What if the Large Hadron Collider Finds Nothing Else?

In my last post, I expressed the view that a particle accelerator with proton-proton collisions of (roughly) 100 TeV of energy, significantly more powerful than the currently operational Large Hadron Collider [LHC] that helped scientists discover the Higgs particle, is an obvious and important next steps in our process of learning about the elementary workings of nature. And I described how we don’t yet know whether it will be an exploratory machine or a machine with a clear scientific target; it will depend on what the LHC does or does not discover over the coming few years.

What will it mean, for the 100 TeV collider project and more generally, if the LHC, having made possible the discovery of the Higgs particle, provides us with no more clues?  Specifically, over the next few years, hundreds of tests of the Standard Model (the equations that govern the known particles and forces) will be carried out in measurements made by the ATLAS, CMS and LHCb experiments at the LHC. Suppose that, as it has so far, the Standard Model passes every test that the experiments carry out? In particular, suppose the Higgs particle discovered in 2012 appears, after a few more years of intensive study, to be, as far the LHC can reveal, a Standard Model Higgs — the simplest possible type of Higgs particle?

Before we go any further, let’s keep in mind that we already know that the Standard Model isn’t all there is to nature. The Standard Model does not provide a consistent theory of gravity, nor does it explain neutrino masses, dark matter or “dark energy” (also known as the cosmological constant). Moreover, many of its features are just things we have to accept without explanation, such as the strengths of the forces, the existence of “three generations” (i.e., that there are two heavier cousins of the electron, two for the up quark and two for the down quark), the values of the masses of the various particles, etc. However, even though the Standard Model has its limitations, it is possible that everything that can actually be measured at the LHC — which cannot measure neutrino masses or directly observe dark matter or dark energy — will be well-described by the Standard Model. What if this is the case?

Michelson and Morley, and What They Discovered

In science, giving strong evidence that something isn’t there can be as important as discovering something that is there — and it’s often harder to do, because you have to thoroughly exclude all possibilities. [It’s very hard to show that your lost keys are nowhere in the house — you have to convince yourself that you looked everywhere.] A famous example is the case of Albert Michelson, in his two experiments (one in 1881, a second with Edward Morley in 1887) trying to detect the “ether wind”.

Light had been shown to be a wave in the 1800s; and like all waves known at the time, it was assumed to be a wave in something material, just as sound waves are waves in air, and ocean waves are waves in water. This material was termed the “luminiferous ether”. As we can detect our motion through air or through water in various ways, it seemed that it should be possible to detect our motion through the ether, specifically by looking for the possibility that light traveling in different directions travels at slightly different speeds.  This is what Michelson and Morley were trying to do: detect the movement of the Earth through the luminiferous ether.

Both of Michelson’s measurements failed to detect any ether wind, and did so expertly and convincingly. And for the convincing method that he invented — an experimental device called an interferometer, which had many other uses too — Michelson won the Nobel Prize in 1907. Meanwhile the failure to detect the ether drove both FitzGerald and Lorentz to consider radical new ideas about how matter might be deformed as it moves through the ether. Although these ideas weren’t right, they were important steps that Einstein was able to re-purpose, even more radically, in his 1905 equations of special relativity.

In Michelson’s case, the failure to discover the ether was itself a discovery, recognized only in retrospect: a discovery that the ether did not exist. (Or, if you’d like to say that it does exist, which some people do, then what was discovered is that the ether is utterly unlike any normal material substance in which waves are observed; no matter how fast or in what direction you are moving relative to me, both of us are at rest relative to the ether.) So one must not be too quick to assume that a lack of discovery is actually a step backwards; it may actually be a huge step forward.

Epicycles or a Revolution?

There were various attempts to make sense of Michelson and Morley’s experiment.   Some interpretations involved  tweaks of the notion of the ether.  Tweaks of this type, in which some original idea (here, the ether) is retained, but adjusted somehow to explain the data, are often referred to as “epicycles” by scientists.   (This is analogous to the way an epicycle was used by Ptolemy to explain the complex motions of the planets in the sky, in order to retain an earth-centered universe; the sun-centered solar system requires no such epicycles.) A tweak of this sort could have been the right direction to explain Michelson and Morley’s data, but as it turned out, it was not. Instead, the non-detection of the ether wind required something more dramatic — for it turned out that waves of light, though at first glance very similar to other types of waves, were in fact extraordinarily different. There simply was no ether wind for Michelson and Morley to detect.

If the LHC discovers nothing beyond the Standard Model, we will face what I see as a similar mystery.  As I explained here, the Standard Model, with no other particles added to it, is a consistent but extraordinarily “unnatural” (i.e. extremely non-generic) example of a quantum field theory.  This is a big deal. Just as nineteenth-century physicists deeply understood both the theory of waves and many specific examples of waves in nature  and had excellent reasons to expect a detectable ether, twenty-first century physicists understand quantum field theory and naturalness both from the theoretical point of view and from many examples in nature, and have very good reasons to expect particle physics to be described by a natural theory.  (Our examples come both from condensed matter physics [e.g. metals, magnets, fluids, etc.] and from particle physics [e.g. the physics of hadrons].) Extremely unnatural systems — that is, physical systems described by quantum field theories that are highly non-generic — simply have not previously turned up in nature… which is just as we would expect from our theoretical understanding.

[Experts: As I emphasized in my Santa Barbara talk last week, appealing to anthropic arguments about the hierarchy between gravity and the other forces does not allow you to escape from the naturalness problem.]

So what might it mean if an unnatural quantum field theory describes all of the measurements at the LHC? It may mean that our understanding of particle physics requires an epicyclic change — a tweak.  The implications of a tweak would potentially be minor. A tweak might only require us to keep doing what we’re doing, exploring in the same direction but a little further, working a little harder — i.e. to keep colliding protons together, but go up in collision energy a bit more, from the LHC to the 100 TeV collider. For instance, perhaps the Standard Model is supplemented by additional particles that, rather than having masses that put them within reach of the LHC, as would inevitably be the case in a natural extension of the Standard Model (here’s an example), are just a little bit heavier than expected. In this case the world would be somewhat unnatural, but not too much, perhaps through some relatively minor accident of nature; and a 100 TeV collider would have enough energy per collision to discover and reveal the nature of these particles.

Or perhaps a tweak is entirely the wrong idea, and instead our understanding is fundamentally amiss. Perhaps another Einstein will be needed to radically reshape the way we think about what we know.  A dramatic rethink is both more exciting and more disturbing. It was an intellectual challenge for 19th century physicists to imagine, from the result of the Michelson-Morley experiment, that key clues to its explanation would be found in seeking violations of Newton’s equations for how energy and momentum depend on velocity. (The first experiments on this issue were carried out in 1901, but definitive experiments took another 15 years.) It was an even greater challenge to envision that the already-known unexplained shift in the orbit of Mercury would also be related to the Michelson-Morley (non)-discovery, as Einstein, in trying to adjust Newton’s gravity to make it consistent with the theory of special relativity, showed in 1913.

My point is that the experiments that were needed to properly interpret Michelson-Morley’s result

  • did not involve trying to detect motion through the ether,
  • did not involve building even more powerful and accurate interferometers,
  • and were not immediately obvious to the practitioners in 1888.

This should give us pause. We might, if we continue as we are, be heading in the wrong direction.

Difficult as it is to do, we have to take seriously the possibility that if (and remember this is still a very big “if”) the LHC finds only what is predicted by the Standard Model, the reason may involve a significant reorganization of our knowledge, perhaps even as great as relativity’s re-making of our concepts of space and time. Were that the case, it is possible that higher-energy colliders would tell us nothing, and give us no clues at all. An exploratory 100 TeV collider is not guaranteed to reveal secrets of nature, any more than a better version of Michelson-Morley’s interferometer would have been guaranteed to do so. It may be that a completely different direction of exploration, including directions that currently would seem silly or pointless, will be necessary.

This is not to say that a 100 TeV collider isn’t needed!  It might be that all we need is a tweak of our current understanding, and then such a machine is exactly what we need, and will be the only way to resolve the current mysteries.  Or it might be that the 100 TeV machine is just what we need to learn something revolutionary.  But we also need to be looking for other lines of investigation, perhaps ones that today would sound unrelated to particle physics, or even unrelated to any known fundamental question about nature.

Let me provide one example from recent history — one which did not lead to a discovery, but still illustrates that this is not all about 19th century history.

An Example

One of the great contributions to science of Nima Arkani-Hamed, Savas Dimopoulos and Gia Dvali was to observe (in a 1998 paper I’ll refer to as ADD, after the authors’ initials) that no one had ever excluded the possibility that we, and all the particles from which we’re made, can move around freely in three spatial dimensions, but are stuck (as it were) as though to the corner edge of a thin rod — a rod as much as one millimeter wide, into which only gravitational fields (but not, for example, electric fields or magnetic fields) may penetrate.  Moreover, they emphasized that the presence of these extra dimensions might explain why gravity is so much weaker than the other known forces.

Fig. 1: ADD's paper pointed out that no experiment as of 1998 could yet rule out the possibility that our familiar three dimensional world is a corner of a five-dimensional world, where the two extra dimensions are finite but perhaps as large as a millimeter.

Fig. 1: ADD’s paper pointed out that no experiment as of 1998 could yet rule out the possibility that our familiar three-dimensional world is a corner of a five-dimensional world, where the two extra dimensions are finite but perhaps as large as a millimeter.

Given the incredible number of experiments over the past two centuries that have probed distances vastly smaller than a millimeter, the claim that there could exist millimeter-sized unknown dimensions was amazing, and came as a tremendous shock — certainly to me. At first, I simply didn’t believe that the ADD paper could be right.  But it was.

One of the most important immediate effects of the ADD paper was to generate a strong motivation for a new class of experiments that could be done, rather inexpensively, on the top of a table. If the world were as they imagined it might be, then Newton’s (and Einstein’s) law for gravity, which states that the force between two stationary objects depends on the distance r between them as 1/r², would increase faster than this at distances shorter than the width of the rod in Figure 1.  This is illustrated in Figure 2.

Fig. 2: If the world were as sketched in Figure 1, then Newton/Einstein's law of gravity would be violated at distances shorter than the width of the rod in Figure 1.  The blue line shows Newton/Einstein's prediction; the red line shows what a universe like that in Figure 1 would predict instead.  Experiments done in the last few years agree with the blue curve down to a small fraction of a millimeter.

Fig. 2: If the world were as sketched in Figure 1, then Newton/Einstein’s law of gravity would be violated at distances shorter than the width of the rod in Figure 1. The blue line shows Newton/Einstein’s prediction; the red line shows what a universe like that in Figure 1 would predict instead. Experiments done in the last few years agree with the blue curve down to a small fraction of a millimeter.

These experiments are not easy — gravity is very, very weak compared to electrical forces, and lots of electrical effects can show up at very short distances and have to be cleverly avoided. But some of the best experimentalists in the world figured out how to do it (see here and here). After the experiments were done, Newton/Einstein’s law was verified down to a few hundredths of a millimeter.  If we live on the corner of a rod, as in Figure 1, it’s much, much smaller than a millimeter in width.

But it could have been true. And if it had, it might not have been discovered by a huge particle accelerator. It might have been discovered in these small inexpensive experiments that could have been performed years earlier. The experiments weren’t carried out earlier mainly because no one had pointed out quite how important they could be.

Ok Fine; What Other Experiments Should We Do?

So what are the non-obvious experiments we should be doing now or in the near future?  Well, if I had a really good suggestion for a new class of experiments, I would tell you — or rather, I would write about it in a scientific paper. (Actually, I do know of an important class of measurements, and I have written a scientific paper about them; but these are measurements to be done at the LHC, and don’t involve a entirely new experiment.)  Although I’m thinking about these things, I do not yet have any good ideas.  Until I do, or someone else does, this is all just talk — and talk does not impress physicists.

Indeed, you might object that my remarks in this post have been almost without content, and possibly without merit.  I agree with that objection.

Still, I have some reasons for making these points. In part, I want to highlight, for a wide audience, the possible historic importance of what might now be happening in particle physics. And I especially want to draw the attention of young people. There have been experts in my field who have written that non-discoveries at the LHC constitute a “nightmare scenario” for particle physics… that there might be nothing for particle physicists to do for a long time. But I want to point out that on the contrary, not only may it not be a nightmare, it might actually represent an extraordinary opportunity. Not discovering the ether opened people’s minds, and eventually opened the door for Einstein to walk through. And if the LHC shows us that particle physics is not described by a natural quantum field theory, it may, similarly, open the door for a young person to show us that our understanding of quantum field theory and naturalness, while as intelligent and sensible and precise as the 19th century understanding of waves, does not apply unaltered to particle physics, and must be significantly revised.

Of course the LHC is still a young machine, and it may still permit additional major discoveries, rendering everything I’ve said here moot. But young people entering the field, or soon to enter it, should not assume that the experts necessarily understand where the field’s future lies. Like FitzGerald and Lorentz, even the most brilliant and creative among us might be suffering from our own hard-won and well-established assumptions, and we might soon need the vision of a brilliant young genius — perhaps a theorist with a clever set of equations, or perhaps an experimentalist with a clever new question and a clever measurement to answer it — to set us straight, and put us onto the right path.

82 responses to “What if the Large Hadron Collider Finds Nothing Else?

  1. Matt, I have them both, equations and experiment. I have four physicists with me and we start our collaboration next Monday. Very exciting indeed!

    • Richard Bauman

      What great fun. Sure wist I was young enough to be one of you. May I suggest that you take a little extra time to look around. So many things seem wrong today that maybe something really new and different should at least be looked at first. Example; the idea that all praticles are built from 3 preons. Some what like string theory but here each preon is one dimensional. But just get some different ideas than what is accepted today. Well best of luck to all five of you !

  2. For some resolutions of these problems see these papers: https://independent.academia.edu/GeorgeRaina/Papers

  3. Maybe they should have not been so involved with the Etheric model but more thoughtful ( as per Newton ) about the mechanism of space itself with or without the Aether? If one thinks of space as nothing but a container for something could be a short sighted doctrine as the container in this case maybe subject to its own strict mechanism which we have not yet even got close to realizing? With a unity dimension.

  4. thetasteofscience

    Brilliant post!

  5. thetasteofscience

    Reblogged this on thetasteofscience and commented:
    Comparing Michael-Morley to the current state of particle physics lents a wonderful insight!

  6. Thank you for speaking bluntly about this uncomfortable but interesting scenario of no physics beyond thenStandard Model at LHC and trying to draw prospects from such an alternative.
    Your discussion about the Michelson experiment which more or less rejected the existence of a classical ether is on purpose from an epistemological point of view. But as far as heuristics is concerned, it is quite ironical to notice that the discovery of a pretty standard, fundamental scalar Higgs boson puts the existence of its quantum field and specific non zero vacuum expectation value on a firm basis, so it demonstates the existence of a very special quantum ether, some kind of “space condensate” so to speak (a wink to condensed matter phenomena which inspired the conception of the Higgs mechanism) ! So before looking for new fundamental particles may be high energy physicists definitely need to fully understand the Higgs at the TeV scale (with a Higgs factory accelerator) and extrapolate all the possible consequences of the associated “space condensate” up to Planck scale … and try to test them in a cosmological context (inflation model) with the measures of … the Planck sattelite!

    • Yes, there is some irony in that, I agree… but still, the “space-time condensate” (not a space-condensate) that is the Higgs field fits right in with the odd story of an ether which is at rest with respect to everyone, no matter how they are moving. This is in contrast to the condensed matter physicists who had a space-condensate with respect to which you can be moving.

      There’s no question that we need to understand the Higgs thoroughly, and of course that is a major part of the LHC research program. But we already know enough about quantum field theory to know that there’s a conceptual problem if nothing else shows up at the LHC.

      • laboussoleestmonpays

        Thanks for your addendum! The time dimension is very relevant indeed: what would be physics without causality and its “thermodynamic handmaiden” stability (another intriguing aspect of the Higgs vacuum by the way)?
        To carry on the fact that “ideas developed in the condensed matter field can prove useful in particle physics” (to quote more or less S. Weinberg http://cerncourier.com/cws/article/cern/32522 :-), do you think the following line of reasoning : “stability conditions in solid state physics … are known, in certain cases, to cause UV divergences to sum automatically to zero” (quoted from http://arxiv.org/abs/1106.6354) has any chance to be relevant in the context of the quadratic divergences in the Higgs sector?

        • laboussoleestmonpays

          To put equations (not mine!) behind “space condensate” (my awkward words) I precise that I have in mind the specific mathematical model patiently refined since twenty years by a mathematician A. Connes with severa theoretical physicsts like A. Chamseddine, M. Marcolli and P. van Suijlekom (http://arxiv.org/abs/1304.8050, http://arxiv.org/abs/hep-th/9706200) which does not pretend to solve the naturalness issue of the Higgs (it’s not their main strategy I would say) but try to give more conceptual meaning to the Standard Model Yang-Mills-Higgs gauge structure … may be like special relativity explained the hidden Lorentz symmetry of space-time ;-)

      • Have you considered the possibility that the Higgs field is a different manifestation of quantum gravity at high energy levels and for that reason it behaves like the aether?

  7. 1. The problem with this post is that you can read it once again with replacing the 100 TeV with 200 TeV and nothing is going to change, go on once again replace the 200 TeV with 500 TeV and … stop it, go back now, and replace the 100 TeV with 14 TeV and read it again.

    Where is the X for which every particle physicist – both theoretical and experimental would accept, that if at the X TeV LHC nothing beyond the Standard Model was found, we are done ?

    2. “What if the Large Hadron Collider Finds Nothing Else?” – no problem for the 2015 run LHC, but if the 100 TeV LHC would find nothing, it will block the HEP foundations for a long time, and the project itself would be labeled as the most expensive “nothing” ever. The worst is that it is not even definite “nothing”, there would be always somebody saying “look at higher energies – just behind the corner”. It would be nearly impossible to explain for a non-professional, while this “nothing” was worth the bills.

    I would now break a little bit with building brute force colliders and focus the efforts and resources to research and development the technology to build muon collider – to lower the noise in the data, and support many-many more subtil, more focused experiments. We should collect and develop more concrete goals and outputs with definitive “yes” or “no” as it is in the mentioned Michelson and Morley experiment, and then go on with high energies by building a Large Muon Collider.

    • Correction, should be:

      Where is the lowest X for which every particle physicist …

    • I feel that your first paragraph is incorrect… and crucially so.

      “The problem with this post is that you can read it once again with replacing the 100 TeV with 200 TeV and nothing is going to change, go on once again replace the 200 TeV with 500 TeV and … stop it, go back now, and replace the 100 TeV with 14 TeV and read it again.”

      I agree with you until the last line, when I’d argue that you make a fundamental error. No, the 7-to-14 TeV machine is qualitatively different. We have known since 1933 about the weak nuclear force and the fact that the TeV scale is a crucial one for understanding the weak nuclear force. People didn’t know about the structure of the proton then, so they wouldn’t specifically have suggested a 14 TeV proton-proton collider, but they already knew that someday it would be important to explore the TeV scale. So the 14 TeV machine has been well-motivated — in the language of my last post, http://profmattstrassler.com/2014/03/03/a-100-tev-proton-proton-collider/ , it was a machine with a known target — for decades. That’s why the SSC was designed to be a 40 TeV machine. It had a clear target and was an easier way to reach it than the LHC is.

      As for the other machines — as I emphasized in Monday’s post — we do not know yet if they will have a target or if they will be exploratory. If the LHC finds nothing, then they will be exploratory, and then I agree; 100 TeV, 200 TeV, 300… these are arbitrary goalposts, set by technology and not by a clear target This is exactly why we need to have open minds and look broadly for other types of experiments we can do.

      Moreover — your second paragraph — we already know the STandard Model is not everything, and we know that we are not done. That’s why there’s a whole discussion in this post about gravity, dark matter, dark energy, the strengths of the forces… So the answer is that there will absolutely be no X when we think we’re done, until the already-known mysteries are solved.

      As for your point 2: a muon collider is likely to be even more expensive than the 100 TeV proton-proton machine, may not even work, and it is not clear it has a target either. I’d be happy to have a muon collider, but Im not sure I see why it would address the issues with the 100 TeV proton machine.

  8. Markus Harder

    Matt, well done, I think your post is a broad and balanced view that considers various directions of further research, some following the established collider path with higher energy and more precision, but also those paths that need a completely new vision.
    One question and one comment:
    1.) Question: I did not understand why on one hand you write “the Standard Model, with no other particles added to it, is a consistent but extraordinarily “unnatural” [...] quantum field theory”, but shortly afterwards you consider it possible that “our understanding of particle physics requires an epicyclic change — a tweak” (a minor modification). But doesn´t a tweak mean that the model is only slightly – and not extraordinarily – unnatural? I did not get the idea how an extremely strange model might be fixed with only a minor tweak.
    2.) Comment: Concerning the Michelson-Morley experiment, I find it a bit misleading to present it as the search for the aether and then they found – nothing. The aether was a theoretical concept. But what was really measured in the experiments was the speed of light in different directions, and the result was that the speed of light was the same for all directions. I consider it a bit misleading to describe this as if they found nothing (or no aether). And when it comes to a generalization of the experimental results, one could say they have found (experimental proof of) the constance of the speed of light (roughly speaking). This is rather something and not nothing that came out of the experiments. My intention here is not to play with the wording, but I am not sure if the LHC results and the Michelson-Morley experiments have too much in common. Or maybe they have, but then someone still needs to find a way to understand a (hypothetical) lack of particles not just as a lack but as the discovery of a new principle or concept.

    • 1) Good question. The Standard Model is extremely unnatural. The Supersymmetric version of the Standard Model (where all known particles are accompanied by superpartner particles with masses not far from 1 TeV/c^2) is a natural theory. See http://profmattstrassler.com/articles-and-posts/some-speculative-theoretical-ideas-for-the-lhc/supersymmetry/supersymmetry-what-is-it/ . So a supersymmetric version of the Standard Model with all superpartners with masses at 10 or 100 TeV/c^2 would be a somewhat unnatural theory, but not nearly as unnatural as the Standard Model itself.

      2) The Michelson-Morley-era physicists didn’t know, at the time, what they’d found or not found. I think your way of saying things is only semantically different from mine. Similarly, we do not know what finding the Standard Model alone would mean. Only in retrospect will we know. I’m not suggesting that the LHC results and the Michelson-Morley experiments have anything specific in common. The only thing in common is that experts at the time didn’t know what they meant. Since the Michelson-Morley experiment revealed something completely beyond anyone’s thinking in 1887, something that showed up in experiments that were not even being thought about at the time, that’s a warning to us that our current thinking about what it would mean if the LHC finds only Standard Model phenomena might be highly misleading, and that we need to keep our eyes open. That’s all I’m saying.

  9. Markus Harder

    Maybe slightly off-topic, but it just came to my mind that there is another large experiment going on that has a “found nothing so far” situation. The search for extraterrestrial intelligence (SETI) looking for signs of intelligent signals in radio and other signals received from outside our solar system. The projects are now already running for decades, and so far no little green man sending out radio messages has been found. Only a very small fraction of the signals spectrum has been investigated so far, so it is still an open question if there will be a discovery (maybe already tomorrow), or if there are no other civilizations at all that emit radio messages (at least in the part of the universe that is accessible to our receivers). I think the search is necessary if we wish to know if there are other civilizations around, and at least one positive knowledge has been obtained by the observations so far: Now we know that at least that our cosmic neighborhood is not abundant with radio-messaging ETs.
    But a difference to the LHC is that the SETI projects receive few or no public funding, the SETI@home search is run on the spare computer time that many people voluntarily contribute. So this search does not block funding for other projects, it does not consume the general taxes. Therefore it is much easier to accept for the contributors that possibly the outcome will be nothing (while there is still the chance that some very interesting signal is just around the corner).

    • Some things intrinsically cost more than others. The really important searches for extra-terrestrial life are taking place via Kepler and other telescopes. Kepler cost 0.5 billion, not as big as a collider but not negligible. The Curiosity rover isn’t cheap either. Neither one was guaranteed to make huge discoveries. Society has to make choices about what it wants to know and the risks it’s willing to take with small outlays. Keep in mind that a 10 billion dollar machine built over 15 years costs each tax payer a few dollars a year… and most of that money pays for *people* — contractors who spend that money back in the U.S.

  10. 100 TeV collider is to generates enough juice to slosh the syrupy (luminiferous ether?) Higgs field around now and again, producing Higgs bosons – or to stop the momenta in the four vectors, three dimensional momenta plus the energy as the fourth component in the special metric of special relativity ?.
    The mass, in this framework (clumping) is the corresponding “length” of three dimensions and is called the “invariant mass”. Because “space condensate” = momentum + energy – clumping ?

  11. For a discussion about experiments that set limits on extra dimensions by trying to find corrections to Newton’s law, cf., for instance, http://www.diva-portal.org/smash/get/diva2:652635/FULLTEXT01.pdf

  12. kashyap vasavada

    Matt: This question is not about MM expt. on ether, but rather about a possible medium with respect to which absolute motion can be detected. Some people say that CMB is such a medium (or whatever you call it). Motion of earth (or solar system) with respect to CMB can be detected. Since it is electromagnetic wave, there is no question of detecting speed of light w.r.t it ! There would be a problem in talking about expansion of space also w.r.t.it. There is some catch in this argument. I would like to know how one can answer it.

    • The CMB (photons of the cosmic microwave background, which appear of constant temperature in a unique frame of reference) is not such a medium. Motion relative to the CMB can be detected, yes, but that’s just a statement that there is a CMB, nothing more. In other words, it’s a statement about what’s in the universe, not about how the universe’s laws work. Just because I’m in a tank of water, relative to which I can detect motion, doesn’t mean the universe’s laws care that there’s water in the tank. Light waves don’t care about the CMB. Their motion, relative to you and independent of how you are moving relative to the CMB, remains always the same.

      Said one more way: the existence of the CMB does not violate the principles of relativity.

      • The CMB doesn’t really single out a unique frame of reference either–it only does that if you’re using a coordinate system that treats widely separated galaxies as being “really” at rest with respect to each other while space expands between them.

        If OTOH you treat the mutual recession as “real” then the CMB doesn’t identify a single rest frame for the whole of space, rather it singles out a different “rest frame” at each point in space. Two observers at opposite edges of the observable universe, each “at rest” with the local CMB, would be nonetheless be moving away from each other at a substantial fraction of the speed of light.

  13. Michel Couture

    My brain has been asleep for a month or two, until I read this… Thanks Matt!

    I would say that Matt’s analogy to Ether experiments is more than just an analogy to me; it could be the same problem. Maybe there is no true vacuum energy and spacetime is quantized in all measurement aspects. Possible interesting researches are the many-body entanglement mechanisms, a holographic principle and a modified GR theory which would agree with Mach’s Principle (the true initial goal of Einstein). Gravity and electromagnetism are entirely reciprocal effects between two particles; therefore, there is no absolute event horizon. Spacetime may be quantized without any apparent space quantization. The Higgs is not a proof of vacuum energy.

    The problem with a 100 Tev accelerator is its high optional costs; meaning, if you put money and energy into something, you don’t have it for other things… if we could understand black holes…

    You don’t have to be old to be wise.

  14. Part of the nightmare scenario, is the possibility (as yet to be verified) that naturalness simply does NOT hold, that effective theory intuition does break down for some reason, and that the hierarchy problem becomes the hierarchy fact.

    The real problem with this, is that naturalness is the single biggest constraint on high energy model building that people can imagine. Once you allow for the possibility of an unnatural theory, the possible theories of nature grows geometrically.

    Its hard to really see how anyone can progress at that point. Ok, maybe we figure out dark matter and the electroweak sector through experiment for the next forty years, but we were very much hoping this regime would give us a clue about how to proceed at even higher energies. If that clue opens up a host of possibilities, as opposed to constraining them, then that is really the nightmare.

    • I agree, we were hoping for a clue, and we had good reason to expect one. Michelson and Morley were at a time where people expected detection of the ether to give them a clue also.

      And I agree it is really hard to see how to make progress. But it was hard then too. Most people made no progress at all. FitzGerald and Lorentz were very smart, and they didn’t find it easy. They wrote a number of papers, some of which were quite confused, and all of which were, in one way or another, not correct. Which is to say that most of us will make no progress thinking about this; a few of us will be clever enough to start off in new directions; and perhaps one of us will be both lucky and extremely smart, and stumble on the right idea, as Einstein did.

  15. Dear Matt,

    Didn’t mommy tell you never to mention the ether in company? Now look what you’ve done!

  16. When an electron has zero kinetic energy, it ceases to be an electron. The CMB has been in this phase (There is always a minimum kinetic energy). An electron that ceases to move won’t decay to some other particle.. because of the law of conservation of charge. An immobile electron, in temperature terms, be absolute zero. In a box, for example for an electron in the hydrogen atom in the ground state (about 0.1 nm diameter) the kinetic energy is about 1eV, which translates to 2.200 km/s.
    So stopping the momentum of an elementary particle will grind to halt the cog of momentum – which will backfire due to inertia ?

    • The vacuum expectation value (VEV or /O/), this nonzero value of vacuum energy, the gauge invariance or “Spacetime Condensate”, which occupy the “lowest-energy state (or quantum state)” – meaning “less movement more heavy”. So the mass-energy must be lighter than vacuum energy in thermodynamic equilibrium – this heaviness was the inherent property of the ultraviolet catastrophe,which led to planck constant.
      It works in condensed matter because of particle nature of both photons and fermions.Fermions are time-dependent but photons are time-independent, here comes the relativity ?
      The “lowest-energy state” has been maintained by moment of inertia (even massless particle must have photoelectric effect)!
      Moment of inertia can never be created, nor be destroyed.

      Spacetime described by a differentiable manifold is an emergent entity and the metric or connection forms are collective variables valid only at the low energy, long wavelength limit of such micro-theories.
      We cannot extrapolate condensed matter results to microscopic structure of spacetime until we stop the cog of momenta ?

      http://arxiv.org/abs/gr-qc/0503067

    • I would note that only ‘massless’ particles such as the photon cease to exist when they stop moving (Have no kinetic energy.) massy particles like the electron can indeed have zero kinetic energy and be perfectly fine.

      • Thank you Mr.Kudzu, nice to meet again.
        “Lowest-energy state” need momentum of inertia, does not mean, inertia is without movement. The group velocity of an electron and the uncertainty of the momentum in the Heisenberg’s principle is not the same as the velocity of a particle (relatively particle in reality wave).
        The group velocity of an electron can be zero. It is a standing wave in this case, your electron would have the wavelength infinity and would be delocalized across the entire universe.
        There is no spacetime, no relativity – the temperature will be below CMB. With absolute zero thus being, in fact, minus infinite, so that, say, -273.151 Kelvin cannot exist.
        There may be a chance to exist in much “lowest-energy state” more massive “Dark mater particle” ?

  17. laboussoleestmonpays

    Dear Julian, I think Matt was right to mention the classical ether for the purpose of his argumentation. He makes a nice and courageous work of popularization and takes some “risks”. Of course the “ether” word is like a magic, pandora box and triggers wild speculations but for a condensed matter physicist working with low energy excitations over different kinds of electronic quantum liquids this is not necesseraly a dirty world, just a “meme” so to speak (of course Fermi sea or fractional quantum Hall liquid are more politically correct or fancy…).
    To come back to the Higgs naturalness issue I think naively that it is interesting to notice that the “natural” solution for accelerator physicists is to look for new particles while the “natural” idea in a solid-state physics perspective is to think first about a new ether, a new vacuum state in order to make the scalar sector richer. Then its new phenomenology could be tricky to uncover with a collider but we can rely on astroparticle physics now since quantum cosmology has been born with Cobe, WMAP and Planck satellites.
    Last but not least I wonder if, before thinking about new particles or new quantum vacuum, one would rather not look for a better or more subtle spacetime model to embed the Standard Model and its Higgs sector in a more generic or “natural” framework.

  18. It’s interesting to note that, even though the LHC has just completed its first two years of running, hasn’t, yet, reached its design energy or luminosity-yet has, nonetheless, discovered the spin-0 particle that realizes the Brout-Englert-Higgs mechanism in the Standard Model, there is so much discussion about whether it might, could and so on discover “anything else”-which is, necessarily, a *metaphysical* discussion. Once more, let’s recall that the discovery of the decay of the Higgs to tau leptons was established, to 4 sigma just a few months ago-even though this process is part of the Standard Model, whose parameters are, now, known, some to high precision. The backgrounds generated by the LHC, or any collider at these energies, are exceedingly challenging. Learning to master them, to extract known events from up to 50 simultaneous collisions (the “pileup” projected to occur during the future runs) requires time and sustained effort that don’t mesh well with a 24/7 blog cycle that expects instant discoveries.
    So I don’t think that it makes much sense, at the present time, to make claims one way or another. What we should, rather, realize is the physics, e.g. that the potential of the scalar contains a parameter, the vacuum expectation value, whose scale is physical and whose ratio with other scales is the interesting issue. What one calls this issue isn’t interesting-recognizing that it is an issue is the point. How quantum corrections can affect it is something we should learn to describe.

  19. I note two apparently correct predictions of the Higgs boson mass from arXiv; the first, 0912.0208 linked to the neutrino minimal standard model, seems to have some connection with standard physics; the second 0912.5189 is linked to the four color theorem and seems to be from a different world; I do not understand either of them well enough to make a judgement about whether they are nonsense or of interest, wonder whether either could be the kind of insight you are asking for, and would value your comments at some point.

    • I just want to point out that predicting a single number to a certain rough approximation (and nothing else) does not impress us very much. Other theories predicted this number (to some approximation) also. So who’s right? We can’t decide until *other* predictions of these theories are tested… which shows you that predicting one number doesn’t buy you very much.

      Of course, if a theory predicted some very different number, then we can discard it.

      Unfortunately, many, many theories don’t predict the Higgs mass, anymore than planetary formation models predict the location of the Earth. That doesn’t make them wrong. So we have to consider all those theories too!

      • My reason for drawing attention to these two papers was not just their prediction of the Higgs Boson mass. Both are attempts at all encompassing theories which predict that we will find very little in addition to the standard model. The first, together with right handed neutrinos, is supposed to account for dark matter, inflation, and the baryon/ antibaryon asymmetry. The second supposedly explains everything on very general topological principles. The second seems to me extremely far fetched, the first seems very attractive – and I am not well qualified to assess either! Both seem to me to be an attempt to do what you were suggesting, as a way forward if the LHC detects nothing else except the standard model.

  20. So are you saying instead of spending billions on dollars on a new 100 TeV collider, it would be better to spend that money on theorists to help them figure out some reasonable solutions to the naturalness problem, and only then spend money to build the appropriate experiments.

    I wonder if throwing money at theorists would help ( hiring more, setting up theory schools, jetting them around to more conferences, bigger computers, big prizes ). I’m sure one could do a lot with a few billion :)

    • No, I didn’t say that … for one thing, only a small number of great theorists are likely to be able to change the situation, and even collectively, they’re not expensive.

      More money *should* be spent on theorists, but mainly on theorists who are helping dig information out of the LHC data. Because it would be terrible if, by underspending on these theorists, we fail to actually discover something that was sitting in the LHC data all along. Then we really could end up building the wrong accelerator.

      An exploratory 100 TeV collider (again, IF the LHC finds nothing else — for if it finds something, that changes everything) is still a step along a well-trodden and well-motivated path: exploring the universe’s laws at shorter distances. It may be the machine we need, because this path may be the best path. It’s expensive, but it’s also uniquely suited for a step toward shorter distances.

      But while we’re thinking about it, planning for it, and building the Higgs factory that will go into the same tunnel, we should also be exploring as many other conceptual and experimental directions as we can. Perhaps one of them will unlock a secret before we even start building that 100 TeV machine.

      • /A 100 TeV collider would make a Higgs boson many times per second./–
        Standard Model Higgs bosons ? What is the use of more quantity ?
        If the Higgs particle of more “lowest-energy state (more massive)” below the temperature 2.725 Kelvin of Cosmic microwave background radiation, not found – the cog of momenta would not be disturbed.
        The 100 Tev cannot explore the universe’s laws at “much” shorter distances – and find supersymmetry and dark matter particles, beyond SM ?

        • If there is something that Higgs bosons rarely do, then you will not observe one doing it unless you make a large quantity of them. We make as large quantities of we can of all the particles we poorly understand, because that’s how we learn about their behavior.

      • “only a small number of great theorists are likely to be able to change the situation, and even collectively, they’re not expensive.”

        This might be a dangerous reason to cut funding for “fundamental” theorists. Surely we need only a few of those, right? Unfortunately, we only know when such a theorist is great until they make their great discovery. Often this happens when they are well in their 30′s.

        Plus, there’s the problem of noisy recruitment; those people getting tenure may be always be the best.

        In my opinion, more theorists would render more great theorists.

  21. Forget about physics a little while and enjoy an amasing version of Billy Hollidays “Gloomy Sunday”, sung by a 7 year old girl :-)

  22. “… the Standard Model isn’t all there is to physics.” Are there any other challenges to the empirical validity of the space roar besides the following?
    http://arxiv.org/abs/1305.7060 “Is there an unaccounted excess Extragalactic Cosmic Radio Background?” by Subrahmanyan and Cowsik

  23. Here briefly is a different perspective on the universe.

    E=Mc2 says that everything is energy. Like god it’s everywhere and everything while remaining a mystery.

    And as everything is energy energy is all there is. If energy is all there is perhaps it is all that ever is, that ever was and ever will be. That which just is, always.

    Now, we say there are four fundamental forces but all those forces have to do with attractive and repulsive forces. So, let’s say there are really only two fundamental forces, attraction and repulsion.

    Now, we know that everything is energy but we do not know what energy itself actually is. In order to be energy, however, it must be energetic. If energy is all there is, then, its energetic activity must be self-generated. That energetic activity could be the result of an inherent attraction/repulsion dynamic A/R. That is, energy is attracted to itself while at the same time repelled by itself. And a particular manifestation of this energy was the progenitor of the so-called big bang.

    The idea of time is associated with this energetic transfer. Time seen as the transfer of energy from one state to another. Which is basically what time is.

    There would be an infinite variety of states in this energy as the ratio of attractive energy to repulsive energy would always be in flux. Among those states, however, there would be one where A/R would be in perfect equilibrium and energy would cancel itself out. And that would be its eternal state. As far as eternity is concerned nothing exists. Eternity cannot be arrived at. It always is, always was, always will be and doesn’t change. Within that eternity, however, all manner of various configurations of A/R are possible. Eternity would, in effect, comprise all possible states including, of course, the one where A/R is perfectly equal. The equal state where energy cancels itself out is the actual eternal state because it is the only one that never changes. Any particular temporal manifestation of energy is nonexistent as far as the eternal is concerned.

    Think of the attractive force as negative and the repulsive force as positive and relate them to negative and positive numbers. There are always as many negative numbers as positive numbers and, therefore, the numbers cancel themselves out leaving only zero, or nothing, forever in their stead. But the numbers still persist.

    It’s also like the classic world in relation to the quantum world. as far as the QW is concerned the CW doesn’t exist. Yet, here we are.

    Prior to the big bang, then, every point of the one energy was continually attracted to and repelled by itself simultaneously, causing minuscule energetic vibrations that kept a virtually infinite energy in check. So, the attractive/repulsive points were very close together and the enormous energy of the whole was contained by the constant and minuscule energetic transfer from attraction to repulsion and vice versa. A little glitch at any one point, however, could unleash a massive amount of energy. And such was the beginning of our universe.

    Initially, the decoupling of A/R resulted in the repulsive force going off on its own while the scattered attractive force was swept along and huddled together as best it could. There was no radiation yet released in this initial state and, therefore, undetectable. This accounts for the macrocosm wherein the microcosm could come about.

    The initial decoupling of A/R pealed the energy open, as it were, and made possible the release of radiant energy that we know as the big bang. Light is a direct manifestation of the coupling of the A/R in energy itself as it is composed of the forces of attraction and repulsion and is in a sense attracted and repelled by itself.

    From the forces of A/R we can derive characteristics of the universe that seem to stand in opposition to one another. In terms of energy itself they can be seen as absolutes and our universe exists by virtue of a dialogue between them.
    absolute unity absolute diversity
    absolute uniformity absolute disparity
    absolute stability absolute instability
    absolute order absolute chaos
    absolute contraction absolute expansion
    absolute constancy absolute change
    absolute attraction absolute repulsion

    The absolutes that make up each column are interchangeable with one another. Unity, uniformity, stability, order, contraction, constancy, attraction are all intimately related to one another as their opposites are to one another. The one common denominator in all of these absolute pairings is attraction/repulsion because they qualify as forces; forces whose cooperative contention all of the other dualities can be seen to be an effect of.

    Think of a black hole in terms of the column on the left side and dark energy in terms of the right side.
    In terms of time gravity can be seen as a retreat to the past, an attempt to return to energy’s primal state while dark energy proceeds apace into an empty future and galaxies are islands of time that persist in between.

    The forces of attraction and repulsion factor into every phenomenon of the universe including life itself. The folding of proteins is due to the attraction and repulsion of amino acids with respect to the alignment of their specific charges and also to hydrophobia, the repulsion to water, by the non-polar amino acids.

    A/R is also manifested in the behavior of organisms. Primitive one-celled creatures swimming in primordial tidal pools functioned by employing such a dynamic. They were attracted to food and repelled by toxins. Here we have the beginnings of conscious intelligence where informed choices are made. In the case of more evolved animals the interplay of attraction/repulsion becomes more complex. For instance, a female cheetah with cubs is faced with a dilemma. For days she has been staying close to her cubs to protect them from lurking predators. But her growing hunger is telling her its time to hunt before she becomes to weak. The thought of food is attractive. The thought of protecting her cubs is also attractive. The thought of leaving her cubs alone is repulsive. The thought of becoming weak with hunger is also repulsive. She is reluctant to leave her cubs but she knows she has to. Her cubs might be okay on their own for a while but without food neither they nor she could survive. And so, finally, her attraction to food becoming too strong to resist, off she goes to hunt. Further along the evolutionary track we have human beings who can reflect about what they are attracted to and repelled by and can philosophize about it in grand style.

    In this way we can feel ourselves to be thoroughly embedded in the fabric of the universe rather than somehow estranged from it. This not to say our existence is inevitable and necessary. No, the universe is under no obligation to produce creatures such as ourselves. The universe would exist regardless of whether we materialized or not. But the universe would not be what it is without the possibility of our existence. In that sense we are intrinsic to its existence.

    • You may find it useful to consult a dictionary re the meaning of “briefly.”

    • A few brief comments.

      * E=mc^2 says mass and energy are *equivalent*; it is as valid to say all things are mass as it is to say all things are energy. Like water and ice they are different forms of the same thing.

      * Just because two effects of forces are attraction and repulsion does not follow that these are the only two components of said forces. You could equally say that there are just six directions (Left\right, up\down frontwards\backwards; the only six ways any force can move anything) or just one, speed (something will move identically if attracted OR repulsed.) To say there are only two forces we would need some theory of combining those two components to produce everything we see in the way electron shells (with a few other things) arrange electrons to give us chemistry.

      * What energy (or matter!) ‘is’ can never be ultimately answered; you can always ask ‘But what IS that?’ in the same way you can always ask ‘But why?’

      * What is ‘energetic activity’? and what is ‘self generated’? I think you are saying that if there is only one basic kind of thing making up everything then logically it does everything which is a bit of a tautomer. I also think you’re saying the universe is eternal since you speak of something ‘before’ the big bang.

      * Time is not just energy transfer; it is possible to have a closed system where energy is constantly being shuffled between a number of states (Such as a glass of water where the molecules are constantly swapping kinetic energy and even splitting apart and reforming.) which, by itself has no net arrow of time. If time is associated with anything it is the increase of entropy, disorder. The turning of ‘useful’ energy into ‘useless’ energy.

      * Flux does not create an infinite number of states; watching the same movie over and over keeps the movie screen in a state of flux but does not mean you will see an infinite number of unique movies. To do that you would need an infinitely large screen that changed in a random manner.

      * There are many eternal states that are ‘unbalanced’ in various ways. A universe consisting of a single electron has no attractive or repulsive forces and is eternal as is an empty universe. A universe of two electrons has largely repulsive forces but is also eternal (Though the distance between the electrons changes, without anything else to measure that distance distance really has no meaning.)

      * Negative and positive numbers do not ‘cancel’; or balance. The number line is a way of organizing numbers but there is no fixed number of them. I can have as many 2s as I want for edxample without having to balance them with -2s.

      * As far as I am aware the force between two photons is only attractive (gravitational via their energy) and it is possible to fit as many of them as you wish as close together as you want (Until you get a black hole in some situations.)

      * I do not understand your absolutes; for example we see change but not everything changes (so it can’t be absolute) unless we count the universe as a whole as one object in which case it changes and there is no absolute constancy. What is ‘absolute instability’? would that be something that is totally unstable and so never exists, or is it that nothing is truly stable or something else?

      * Again your division of things into attraction vs repulsion is a nice bit of philosophy but I fail to see what is so special about it. Again I could explain everything in terms of the six directions of motion or love vs hate or good vs bad. It also fails to explain inactivity;many things in the universe do nothing, neither attracted nor repelled, are inert. Things sleep, hibernate, freeze.

      Those are my thoughts.

      • I strongly disagree with some of these statements, ESPECIALLY the statement that energy and mass are basically the same thing, which is the statement that E=mc^2 ALWAYS. That is only true with the definition of mass that particle physicists, for very good reasons, do not use. With your definition of mass, photons have a mass. With particle physicists’ definition, photons are massless. Einstein used both definitions of mass; this is the source of the confusion. http://profmattstrassler.com/articles-and-posts/particle-physics-basics/mass-energy-matter-etc/more-on-mass/the-two-definitions-of-mass-and-why-i-use-only-one/ On this website, mass ALWAYS means what people generally call “rest mass”, and this is NOT the same as energy.

        • /On this website, mass ALWAYS means what people generally call “rest mass”, and this is NOT the same as energy./
          Energy and momentum is mass. There is no “rest mass” here. Due to uncertainty principle, there is “no” zero movement. The “inertia” appears as “invariant mass” here.
          We can increase the kinetic energy of a charge accelerating across a potential difference, does means, the charge already have an inertia.

          The “lowest-energy state” photons (ground state) could be shared by other gauge invariance (or Spacetime Condensate) – means, it is not bond by this inertia. The cosmological constant simply allow its increase of entropy.
          But the gauge invariance’s symmetry is broken due to the non-zero value of CMB (at present) – making a non repeating pattern of “Spacetime Condensate” at different “time” – due to creation of new space or expansion of space or non-zero cosmological constant (rather than increase in entropy).
          This makes the “lowest-energy state” of electrons “cannot” be shared by other space (time?) condenstate. Which is bond to “inertia” and makes this inertia as “rest mass” ?

      • * E=mc^2 says mass and energy are *equivalent*; it is as valid to say all things are mass as it is to say all things are energy. Like water and ice they are different forms of the same thing.

        you can split an atom to produce energy can energy be split to make an atrom?

        * What energy (or matter!) ‘is’ can never be ultimately answered; you can always ask ‘But what IS that?’ in the same way you can always ask ‘But why?’

        I don’t know what energy is

        I also think you’re saying the universe is eternal since you speak of something ‘before’ the big bang.

        no, did not say universe is eternal

        * Time is not just energy transfer; it is possible to have a closed system where energy is constantly being shuffled between a number of states (Such as a glass of water where the molecules are constantly swapping kinetic energy and even splitting apart and reforming.) which, by itself has no net arrow of time.

        your “splitting apart” and “reforming” are separate instances and are marking time, at one moment splitting apart, next moment reforming

        * Flux does not create an infinite number of states; watching the same movie over and over keeps the movie screen in a state of flux but does not mean you will see an infinite number of unique movies. To do that you would need an infinitely large screen that changed in a random manner.

        same movie is not random flux just repetition of same patterns

        * Negative and positive numbers do not ‘cancel’ or balance. The number line is a way of organizing numbers but there is no fixed number of them. I can have as many 2s as I want for edxample without having to balance them with -2s.

        ok, and i can have as many 2s as i want with as many -2s

        • You are deeply confused; I can see this conversation will get you (and other readers) nowhere. Pick one subject at a time and understand it thoroughly; then move to the next subject. Otherwise you’ll just create a huge number of confusions layered on top of each other — and what good will that do you?

      • i have some time now to elaborate a bit re one of your comments

        “I also think you’re saying the universe is eternal since you speak of something ‘before’ the big bang”

        no I did not say universe is eternal

        for the singularity of a black hole space becomes time, its singularity is time, revealing that gravity is a form of time, it is a time with one direction, namely, toward the past, a black hole takes stars out of the time they existed in and brings them back to what they were before they existed

        the direction of dark energy is outward toward the future, it creates the space for things to happen

        galaxies will collide with one another and form bigger and bigger black holes, imagine a black hole the size of our galaxy, imagine the merger of a number of galactic black holes powerful enough to eventually suck up all the dark energy and thus reinstating energy as it was prior to big bang eruption

        • absolute unity absolute diversity
          absolute uniformity absolute disparity
          absolute stability absolute instability
          absolute order absolute chaos
          absolute contraction absolute expansion
          absolute constancy absolute change
          absolute attraction absolute repulsion

          * I do not understand your absolutes; for example we see change but not everything changes (so it can’t be absolute) unless we count the universe as a whole as one object in which case it changes and there is no absolute constancy. What is ‘absolute instability’? would that be something that is totally unstable and so never exists, or is it that nothing is truly stable or something else?

          Absolutes? Absolutely. Think of the universe as existing between the forces of attraction and dark repulsion. A black hole is absolute attraction to which the rest of the left hand column conforms to. Dark energy is absolute repulsion in that there seems to be no end to its pushing things apart or to its relentless expansion. The right hand column all relates to dark energy.

          Galaxies exist between the two absolutes. But the two forces are not friends of galaxies, which we all know are anomalies in the universe, with black holes eating galactic matter and dark energy pushing them around and would, if galaxies were vulnerable, take them apart.

          What keeps the dark energy from invading a galaxy is its halo. Which seems to me to be comprised by a standoff between dark energy and gravity along the dark mater trapped there.

          It’s all about attraction and repulsion. They are fundamental to the posited fundamental forces of the standard model. And dark energy needs to be seen as a fundamental force.

  24. Pingback: Waarom is de zwaartekracht zo ontzettend zwak? | Astroblogs

  25. Another great post, thank you.

    Could you please comment more on your statement that you don’t think the LHC will directly observe dark matter or dark energy?

    • We have zero reason to think that proton-proton collisions can cause any effect on, or be affected by, dark energy.

      If dark matter is made from particles of of certain particular types, proton-proton collisions can directly or indirectly cause dark matter particles to be produced, and so it is possible, in that case, for dark matter to be observed by the LHC (as undetected objects recoiling against detected ones.) However, if dark matter is made from particles of other types, or isn’t made from particles at all, then the LHC won’t make any of them. So there’s a possibility, but no guarantee.

  26. FWIW, one of the best justifications for a 100 TeV collider, in a null scenario at LHC, I think, is to test the Standard Model beta functions, i.e. how the coupling constants of the three fundamental forces and the properties of the known particles “run” with the energy scale of the interaction. This is something which the LHC can barely glimpse, while a 100 TeV collider could establish definitively to much higher energy scales.

    This matters because the form of the beta function is one of the most powerful means of discriminating between SUSY theories (in the part of the parameter space with detectable superpartner particles that are too heavy to be directly detected even at a new collider), and the Standard Model. SUSY theories generically have much different beta functions that make “gauge coupling unification” (at which the three Standard Model force gauge coupling constants take identical values at the same energy in a “grand unification” of the three forces) possible. The Standard Model beta functions do not lead to gauge coupling unification, and the distinction between the two, while fuzzy at the LHC even at its highest energies, ought to be “right around the corner” at a 100 TeV collider. If none of the beta functions of the gauge coupling constants of the Standard Model bends materially away from the Standard Model predicted value in a 100 TeV collider, then SUSY theories are in much deeper trouble than mere non-detection of superpartners would imply.

    Still, I don’t think one has to puzzle too hard to think of other ways to spend money that could have gone to a 100 TeV collider. For the foreseeable future, astronomy observations, ideally with deep space observatories in novel wavelengths, are going to be more useful in pinning down dark matter and dark energy which we know that we don’t know enough about, than colliders. The immediate future for neutrino physics likewise has lots of known unknowns and a clear agenda for bridging the gaps. Greater computational power for QCD research is a sure win, because we know already what equations we need to calculate the answers to more precisely and how, but simply don’t have enough raw computational power to do it.

    Some of the other very interesting experiments also involve creating exotic atom-like structures, e.g. postitronium that substitutes a positron for a proton in an atom-like structure, or muonic helium that substitutes muons for electrons in a helium atom. Those aren’t cheap, but just about everything is cheaper than a 100 TeV collider.

  27. Magnificent essay, wonderfully philosophical, or just how future science is guessed by exploring how we established our beliefs..

    Let me roll out my prime obsession, as a suggestion for a breakthrough: doing the delayed 2 slit experiments at ever increasing speeds. Such a set-up forces a particle (say a photon) to switch from wave to particle by introducing a beam splitter (or not). (The idea was published by Wheeler and Al. in 1978, although Popper, Einstein, and colleagues may have been aware of it much earlier.)

    Such an experiment was done recently (2013) and confirmed that particles are neither really waves nor particles. As Ma, Zeilinger and Al. put it:
    “…the system photon behaves either definitely as a wave or definitely as a particle would require faster-than-light communication. Because this would be in strong tension with the special theory of relativity, we believe that such a viewpoint should be given up entirely.”

    Belief is good, but facts are better. There, in the ultimate behavior of particles, or waves, or whatever they are, is the ultimate tension with all theories of space, time, energy, momentum, subjacent below today’s physics. Instead of just exploring ever higher energies, one should try to explore faster and faster beam splitting, in the hope of cutting into pieces that portable ether, Michelson-Morley seem to have found.

    Those attempts to cut the photon may be enlightening about the nature of Dark Matter and Dark Energy too, as smaller time scales mathematically correspond to the enormous distances at which it is not clear that the gravitation law holds (as, on the face of it, it seems to somewhat fail outside of the solar system!)

  28. Some of the comments I’m reading these last two posts are pissing me off… I will paraphrase…

    1) ‘Tell me what is over the next horizon and then I’ll consider funding your 100 TeV collider.’ Think people – if we knew what was over the next horizon, we wouldn’t have to go to the trouble of building the next machine to find out now would we. If this is the reaction of people who love physics I can only imagine what physicists have to go through to convince our wonderful broad-minded politicians.
    2) ‘Why stop at 100 TeV, why not 200 TeV or 500 TeV?’ I would indeed suggest a higher energy machine if I thought you people would support it. Eventually we will of course have such machines, they will pack much more of a punch per unit length than the LHC, but will not come on line until mid-century.
    3) ‘It’s like SETI, except SETI doesn’t take public funds.’ It’s not like SETI. Most of you (maybe all of you) don’t realize it but SETI is extremely arrogant and narrow minded – assuming as it does that civilizations with a million years on us – are using light speed radio waves to communicate.
    ‘Well of course, what else would they be using?’ Pretty cocky from people with only 4 centuries of science in your pocket. I will take your assessment of what is possible and impossible in this universe more seriously when you have 4000 centuries of science in your pocket.

    The whole philosophical approach of a 100 TeV collider is far more humble – we don’t know what’s out there but we would like to find out.

    Matt, I’m not really taken with your drawing an analogy between the MM experiment and the LHC. The MM experiment did NOT find what was expected; namely motion relative to the ether. The LHC HAS found what was expected; namely the Higgs. IF the Higgs had not been found your analogy would be much better one. I know… you are drawing analogy to other things beyond the Higgs that have not been found. But other than a small minority of physicists no one counted on anything beyond the Higgs. The Higgs is the elephant in the room!

  29. ScentOfViolets

    Matt makes a comment above about the relative costs of telescopy. Let me add to the list of relatively cheap things to do: (advanced) LIGO and LISA. I’m not expecting otherwise, but . . . what if no gravitational waves are detected by what seems to be a perfectly straightforward setup? And what would that say about plausible extensions to the SM?

  30. ScentOfViolets: Gravitational waves are an obvious consequence of gravitation as a field propagating at a finite speed. It’s not imaginable they don’t exist. One more reason to check they are there, agreed!

    • The intended measurement of gravitational waves is not only for confirming that they exist. Gravitational waves, if they exist and can be observed, are another way to look at objects and processes that are otherwise difficult (or impossible) to observe. For example, to look “behind” the cosmic microwave background. Or possibly as a means to observe effects involving dark matter or black holes. But also more common things like supernovae. Many interesting things to “see” if we had “eyes” for gravitational waves. The experiments LIGO and LISA will not yet provide detailed imaging of gravitational waves, but would provide an important step forward towards exploring the universe in an so-far unexplored way.

  31. “Experts: As I emphasized in my Santa Barbara talk last week, appealing to anthropic arguments about the hierarchy between gravity and the other forces does not allow you to escape from the naturalness problem.”

    I’m no expert, but I saw the now posted seminar (and some of the others) with great interest. I get that anthropic models can’t solve naturalness I think.

    But what I don’t get is why there is an implied requirement for theories to be panaceas. This was the idea that there could be a unique theory that worked and then decided all parameters, a “theory of everything”. Now we hear that anthropic theory wouldn’t predict the Higgs mass (IIRC).

    Well and good, perhaps another theory predicts that. But it wouldn’t necessarily have to predict more. (Or we are back to the TOE requirement again.) Isn’t “divide and conquer” a good strategy, if it works?

  32. Pingback: Philosophia Naturalis I | Patrice Ayme's Thoughts

  33. “… Extremely unnatural systems — that is, physical systems described by quantum field theories that are highly non-generic — simply have not previously turned up in nature… which is just as we would expect from our theoretical understanding. …”

    I am sorry to ask, but could you clarify what the expectation was? I can read that sentence one way or the other… Was the expectation that unnatural systems would turn up? Or that unnatural systems would not turn up, that we would have found only “natural” systems?

    I expect this means the later, but am not quite sure. For someone more versed in these matters, the way to read that sentence is probably clear, but at that point in reading this article I struggled already to understand what “natural” and “non-generic” mean in that specific context… Oh well. :-)

    And I am deeply sorry that I don’t have more time to read more of your work, because then probably such “pedestrian” layman questions by me would probably not arise in the first place! :-)

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