What *Should* We Be Worried About?

Back from vacation today, so regular blogging likely to resume. Will start with something quick, a link to material that was posted today.

The Edge web-site annual question feature is out today, with this year’s question What *Should* We Be Worried About?. I wrote something about the “Nightmare Scenario” that HEP is facing if the LHC finds a Standard Model Higgs and nothing else.

Others addressed the same issue, with Lisa Randall writing:

In my specific field of particle physics, everyone is worried. I don’t say that lightly. I’ve been to two conferences within the last week where the future was a major topic of discussion and I’m at another one where it’s on the agenda.

Her specific concern is motivated by her interest in large extra-dimensional theories, for which no evidence has shown up so far at the LHC. If the extra jump by a factor of 6.5/4 in energy that will arrive in 2015 after repairs still shows nothing, this may be the end of the line for such theories for a very long time. The prospects for a higher energy machine are problematic in terms of technology, as well as the political will to pay for them. The overselling of this that went on for many years pre-LHC won’t make it any easier to re-use these theories as an argument for building a new machine.

Amanda Gefter sees no reason to worry. Particle theorists will just move to making progress without experiment, through studying paradoxes of the current theory, with her final example for optimism the recent debate over the “firewall paradox”.

Carlo Rovelli’s contribution explains one problem with this: humans are very good at convincing themselves they have found some wonderful explanation of something (e.g. some resolution of a paradox, like the supposed SUSY solution to the hierarchy problem), when reality actually involves something quite a bit more subtle and unexpected:

A number of my colleagues in theoretical physics have spent their life studying a possible symmetry of nature called “supersymmetry”. Experiments in laboratories like Geneva’s CERN seem now to be pointing more towards the absence than the presence of this symmetry. I have seen lost stares in the eyes of some colleagues: “Could it be?”, how dare Nature not confirm to our imagination?

By the way, when I was in Paris last week I picked up a copy of Rovelli’s wonderful short book that has just come out in France Et si le temps n’existait pas?. It begins with a personal history of how he got into science, from a background in the 1970s disillusion following the flowering of radical ideas in the 1960, a story I found quite interesting, since I’m of the same generation as him. There’s also the story of how some of the ideas of loop quantum gravity developed, and some speculative material about time. Definitely worth looking for if you read French and are interested in these topics.

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59 Responses to What *Should* We Be Worried About?

  1. Peter Woit says:

    chris,

    I think a crucial question is the magnitude of the cost of going to higher energy. Can this be done within the current size of the CERN budget? For instance the idea of a higher energy LHC (HE-LHC) in the same tunnel might be one that could be funded without significantly increasing the CERN budget (to be clear, I don’t know if this is true), especially since it takes a long time to build these things, spreading the cost out over many years.

    Without some specific important new target to justify a higher energy machine, I think it’s going to be very hard to make the case for lots more money for such a thing (except maybe for the Japanese, who may have good financial reasons to print a lot more money…). On the other hand, once the LHC has done what it can, do you just start shutting down large parts of CERN and firing most of the staff there, or do you pursue a viable way to investigate higher energies, even given a large probability you’re not going to find something exciting?

  2. Thomas Larsson says:

    That a science comes to a halt when it reaches its boundaries is neither strange nor unprecedented. The obvious example is of course geography. Few modern geographers strive to become a new Columbus or James Cook, and those who do are hardly taken seriously.

    In fact, we are now seeing a prediction of John Horgan pan out. After the end of science, scientists will do boring things, but they will never admit that it is boring.

  3. Tmark48 says:

    Thomas Larsson said : “In fact, we are now seeing a prediction of John Horgan pan out. After the end of science, scientists will do boring things, but they will never admit that it is boring.”

    -
    Didn’t historians witness the end of history when the Soviet Union collapsed and the old world order went into pieces ? Seriously, I don’t think that confirming the SM will be the end of science. It will make HEP less relevant but scientific research will go on. Investing in other branches of physics. It’s a natural cycle I think, scary for some but necessary.

  4. Bernhard says:

    What we need in HEP is a real breakthrough in experimental technology to search for new physics. If accelerators become impractical we have to find a cheaper way to do TeV collisions. The only thing we had guaranteed with the LHC was the Higgs or something else, we should not be too surprised or upset about “just” finding the Higgs. I think experimentalists need to be “blamed” as well for the lack of imagination. The LHC was a brilliant project and a formidable experimental achievement but I hardly see people discussing the problem of how could we invest in promoting solutions to NOT need accelerators (at least huge ones) in the first place. This kind of breakthrough might be decades or a century in the future but might be also closer than we think. But while theorists have been trying all possible things (including some things that can hardly be called science, but anyway), experiments follow the same basic logic of Lawrence, just got a lot bigger (OK, shoot me me for the oversimplification here if you want). We need fresh new ideas on how to do this differently, and we should seriously start promoting this as a challenge for the most brilliant young experimentalists.

  5. srp says:

    Did you notice the “move along, nothing to see here” non-response by DC Perkin? The linked paper had mainstream particle physicists showing that the hadron part of the SM is definitely NOT “passing all the tests.” It is systematically failing them in interesting, not-close-to-the-observational-noise ways at accessible experimental energies. Or maybe the theory “properly understood” would pass them, but the theory is now wrongly understood, in the sense of physicists having an incorrect picture of how its assumptions relate to observable phenomena, which would also seem to be a pretty important problem for high-energy theorists to work on.

    I understand that QCD is a difficult jungle through which to hack, but isn’t that a made-to-order challenge for HEP?

  6. StrangeRep says:

    Hi Peter,

    Thanks to your blog article I started reading some of the other non-physics Edge contributions. Did you read the one by John Tooby? I.e.,

    “Unfriendly Physics, Monsters From The Id, And Self-Organizing Collective
    Delusions”.

    This line near the end:

    “we need to design our next generation scientific institutions to be more
    resistant to self-organizing collective delusions, ”

    seems appropriate, :-), though I have no idea how to do it. :-(

  7. Miguel says:

    Amanda Gefter sees no reason to worry. Particle theorists will just move to making progress without experiment, through studying paradoxes of the current theory, with her final example for optimism the recent debate over the “firewall paradox”.

    Please, no. Theory was “ahead of experiment” for about 40 years (since 1973) and look what that brought us. While theory was though to be ahead it was actually off on a tangent. And then another tangent. And another….

  8. Miguel says:

    P:

    However, hiring in physics departments should be based on quality of work and scientific though, either conceptual and abstract or applying known ideas to a new system (or ideally new ideas to a new system).

    Hiring and research funding is now largely based on bean counters weighing the number of citations by impact factors. That is the real reason why Peter Woit is right to worry about progress in science slowing down. Maybe this is only apparent as the signal to noise ratio goes down as the amount of drivel published to pad CVs grows, and the rate of actual advancement of science somewhere remains steady or growing…

  9. P says:

    Hi Miguel,

    No one is going to argue with you on this point. CV padding is not science.

    Regarding your notion of tangent, this isn’t the right viewpoint. It seems your definition of tangent applies to any abstract concept that isn’t directly applied to an experimentally observed system, because that is what a lot of the last 40 years has been, since the standard model works so well. It seems like to you essentially any progress in formal theory is a tangent.

    And there is really no arguing with string theory when it comes to progress in formal theory. Yes – you can argue that it’s not good for phenomenology, though as an expert I can say nearly every argument I’ve seen on this blog is either wrong on some important points or missing important developments from the last ten years. But formal theory – particle physics aside – it has led us to see deep explanations of dualities in field theory, the AdS/CFT correspondence, mirror symmetry, deep properties of scattering amplitudes that Nima argues in a recent paper may apply to N=1 and N=0 theories, etc etc etc. There are many more. These are not tangents or “delusions”, to use Peter’s phrase.

    But more importantly, coming back to the point of this article: we should be very concerned about Higgs + nothing. Not because “it’s not what we wanted” scientifically – we must be fine with whatever effective theory nature hands us – but because it could signal the end of the reductionism approach to experimental particle physics (if new colliders aren’t built). And this would be very sad for humanity, I think.

    For the record, I am very happy that some of the best universities are hiring pure particle theorists the last few years. This is the time to do it, if there ever was one, and there are many excellent new papers on hep-ph. Over the next five to ten years there will be a swing back in the other direction, however. These things are cyclical.

    Cheers,
    P