our present theory.

      It's a "reasonable assumption" in that those theories begin to break down at that scale. We expect our theories to hold quite well, which would mean that we wouldn't expect to find anything novel until we got close. And then we have every reason to expect to find new things, which is what you need to help drive a theory that's measurably different from our present one.

      Of course we never know what we'll find, but it would be hard to build any sort of intermediate-sized collider, which would cost insane amounts of money, and theory predicts that it wouldn't find anything of value unless it were even bigger. It could be even worse; they might not find anything for a few more orders of magnitude, at which point they'd be probing not just the strong, weak, and electrical forces, but also gravity. We know for certain that the theory breaks down there, but the amount of energy required to probe the breakdown is simply ludicrous.

    • by Roger W Moore ( 538166 ) on Friday September 11, 2015 @04:31PM (#50506009) Journal
      There is a good reason for that - there is no supporting evidence and, in fact, very strong evidence suggesting that it is completely wrong...but that's what you get with 'startswithabang', it usually ends with a whimper. The one of the most damning bits of evidence that there is something well before 10^19 GeV (no clue where he gets the 1^8 TeV figure from) is that the Higgs mass 125 GeV/c^2.

      Unlike every other fundamental particle the Higgs has no spin, which means it has no intrinsic angular momentum like electrons, quarks, photons etc. This has the effect that quantum corrections very strongly affect its mass. In fact these corrections apply to the square of the Higgs mass and grow as the square of the energy scale so if the Standard Model is good up to the Planck scale at 10^19 GeV these corrections are of the order of 10^38 in size. Each Standard Model particle has its own correction to the Higgs mass with fermions and bosons providing opposite sign corrections.

      Here is the problem though. In the Standard Model there is no symmetry between fermions and bosons and the coupling to the Higgs field, which determines these corrections, are all free parameters. So if we believe that there is nothing but the Standard Model before the Planck scale then we have an amazing co-incidence that a series of essentially random terms each of order 10^38 cancel so precisely that the remainder is of order 10^4.

      To put that in context it would be like tossing a coin about 100 billion times and getting heads every single time. I don't know about you but personally I would start getting suspicious that something was fixing the result sometime around toss 100.

      This is the issue with the Standard Model: the fact that there is a Higgs at 125 GeV is like the 100 billion coin tosses all coming up heads. The problem is that we do not yet know how nature is fixing the result but it does mean that the new physics required to fix it most likely occurs below ~10 TeV. While this is not a hard limit the higher in energy you go the less natural any accidental cancellation will be so really the energy limit where you expect new physics depends on how many times you can toss a coin and get heads before you believe that something is fixing the result.
      • by Compuser ( 14899 )

        I think the limiting factor is going to be financial. Nobody will be building single purpose science facilities at a cost which is a significant fraction of the GDP. My guess is that something on the scale of $10-20B is imaginable (i.e. something like the failed SSC) but much bigger is not. Now, couple this with the fact that CERN was only able to sell their expansion due to the hunt for Higgs. This was not some nebulous cancellation of perturbative corrections but a very real prize which could then for yea

        • I think the limiting factor is going to be financial.

          That's one way to look at it but I prefer to think that the limiting factor is really cleverness. The techniques we use in the LHC to accelerate particles are fundamentally the same as those used since the 1930's albeit with significant, incremental improvements. We have indeed reached the financial limit of current accelerator technology but there are alternatives.

          One way, as you suggest, would be to go for new acceleration techniques. Plasma physicists have had some impressive results with particle ac

    • In the article this: "it’s a reasonable assumption that there might not be anything new to find until energy scales of 100,000,000 TeV or more. " is asserted without supporting evidence.

      Solid state physics has plenty to look at and it doesn't need things to be that hot. More commonly it needs things to be cold.

    • This was common assumption in the physics world for at least 20 years.
  • Turn it up to eleven.

  • And even if we build a particle accelerator to the fullest capacity of our technology around the equator of the Earth, we still couldn’t reach those energies.

    ...within the context of currently understood science and technology.

    Which is exactly the same contextual caveat Lord Kelvin failed to incorporate in his thinking.

    Here's your money quote: Until we know everything, we don't know everything. And I assure you, we don't know everything.

    --me

    • Well, the point is not there isn't anything else to discover, the point is at which energy levels we can expect to find something. His assumption is based on the current theories and at which energy levels we can hope to find something. There is no reason we should observe particles at all energies and an energy desert is very likely and plausible. So, should we invest ressources, money and energy into the business of searching new particles at all energy levels without at least some indication they exists?

      • by fyngyrz ( 762201 )

        You missed my point. His quote is based upon the current technologies we have to accelerate particles.

  • As there very well may be some dark matter (one of several types of non-baryonic matter), left for us to investigate. The LHC and it's ilk simply can not detect dark matter.
  • TFA isn't saying that there might be no new particles. High energy physicists agree that there have to be new particles. TFA is saying that there will be new particles, but they may be almost impossible to find. That would be a bummer, but such is life. I think it's amazing that we've been able to probe such small length scales, but there are limits to what we can do given our resources.

  • When we look back from the year 5000, the years between 1800 and 1980 will stand out as the time period during which we figured out the main fundamental science to understand how the world around us works. We are not at the end of particle physics. There will be lots more to learn from higher energy and higher luminocity colliders, as well as studies of extremely high energy cosmic rays and astronomical data. But even if a bunch of new particles with masses in the TeV range are found, they won't change t
    • Your paucity of imagination beggars mine.

    • Seriously, Lord Rutherford, didn't you predict that physics was essentially complete around 1900? Sure, there were a few things not yet understood, like Mercury's orbit, the results of the Michelson-Morley experiment, black-body radiation, that sort of thing, but it certainly wasn't going to upset physics.

      I assume you also agree that, even if there is some new physics that might explain black-body radiation and the photoelectric effect, that it can't possibly have practical applications, dealing with th

      • by ganv ( 881057 )

        I recommend you read the history more carefully. In 1900 the best scientists knew that they did not understand what matter was or why it had such strange spectra (Kelvin even spent quite a bit of effort trying to develop vortex descriptions of atoms.) They knew that they didn't know where the sun's energy came from. They knew that they knew almost nothing about how cells worked. But surprisingly, it turns out that they already did know most of what we currently think is important to teach to engineerin

        • Sure, physics around 1900 had some holes in knowledge, and Lord Rutherford acknowledged that while claiming that most of the work was done. He expected some sort of resolution on things like the photoelectric effect and the orbit of Mercury that would more or less conform with the physics he knew. I'm using him as an example of an eminent scientist who said a stupid thing through failure of imagination.

          I don't understand why in one paragraph you claim that most engineering uses science as Rutherford kn

  • And yet physics cannot explain consciousness - seems like we have quite a way to go. (Although quantum mechanics seems to tell us that consciousness and reality are somehow linked - seems like there might be quite a bit to explore there.) And we still do not understand our where our universe sits in the total scheme of things - are we in a black hole? And do we really think that there is no new physics in the range of size down to the Plank length? For those who think that we know a-lot about reality, I rec
  • ... particles that the LHC should detect if they’re present ...

    If only this thing could collide and detect small and medium hadrons.

  • The summary is obviously full of holes, because there are plans to make matter/antimatter colliders that would harness way more energy. So yes we have identified a need, and we know that the Standard Model is incomplete and needs more work. Saying there is nothing new to discover truly lacks a scientific imagination. This is the same sort of bs that prevented the LHC or equivalent from being constructed in the US: "Will we find the 'God' particle?"
  • Neutrinos (Score:5, Informative)

    by Framboise ( 521772 ) on Friday September 11, 2015 @04:29PM (#50505997)

    Has this guy never heard that the mere fact neutrinos have a mass does not fit in the Standard Model, and that plenty of good experimental physics can be made on these particles?

    • by Ramze ( 640788 )

      Neutrinos with mass certainly DO fit in the Standard Model. In fact, all 3 known left-handed neutrinos are a part of the standard model. Neutrinos are even known to oscillate between the 3 types. Originally, neutrinos were assumed to be massless as their mass is so incredibly tiny it couldn't be detected when the particles were first proposed and discovered. Their insignificant mass didn't alter any predictions the model made on particle physics at the time. That does not mean that they aren't more

  • Why the LHC May Mean the End of Experimental Particle Physics

    But Probably Won't, So Shut Up?

    If there are no new particles found below about 2–3 TeV in energy—particles that the LHC should detect if they’re present—it’s a reasonable assumption that there might not be anything new to find until energy scales of 100,000,000 TeV or more.

    So they're going to stop looking on the basis of a "reasonable assumption"? Not how science works, last time I checked.

    Perhaps it should have been "Why the LHC may mean the next few years or even centuries of experimental particle physics might be a bit less exciting."

    • by jo_ham ( 604554 )

      The title is obvious nonsense, but the "reasonable assumption" is the Standard Model.

      • Surely a good way to test reasonable assumptions and make them even more reasonable (or overturn them) is to check all the places the assumption tells you not to bother looking.

        • by jo_ham ( 604554 )

          In normal scientific terms, yes, but the Standard Model, especially now that the Higgs has finished the puzzle, is as pretty close to "here's a map of where you'll find each particle within these ranges" as you're likely to see. The next range is also quite generally defined by the nuclear forces, and it's considerably higher than anything we can reasonably do right now (i.e., nowhere close even if we build an accelerator that circles the earth's equator.

  • I remember going to a talk around 2003 where the upper limit of particle smashers was discussed by radius and compared to theoretical energy values for various particles. It's a known problem - and there have been (expensive) suggestions put forth for years.

    • This is why paywalls suck:

      https://www.scientificamerican.com/article/the-amateur-scientist-1989-04/

      This article describes the solution.

  • One year after confirming the existence of the Higgs Boson, or “God Particle,” scientists at CERN say they are struggling to find other uses for the giant particle accelerator. http://www.theonion.com/video/... [theonion.com]

  • _EVERY_ time somebody says "There's nothing new to be learned", within a few years we discover that there are vast realms of reality that we had never suspected might exist. Between "string theory" and "dark matter" and "dark energy", there are enough assumptions and hand-waving to make me think that we're about at that stage again.

    "Real Soon Now", we're going to discover that the current generations of physics professors have been chasing after imaginary rabbits and that reality is very different. Our und

    • _EVERY_ time somebody says "There's nothing new to be learned",

      That's great, but that's not what the article says.

      It says we don't know how to build the machine that will demonstrate the new stuff.

  • First of all... this is the first article in a REALLY long time on Slashdot where I've seen genuine intelligence being applied in the comments. There are absolutists, nay-sayers, pragmatists and more here and I swear, I feel like I've grown smarter from the comments which is just so rare for most articles. So... thank you everyone for contributing to my personal education, I mean this wholeheartedly.

    I've seen many comments that make many good points.

    We have the obvious which is "using LHC technology, scalin
    • ... thing about a spool ...

      A spool won't help. It's not the length that matters, it's the radius of curvature.

      Basically, accelerating electrons make changing electromagnetic fields and that means they produce photons. The charged particles zipping round the circular path emit radiation since that's constant acceleration. The smaller the curve and the faster they go, the more they emit. The energy released like that is what determines the maximum speed. Once the radation out matches the energy in, they go n

  • (who had some damned wise things to say about a LOT of stuff .. curiously enough even the LHC:

    http://www.brainyquote.com/quo... [brainyquote.com]

    "If an elderly but distinguished scientist says that something is possible, he is almost certainly right; but if he says that it is impossible, he is very probably wrong."

  • Almost every article has tons of assumptions, lots of hand waving, refuses to correct mistakes even when pointed out, etc.

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