Visions of Future Physics

There’s a great profile of Nima Arkani-Hamed by Natalie Wolchover just out at Quanta magazine, under the title Visions of Future Physics. I recently linked to another profile of him from the IAS, which covers some similar ground.

He’s often been a topic of postings here, and the profile explains why, with his colleagues describing him as the “messiah”, “Pied Piper” and “impresario” of high energy physics.

“He keeps coming up with the goods, and his persuasiveness is hypnotic,” said Raman Sundrum, a theoretical physicist at the University of Maryland in College Park, “so a lot of people follow where he leads.”

I’ve often marveled at his performances, with his talks sometimes a unique mixture of brilliance, insight, and over-the-top outrageous indefensible claims (his talk here last week was uncharacteristically restrained). As an example of the genre, the IAS profile includes:

“It is extremely interesting to think about getting sophomores up to the speed of a second-year graduate student. I think it is possible,” says Arkani- Hamed.

which is simultaneously quite inspirational and, well, nuts.

A couple years ago I was struck by a talk of his in which he showed a lot of self-knowledge, describing himself as an “ideolog” (see here). There’s more about this in the Quanta profile:

“It’s important for me while I’m working on something to be very ideological about it. And then, of course, it’s also important after you are done to forget the ideology and move on to another one.”

The ideologies on display this time include a very speculative picture of a future union of mathematics and theoretical physics:

Ultimately, he said, anywhere from 10 to 500 years from now, the amplituhedron and these cosmological patterns will merge and become part of a single, spectacular mathematical structure that describes the entire past, present and future of everything “in some timeless, autonomous way.”…

There is a mathematical proof, Arkani-Hamed observed, that all algebraic numbers can be derived from configurations of a finite whole number of intersecting points and lines. And with that, he expressed a final conjecture, at the end of a long, cerebral day, before everyone else went home to bed and Arkani-Hamed headed to the airport: Everything — irrational numbers, along with particle interactions and the correlations between stars — ultimately arises from possible combinatorial arrangements of whole numbers: 1, 2, 3 and so on. They exist, he said, and so must everything else.

Personally, I don’t think this is going to work out, but he’s right that people need a vision to pursue, to drive them forward in finding new things. Unless he gets a lot further with it, I don’t think this one is going to get so much interest as to drive out other ideas, especially from mathematicians interested in physics, who have other competing visions.

Where Arkani-Hamed has become a really problematic ideolog, one endangering the health of the subject, is in his insistence on “naturalness” as the central question of HEP theory at the TeV scale, coupled with the ideology that if the LHC doesn’t see new “natural” physics at the TeV scale, then the intellectual suicide of the multiverse is all HEP theory has to look forward to. He’s been pushing this ideology, hard, for quite a while now, and I think it’s long past time for him to take his own advice and “forget the ideology and move on to another one.”

Much of the article is about his efforts to push forward a Chinese plan to build a next-generation collider. Perhaps his great enthusiasm will help move this project along (a book about it by Yau and Nadis, From the Great Wall to the Great Collider, will soon come out). It raises all sorts of difficult issues for the future of experimental HEP, including that of the future of CERN, issues that will play out over many years (timelines for things like this are generally wildly over-optimistic, and here people are talking about 2042). Framing the case for a 100 TeV machine as “1% fine-tuning evidence for the multiverse from the LHC wasn’t convincing, even though we said it would be, so we need a bigger machine to get .1% fine-tuning evidence” is something that I think isn’t going to fly, no matter how enthusiastically presented. In the article Kyle Cranmer makes the point that .1% tuning versus 1% tuning means little:

“I am very sympathetic to the idea that this is a critical point in the field and that naturalness/fine-tuning is a deep issue,” he wrote in an email. “However, I’m not convinced that if we built a 100-TeV collider and saw nothing that it would be conclusive evidence that nature is fine-tuned.” There would remain the nagging possibility that a natural completion of the Standard Model exists that a collider simply can’t access.

and Jester

argues that if no new particles are found at 100 TeV, this will leave physicists exactly where they are now in their search for a more complete theory of nature — clueless.

I think David Gross has it right:

Gross, who considers naturalness a murky concept, simply wants a last-ditch search for new physics. “We need more hints from nature,” he said. “She’s got to tell us where to go.”

The case for mankind to embark on a new project to push forward the boundaries of science is the same as it has always been: even though it’s expensive and difficult, we should do it because we’ll see how the world works at an even smaller distance scale. Just possibly we’ll learn enough to understand how to improve the Standard Model and achieve an even deeper insight into the physical universe.

: Gross and Witten have an editorial today in the Wall Street Journal (as usual with the WSJ, try Googling the article to get around their paywall), supporting the idea of a Chinese Great Collider project.

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49 Responses to Visions of Future Physics

  1. Magnema says:

    I mean, technically, last year I was a sophomore and was taking a class that was typical of a second-year math grad student at my institution (namely, manifolds). It was difficult (although a part of that is because I’m more of a physics person than a math person), and I was an unusual case to boot. However, with more background support structure, I would think it intellectually plausible on behalf of (smart) students, albeit that the investment into education is likely larger than what the general population is willing to commit…

  2. Peter Woit says:

    As a sophomore in college I also took a second-year level graduate course (quantum field theory). Then, and even more so now, I’d describe the suggestion that I (or any other similarly ambitious undergraduate) was operating at the level of a typical second year Harvard grad student as, well, nuts.

    To be honest, I have no idea what Arkani-Hamed is actually talking about here. Presumably he has some more specific idea in mind about certain skills needed in a 100 TeV collider project, but I have no idea what they are. I do strongly suspect though that, whatever it is he has in mind, inspirational as well as delusional likely is an accurate way of characterizing it.

  3. Peter Woit says:

    And, by the way, I don’t think he’d necessarily disagree. “Inspirational and delusional” characterizes what it is to be an ideolog (at least a good one), and he’s well aware that’s part of his nature.

  4. chris says:

    I’ve had a sophomore in the QFT class I was teaching last year and I can confirm that it is nuts. What I fear Arkani-Hamed is going for is a “physics” education that skips the actual physics and goes right for the stringy multiverse thing. Classical mechanics and wave guide exercises in E+M are for the old generation and totally useless – we start with an arbitrary dimensional supersymmetric membrane…

    Also, I find the political lobbying for the next hadron collider immoral. Come on, we all know that the chances of a factor 5-10 in energy getting us anywhere are slim. That’s what a skeptical look at the current situation tells us. Should we sink billions into an almost hopeless endeavor for political reasons or rather pause a moment and use that money for finding other ways of accessing much larger energy scales?

  5. Bee says:

    It’s like watching a public case study on chronic caffeine overdose 😉

  6. srp says:

    There is another moral and practical issue for the collider project. China is an unfree country that is unfortunately becoming less free in recent months as Xi imposes his new security law (that makes science, culture, and journalism emphatically security concerns–basically everything is security) and cracks down on Western ideas (to the extent of trying to get rid of foreign textbooks in universities, etc.). Moreover, there is evidence that the Party is very concerned about long-term stability and its ability to keep control over society. A long-term transfer of the center of gravity of particle physics into such an environment does not seem wise to me. This project isn’t like putting on an Olympics, where journalists mostly have to be contained for just a couple of weeks.

    One could, of course, argue that swarming the country with cosmopolitan international physicists would exert a salutary influence on the political/cultural situation. To me the downside risk seems more compelling than the upside opportunity but I’d be happy to be convinced otherwise.

  7. Michael Hutchings says:

    As a naive outsider, I would think that a machine with 10 times the energy of previous machines would have a good chance of seeing something new. I don’t know why chris writes that the chances are slim. But the enormous resources that this would require are probably better spent on something else.

  8. Frank Quednau says:

    “There is a mathematical proof, Arkani-Hamed observed, that all algebraic numbers can be derived from configurations of a finite whole number of intersecting points and lines”

    May I ask what this refers to and how I can find more information about it?

  9. Scott Church says:

    It’s only a hunch… who can say…? But unless I’m missing something it seems to me that while increasing collider energies of 100 Tev or more may reveal some new physics, as things stand today vis ‘a vis the SM and/or M-theory we have no real reason to expect any until we can probe at something on the order of the Planck scale. That will require either radically new detector technology (and I mean radically as in unlike anything we can currently conceive)… or a collider roughly the diameter of the solar system (with all the attendant luminosity and detection issues overcome). Anyone care to speculate how we’re going to get that funded and built? 😉

    And if not… are the billions we’re liable to spend trying to bridge the intervening gap really anything more than a Hail Mary? It seems to me we need some new ideas… New ideas.

  10. John says:

    Isn’t being an ideologue about the same as being a true believer? You position is not swayed by facts but instead you search and cherry pick results you like to support your position. To me this is the exact opposite of what a scientist is defined as.

  11. Jan Reimers says:

    Can someone comment on calculating backgrounds between 10 and 100TeV. In particular
    1) Is the data useless if we can’t calculate the standard model background between 10-100TeV?
    2) Can we reasonably expect to calculate the high particle count (i.e. 2 in –> N out diagrams where N>6) cross sections given that the Black Hat team came to rescue with 2->4, 2->5 gluon cross sections at the last minute before the LHC started.
    3) Or am I miss-understanding the history?


  12. M says:

    «Whatever the answers are, here’s one monkey that’s going to keep on climbing, and looking around him to see what he can see, as long as the tree holds out». 99.9% of the world annual GDP is a byproduct of scientific progress, and a 100 TeV collider costs only 0.01% of it

  13. Peter Woit says:

    Michael Hutchings,
    The 100 TeV collider proposal is different than the LHC in the sense that with the LHC we knew that it had to see the Higgs or something even more interesting. There’s no similar argument for the next order of magnitude in energy. So the case for the next jump is harder to make. I think though the case can be made, the fact that the LHC case was a slam-dunk and this one isn’t shouldn’t matter.

    If we do go to 100 TeV, maybe we’ll see what the SM predicts, maybe we’ll see something new and unexpected. The only way to find out is to look, and I think it would be a shame if humans decided it wasn’t worth looking, better to spend the money on some aircraft carriers. You could reasonably argue that we should save the money, and theorists can try and figure it out by pure thought. So far, trying to get beyond the SM by pure thought hasn’t worked out well.

    The standard arguments about this are usually I think very naive, with those in favor saying “better than weaponry” (like my argument above…), those against saying “cure cancer instead” (or, essentially, “spend the money on me and what I do”). One thing to keep in mind is that while this is a very expensive project, it’s also one with a very long time scale, so the budget needed per year may not be out of scale with what is already being spent. We’re talking about modest spending shifts on the scale of budgets like the US,EU, China. It’s not at all clear what would get crowded out by a Chinese decision to devote part of its economy to a big project like this, instead of what people would otherwise be doing. Fewer aircraft carriers is a real possibility…

    I think Arkani-Hamed is making the case that you need to be a true believer to devote your life to this kind of work. There’s something to that, but it becomes problematic if you go beyond convincing yourself to keep going on a project that may not be working, and start convincing other people that something is working when it really isn’t. The question of when and how you decide to admit that something doesn’t work and move on is a huge problem for HEP theory now, and I don’t think he’s addressing that one, even while he acknowledges that you have to do this at some point.

    Jan Reimers,
    I assume that those kinds of questions are just what Arkani-Hamed’s Chinese institute is supposed to be addressing. As mentioned above, the time scale for such a machine is very long, lots of time for improvements in background calculations. Especially with all those sophomores doing the work of graduate students…

  14. Michael Hutchings says:

    I don’t know what the budget is like for the 100 TeV machine; the book should be interesting. Anyway I would hope that we could build it sometime, and probe as far as we can, since it is our nature to do so. My argument against building it for now, call this naive if you will, is that we have some urgent problems to solve in order to ensure the long term survival of human civilization, and the latter seems to be a prerequisite for really big science projects. For example, there is a lot of activity in China to develop “green”, “sustainable” technologies (out of acute necessity), and this is something that might get crowded out.

  15. paddy says:

    At the risk of sounding like a Philistine: When does advocating for a 100 Tev collider become also a “spend the money on me and what I do”?

  16. Daniel Tung says:

    “Personally, I don’t think this is going to work out…”
    May I know why?

  17. Yatima says:

    When does advocating for a 100 TeV collider become also a “spend the money on me and what I do”?

    When it becomes a private venture? “Shut up and take my dollars” applies. Of course, one can still apply for subsidies at L’Etat providence.

    But I would like to see a muon collider and the International Linear Collider first.

  18. Radioactive says:

    We should build a collider orbiting the earth if it would add a tenth of a percent to the sum of human knowledge. Worrying about budgets is for accountants. I could give a damn what is politically feasible at any given moment as long as it’s physically feasible.

  19. chris says:

    Michael Hutchings,

    it is essentially as Peter explained: there is no “slam-dunk” case for anything popping up below the GUT or Planck scales, which are at least a further factor 10^10 away. Note that Peter, contrary to all that his string theory enemies say, is a real “optimist” here. A “pessimist”, like myself, sees the standard model as a complete theory up to essentially the GUT scale, because all current evidence (GUT scale, right handed neutrino scale, instability scale of the Higgs potential and Planck scale) points at that.

    It’s a good question what conclusion to draw from this. As Peter pointed out, it is very unlikely that money not spend on a future hadron collider will be used in any more sensible way. And while we might not find new physics, the simple benefit of keeping the technological knowledge alive might very well be worth the effort. What I am worried about though is that hyping this collider for more than it will probably be is very dangerous. Scientists should state clearly that the chances to find new physics are at best unknown and it would not be a surprise if such a machine just pushed limits. In this respect, one could think of lobbying rather for either building another collider (e.g. CLIC or a muon collider) or for investing the money into accellerator technology research or alternative experiments.

  20. JohnB says:

    Given the enormously successful history of particle accelerator discoveries, right up to the LHC, isn’t the right approach to experimentation, to just keep on building bigger and bigger accelerators (lets say 10x as powerful as the previous one, if there are no solid predictions for new particles), until a project finally fails and nothing is discovered?

    If the available beyond-SM theories are inadequate, all you’ve got left is experimentation – and once experimentation fails (still doing more than well enough there, to justify a new generation of accelerators…), the primary focus will have to shift back onto applied-physics/material-development, aimed at developing accelerator tech, that is a couple/few orders of magnitude better than the last failed experiment (likely a multi-generational effort – unless theory advances and gives some new solid predictions).

  21. Scott Church says:

    Chris, I agree… those are the points I was trying to make earlier. This isn’t a question of what is, and is not worth funding–I think we all agree that the search for new physics up to and including GUT scale, is. The real questions are;

    1) Is it possible to get there from here with the technical means available to us today and for the foreseeable future?

    2) Are we pursuing said new physics down the right paths, with the right technologies, and on a potentially fruitful theoretical basis?

    3) Given 1) and 2), is funding for such endeavors possible, and who will do so?

    The answers to 1) and 2) are anything but clear. Indeed, as Chris said, given what we know of the SM today and the lack of fruitfulness the whole M-theory framework has returned to date, render it likely that we aren’t going to find anything this side of GUT/Planck scales. And that leaves us with 3)… which is a sorry business because we’re left with trying to sell funding for ever larger collider projects to governments that are already strapped, and rightly or wrongly, not in a mood to invest in projects for which we can’t guarantee big returns.

    Radioactive, I feel your pain. I agree that budgets are for accountants, and in my heart I don’t give a damn about political feasibility either. Unfortunately, unless our personal checking accounts are larger than the GDP of a middle-sized nation–a claim few of us can make–we don’t have the luxury of indulging such a stance. Like it or not, we’re going to end up dealing with accountants… Treasury Dept. accountants… who report to world leaders indentured to their electoral base and already up to their necks in failing social security, a collapsing Greek economy, etc. etc. etc. It sucks, I know. But the sad reality is that we aren’t going to get donuts delivered to the CERN lobby next week, much less funding for colliders and other projects, unless we convince those folks to agree to signing the checks. How do we deal with that? I have no idea… but we certainly don’t have the luxury of pretending that we can continue to move forward without doing so.

    While these are important concerns, I think it’s just as important for us to continue exploring other ways we might push back the boundaries. For instance, pursuing advances in cosmological observation and detection technologies that might allow us to peer deeper into primordial events where the energies we can’t reach today with colliders were the rule; Or exploring other theoretical avenues that might bear more testable fruit than M-theory. Regardless of what we can, or cannot achieve with ever larger and more costly colliders, these are things that are within our reach today… and perhaps, more likely to convince those who sign checks.

  22. Dom says:

    On the subject of the output of colliders, Jon Butterworth’s latest article in the Guardian is quite nice Guardian Higgs Article

  23. Peter Woit says:

    Frank Quednau,
    I don’t know, but two people who might are Goncharov, who was involved in the “amplituhedron” business, and Deligne, who I hear was talking to him about this stuff, and knows this kind of mathematics.

    Daniel Tung,
    I just don’t see any evidence at all that you can explain anything about the standard model this way. Much of our understanding of the standard model is based on its symmetries and I suspect that a deeper understanding will come from a deeper understanding of these symmetries. Arkani-Hamed’s speculation ignores these completely (he’s been known to say very unkind things about gauge symmetry…).

  24. srp says:

    It’s encouraging to hear a couple of breaths of rationality vis a vis the obvious next step of investing in the exploration of advanced accelerator technologies. These could end up finding paths to ultra-high energies that cost much less, plus they are more likely to create new spin-off benefits than simply scaling up the existing designs. It would be irrational to commit to spending $15 billion on a the Big Dumb Accelerator without first investing a few hundred million bucks to find out if there were a better and cheaper way.

  25. Peter Woit says:


    Spending a few hundred million dollars to make the problems of why going to higher energies is so expensive go away isn’t an idea that’s been ignored. As far as I know, there just is no idea around such that throwing money at it is going to solve the problems anytime soon. Such ideas are more the sort of thing that will take many decades to see if they will work at all (and certainly should be investigated and funded). But if you want to start building something ten to twenty years out from now, to have it ready when the LHC has been fully exploited, your choices of plausible technology are limited, and all expensive.

  26. Tony Smith says:

    As to Nima’s “… efforts to push forward a Chinese plan to build a next-generation collider …” and “… Gross and Witten have and editorial in the Wall Street Journal … supporting the idea of a Chinese Geat Collider project …”
    Gross and Witten say in WSJ:
    “… China would leap to a leadership position in an important frontier area of basic science. More practically, to build such a massive collider, China would need to develop frontier technology in many fields, from superconducting magnets to high-speed electronic detectors, attracting many of the world’s top scientists and technologists …”.

    Since the USA cancelled the SSC Collider project it has relied on Europe and the LHC for fundamental collider physics, seeing the center of the physics world shift from the USA to Europe.
    Now Nima, Gross and Witten advocate that China, with its increasing wealth and industrial dominance, become the new center of the physics world.

    Why can’t the new center be the USA itself, so that the USA would be the developer of frontier technology and be the center of attraction of the world’s top scientists and technologists?

    Some (maybe including Nima, Gross and Witten) might say that the USA cannot afford such an expensive project, and under current USA policies that might be true, but Citigroup has recently released a note entitled “Cold Fusion” advocating a way to transform the currently “ineffective monetary policy” of the USA into “effective fiscal policy … via central bank monetization … essentially monetizing … spending”.

    The Citigroup plan would allow the USA to undertake many-billion dollar programs (such as the new Great Collider) just as easily as it has undertaken Quantitative Easing to aid its financial sector,
    with the USA reaping the benefits of advancing science and technology.

    As to why Citigroup entitled its note “Cold Fusion”, the note says:
    “… Essentially you are combining Paul Krugman fiscal with Republican tax and Bernanke 2002 … monetary.

    a (very cold) fusion of Krugman macro, Republican tax and Bernanke (2002) monetary policies …”.


  27. Marc says:

    Does going to higher energies really help to understand the standard model?

    This is only true if we discover something new. But will we discover something new?

    We will discover something new if nature has more degrees of freedom at higher energy than at low energy. But is this the case?

    Quantum theory usually does not confirm this. Does nature get more complex at higher energy?

    Usually not. After all, higher energy means lower distance. But it seems obvious from quantum theory that nature will get simpler and simpler at low scale.

    It might well be that the hope to find new things at smaller and smaller scales is ill-founded. In any case, the unification attempts discussed at present (new dimensions, new particles, new symmetries) do not seem to get simpler at small scales, but more complex. We should look for simpler attempts, not for more complicated ones.

  28. Peter Woit says:

    Attempts to turn this comment thread into a tedious political debate about US monetary and fiscal policy will be ruthlessly suppressed.

  29. Neil says:

    Why do Gross and Witten think there is a question about the Higgs mass?

    In any case, the Great Collider would probably cost less than the ISS and produce more science.

  30. Peter Woit says:

    I’d guess that’s a badly done edit, presumably what they meant is that we have no idea why the Higgs mass is 125 GeV.

    One of the main goals of a new collider would be to measure the interactions of the Higgs with itself, something that may be inaccessible at the LHC.

  31. Anon says:

    PW re srp,

    Laser-Driven Particle Accelerators?

  32. Peter Woit says:

    Exactly what I was thinking of as an example of a technology not ready for use anytime soon.

    For a circular machine the fundamental limits are due to the magnets for a proton machine (and there seem to be no prospects of dramatically higher field strengths), or synchrotron radiation for an electron-positron machine (a muon collider would solve this, but the short lifetime of the muon is a huge problem). For a linear machine, to build something much cheaper you need something like such a laser acceleration scheme. Maybe someday this will be doable, but it seems that much more work is needed before one will have a usable technology.

  33. srp says:

    The point is that “much more work” is not being funded. DOE keeps these alternative concepts barely ticking over as theoretical exercises, but there’s not much money or community attention devoted to actually building prototype components, etc., and there is no organized program to figure out the specific roadblocks of the main alternatives, investigate each one to see if there are any showstoppers or to develop solutions, etc. Saying “it’s a lot of work” while systematically preventing the community from doing the work is silly. If you drew out a decision tree for the next-generation accelerator at the energy frontier, there’s no way you would rationally end up spending even a billion dollars on preparatory planning for a scaled-up traditional machine without first spending a fraction of that to try to rule out the practicality of wakefields over the relevant time horizon. I know that Burton Richter has written than some kind of wakefield design is the sensible next step at the energy frontier, but I guess when people reach a certain age in physics its hard to get anyone to listen no matter one’s track record.

  34. Anon says:

    Look, if I had 10-100G dollar I’d like to spend on a scientific project, and you’d manage to somehow convince me that spending on high energy physic is presently more pressing than finding earthlike planets, or quantum computing, or robotic exploration of Titan, or proteomics, or human on mars, or artificial intelligence, or permanent facility on the moon (to name a few project I′m not working on), then you’d still have to convince me it’s not smarter to put my money on laser driven technology first. No one want to build a 100G dollar accelerator, and by the time it’s ready you can use another technology to reach the same target for 1/1000 of the price.

  35. Peter Woit says:

    The question of “why not build a laser (or plasma wakefield, or whatever)-driven linear accelerator to get to the 10 TeV energy scale, instead of the proposed Great Collider”? is a legitimate one. But my impression is that at this point the cost of such a thing is not 1/1000 less, but infinitely more, since no one knows how to do it, at any price. srp is likely right that this kind of research deserves more support, but I’d like to see some sort of realistic time frame + cost estimates for a machine using such a technology. If anyone can point to a convincing document about how such a thing can be designed and built in my lifetime (I figure I’ve got maybe another 25 years or so..), at dramatically less cost, I’d like to see it. And, by the way, claims of “1/1000 the cost” are not confidence inspiring…

    If it’s not at all clear that this can be done, and the timescale for finding out is many decades, then the problem is that a decision to put all the marbles on such a speculative idea is that it may be tantamount to a decision to shut down energy frontier physics for good. The clock is ticking, twenty years or so from now it will not make sense to keep running the LHC, and if there is no viable next generation project on the horizon the field will have to shut down, with trained people changing fields to something else, and no new people being trained.

    I should make clear that I don’t think the case for a 100 TeV machine is at all a slam-dunk one. HEP is facing a very difficult future and some tough decisions. As part of this, I don’t think unfounded claims that a speculative new technology is going to make the problem go away are helpful.

  36. Anon says:

    It’s not confidence inspiring to suggest 1/1000 the cost in the next three decades? Please remember of the human genome project: 3 G dollars in 1990, and 30 years later it would cost not 1/1000, but 1/1000000 the price.

    But on retrospect it’s not fair of me to make this argument, because I’d not support the Great Collider for the next two decades even if you could garantee that the price won’t drop. The main reason? Simply because I don’t see any garantee that it’d significantly increase our knowledge.
    Actually, from reading your blog one could have expected that you thought the same. How then would you justify priorising high energy physics over the many inspiring projects I mentionned previously? Or you think we could all fund them in the next 20 years?

  37. Dave Miller in Sacramento says:


    You wrote:

    a decision to put all the marbles on such a speculative idea is that it may be tantamount to a decision to shut down energy frontier physics for good. The clock is ticking, twenty years or so from now it will not make sense to keep running the LHC, and if there is no viable next generation project on the horizon the field will have to shut down, with trained people changing fields to something else, and no new people being trained.

    Well… for better or worse, I suspect that your statement will turn out to be an accurate prediction of the rest of the century in “high-energy” physics.

    Things have not worked out the way you and I had hoped when we were doctoral students way back when.


  38. Radioactive says:

    Anon: “I’d not support the Great Collider for the next two decades … Simply because I don’t see any garantee that it’d significantly increase our knowledge.”

    So you’d like to defund all speculative research then?

  39. Peter Woit says:

    My view on prioritizing funding is that you have to look at the situation in each field, get a realistic idea of what funds are needed to significantly move forward, decide whether such a level of funding is feasible, then deal with the politics of competing for funding.

    Some fields (like quantum computing) are already hot topics and well-financed, I’m suspicious that there aren’t good ideas out there that aren’t already getting funded. Other fields you mention (e.g. manned space exploration) I personally don’t see as worthwhile at the costs it takes to do them. One way to argue against manned space exploration would be to say “let’s wait to do it until the costs come down by a factor of 1/1000”, but that would be effectively the same as saying “it’s not worth it, so shut the field down”. Better to deal with the difficult actual argument, not evade it, for manned space exploration as for high energy frontier experiment.

  40. Jeff M says:

    Well, I’ve stayed out of this, since I’m a mathematician and we don’t have to worry about funding really. But everyone seems to be dancing around the real issue, which is WHY you fund research. You can do it for the sake of advancing knowledge, or else to advance the well being of humanity/the planet via technology. AFAICT HEP funding is solely based on the first, it’s not like it has any technological implications. Neither does QFT research that I can tell (correct me if I’m wrong). Basic QM, sure, solid state of course, fusion research and nuclear physics in general of course. If you want to argue someone should fund a collider, be honest, the only reason to do it is abstract. Once you do that, you can argue about whether even then it’s worth it, since it’s very unclear that you’re going to get anything from a much bigger collider. Personally, I don’t think you’ve gotten much from the LHC, I mean did anyone expect them not to find the Higgs eventually? And given that nothing else has shown up (and I’m willing to bet you actual money nothing else will) where are you now?

  41. Peter Woit says:

    Actually, QFT research does have a lot of practical applications. Solid state physics is based on it, since the field effectively deals with an infinite number of degrees of freedom, not the finite number of simple QM.

    You need to, when possible, experimentally test an idea like the Higgs mechanism, not just believe it since it seems to be the most plausible idea. Often ideas you think are the most plausible turn out to be wrong (or only part of the story). Besides verifying conjectures about the Higgs mechanism, the LHC has also shot down huge areas of conjecture about TeV scale physics (there’s an interesting ongoing question of when many theorists will acknowledge this reality). With no LHC we’d forever hear that SUSY is the most plausible idea about TeV scale physics and should just be believed.

  42. Scott Church says:

    The Oct. issue of Scientific American has an intriguing article called How Big is Science? From the opening… “Mammoth instruments such as CERN’s Large Hadron Collider are often held up as symbols of the human commitment to decoding the world. But how highly does humanity as a whole actually regard science? How big is science? This is not an easy question to answer, but by gathering what credible data exist, we can approximate an answer.”

    Haven’t had a chance to read it yet, but among other things it discusses some of the issues surrounding funding of large physics projects like the LHC, and how public perceptions impact that. The graphic on the first page alone is enlightening.

  43. Jeff M says:


    Had no clue solid state used QFT’s thanks for correcting me 🙂 As for the Higgs, my point wasn’t that it wasn’t interesting, just that if you were thinking practically it wasn’t going to get you anywhere. As far as the LHC chucking supersymmetry etc. out the window, has that really happened? Aren’t all the SUSY people just running around saying “wait for the next bigger accelerator?” I’m not holding my breath

  44. Pingback: A bit of pushback against the empirical tide | Homines Economici

  45. Anon says:

    Your opinion on how to prioritize funding is perhaps unclear (one way to read it is you’re happy to offload this on political games, but hopefully this is not what you intended to say). I happen to agree on manned mission (except most children trill, and the more they trill the more will turn scientists…), disagree that quantum computing is funded at an appropriate level (I even suspect that, in the long run, progresses in high energy physic will depend on first making a quantum computer work), disagree that not adding 10G USD to a field is the same as shutting the field down.
    No, I’d glad to support the next collider if the cost was 10-100 millions USD.
    Scott Church,
    Great link! This kind of graphic is arguably the best support for the GC, e.g. maybe a new collider “just to check there’s really nothing to see” would be fine after all, if only expanditures on Science were enough to make the F35 program looks cheap.

  46. abby yorker says:

    The article says 10 billion for 100 Tev. LHC cost 13 billion(Forbes). I recommend that we go for a Planck energy machine, to minimize costs.

  47. Peter Woit says:

    Jeff M,
    It’s been a long time since HEP people had a good case that what they were learning about fundamental physics would have practical implications. If those who argued that the LHC would see SUSY try to follow the Gordon Kane model, and try to use it as an argument for the Great Collider, I think they will run into serious questions about their credibility.

    I think it’s the job of physicists to come up with the cheapest way of successfully investigating higher energy scales, and if the budget numbers are plausibly affordable, make their best case to the politicians who will have to sign off on budgetary decisions. I understand the US budgetary and political situation, and it’s clear that there’s no way this kind of project is now doable in the US. I understand nothing about the analogous issues in China, but don’t see an argument why physicists shouldn’t make their case for this.

    abby yorker,
    I think 13 billion is a maximalist way of accounting for LHC expenditures, 10 billion a minimalist estimate. I don’t understand the economics of this well enough to understand the cost differences between doing this kind of thing in Geneva (one of the most expensive places in the world) vs. China.

  48. srp says:

    As between moving the center of experimental HEP to China v. exploring advanced concepts, I’m not sure which one is the riskier bet of all the marbles. ISTM that the technological and economic facts have eliminated the bet-one-marble actions from the strategy space on the energy frontier. One advantage of the advanced concepts is that one cannot be so definitively sure about the lack of technological spinoffs as one is for the scaled-up conventional machines. Work on dielectric concepts, for example, involves building structures similar to the sort handled by the semiconductor industry.

    Moreover, the time lags for such machines (if they turned out to be feasible) would be more concentrated on R&D than on construction because they would be much, much smaller. While a Manhattan Project-style organization chasing down two or three alternative technologies and the relevant engineering would be no joke to manage, the construction, operation, and maintenance of the machine itself ought to be much less of a superhuman feat of coordination than the LHC or the proposed Chinese Gargantuan Collider. In fact, if these time savings were not possible on the back end of the project then that would mean that the entire concept offered no cost savings at all.

  49. Hiro says:

    Linear 1 PeV Muon Collider, will it become a reality or a delusion?

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