A recent essay in the New York Times by Dennis Overbye has managed to attract quite a bit of attention around the internets — most of it not very positive. It concerns a recent paper by Holger Nielsen and Masao Ninomiya (and some earlier work) discussing a seemingly crazy-sounding proposal — that we should randomly choose a card from a million-card deck and, on the basis of which card we get, decide whether to go forward with the Large Hadron Collider. Responses have ranged from eye-rolling and heavy sighs to cries of outrage, clutching at pearls, and grim warnings that the postmodernists have finally infiltrated the scientific/journalistic establishment, this could be the straw that breaks the back of the Enlightenment camel, and worse.
Since I am quoted (in a rather non-committal way) in the essay, it’s my responsibility to dig into the papers and report back. And my message is: relax! Western civilization will survive. The theory is undeniably crazy — but not crackpot, which is a distinction worth drawing. And an occasional fun essay about speculative science in the Times is not going to send us back to the Dark Ages, or even rank among the top ten thousand dangers along those lines.
The standard Newtonian way of thinking about the laws of physics is in terms of an initial-value problem. You specify the state of the system (positions and velocities) at one moment, then the laws of physics tell you how it will evolve into the future. But there is a completely equivalent alternative, which casts the laws of physics in terms of an action principle. In this formulation, we assign a number — the action — to every possible history of the system throughout time. (The choice of what action to assign is simply the choice of what laws of physics are operative.) Then the allowed histories, the ones that “obey the laws of physics,” are those for which the action is the smallest. That’s the “principle of least action,” and it’s a standard undergraduate exercise to show that it’s utterly equivalent to the initial-value formulation of dynamics.
In quantum mechanics, as you may have heard, things change a tiny bit. Instead of only allowing histories that minimize the action, quantum mechanics (as reformulated by Feynman) tells us to add up the contributions from every possible history, but give larger weight to those with smaller actions. In effect, we blur out the allowed trajectories around the one with absolutely smallest action.
Nielsen and Ninomiya (NN) pull an absolutely speculative idea out of their hats: they ask us to consider what would happen if the action were a complex number, rather than just a real number. Then there would be an imaginary part of the action, in addition to the real part. (This is the square-root-of-minus-one sense of “imaginary,” not the LSD-hallucination sense of “imaginary.”) No real justification — or if there is, it’s sufficiently lost in the mists that I can’t discern it from the recent papers. That’s okay; it’s just the traditional hypothesis-testing that has served science well for a few centuries now. Propose an idea, see where it leads, toss it out if it conflicts with the data, build on it if it seems promising. We don’t know all the laws of physics, so there’s no reason to stand pat.
NN argue that the effect of the imaginary action is to highly suppress the probabilities associated with certain trajectories, even if those trajectories minimize the real action. But it does so in a way that appears nonlocal in spacetime — it’s really the entire trajectory through time that seems to matter, not just what is happening in our local neighborhood. That’s a crucial difference between their version of quantum mechanics and the conventional formulation. But it’s not completely bizarre or unprecedented. Plenty of hints we have about quantum gravity indicate that it really is nonlocal. More prosaically, in everyday statistical mechanics we don’t assign equal weight to every possible trajectory consistent with our current knowledge of the universe; by hypothesis, we only allow those trajectories that have a low entropy in the past. (As readers of this blog should well know by now; and if you don’t, I have a book you should definitely read.)
To make progress with this idea, you have to make a choice for what the imaginary part of the action is supposed to be. Here, in the eyes of this not-quite-expert, NN seem to cheat a little bit. They basically want the imaginary action to look very similar to the real action, but it turns out that this choice is naively ruled out. So they jump through some hoops until they get a more palatable choice of model, with the property that it is basically impotent except where the Higgs boson is concerned. (The Higgs, as a fundamental scalar, interacts differently than other particles, so this isn’t completely ad hoc — just a little bit.) Because they are not actually crackpots, they even admit what they’re doing — in their own words, “Our model with an imaginary part of the action begins with a series of not completely convincing, but still suggestive, assumptions.”
Having invoked the tooth fairy twice — contemplating an imaginary part of the action, then choosing its form so as to only be relevant where the Higgs is concerned — they consider consequences. Remember that the effect of the imaginary action is non-local in time — it depends on what happens throughout the history of the universe, not just here and now. In particular, given their assumptions, it provides a large suppression to any history in which large numbers of Higgs bosons are produced, even if they won’t be produced until some time in the future.
So this model makes a strong prediction: we’re not going to be producing any Higgs bosons. Not because the ordinary dynamical equations of physics prevent it (e.g., because the Higgs is just too massive), but because the specific trajectory on which the universe finds itself is one in which no Higgses are made.
That, of course, runs into the problem that we have every intention of making Higgs bosons, for example at the LHC. Aha, say NN, but notice that we haven’t yet! The Superconducting Supercollider, which could have found the Higgs long ago, was canceled by Congress. And in their December 2007 paper — before the LHC tried to turn on — they very explicitly say that a “natural” accident will come along and break the LHC if we try to turn it on. Well, we know how that turned out.
But NN have an ingenious suggestion for saving us from future accidents at the LHC — which, as they warn, could endanger lives. They propose a card game with more than a million cards, almost all of which say “go ahead, no problem.” But one card says “don’t turn on the LHC!” In their model, the nonlocal effect of the imaginary part of the action is to ensure that the realized history of the universe is one in which the LHC never turns on; but it doesn’t matter why it doesn’t turn on. If we randomly pick one out of a million cards, and honestly promise to follow through on the instructions on the card we pick, and we happen to pick the card that says not to turn it on, and we therefore don’t — that’s a history of the universe that is completely unsuppressed by their mechanism. And if we choose a card that says “go ahead,” well then their theory is falsified. (Unless we try to go ahead and are continually foiled by a series of unfortunate accidents.) Best of all, playing the card game costs almost nothing. But for it to work, we have to be very sincere that we won’t turn on the LHC if that’s what the card says. It’s only a million-to-one chance, after all.
Note that all of this “nonlocal in time,” “receiving signals sent from the future” stuff is a bit of a red herring, at least at the classical level. We often think that the past is set in stone, while the future is still to be determined. But that’s not how the laws of physics operate. If we knew the precise state of the universe, and the exact laws of physics, the future would be as utterly determined as the present (Laplace’s Demon). We only think otherwise because our knowledge of the present state is highly imperfect, consisting as it does as a few pieces of information about the coarse-grained state. (We don’t know the position and velocity of every particle in the universe, or for that matter in any macroscopic object.) So there’s no need to think of NN’s imaginary action as making reference to what happens in the future — all the necessary data are in the present state. What seems weird to us is that the NN mechanism makes crucial use of detailed, non-macroscopic information about the present state; information to which we don’t have access. (Such as, “does this subset of the universe evolve into the Large Hadron Collider?”) That’s not how the physics we know and love actually works, but the setup doesn’t actually rely on propagation of signals backwards in time.
At the end of the day: this theory is crazy. There’s no real reason to believe in an imaginary component to the action with dramatic apparently-nonlocal effects, and even if there were, the specific choice of action contemplated by NN seems rather contrived. But I’m happy to argue that it’s the good kind of crazy. The authors start with a speculative but well-defined idea, and carry it through to its logical conclusions. That’s what scientists are supposed to do. I think that the Bayesian prior probability on their model being right is less than one in a million, so I’m not going to take its predictions very seriously. But the process by which they work those predictions out has been perfectly scientific.
There is another reasonable question, which is whether an essay (not a news story, note) like this in a major media outlet contributes to the erosion of trust in scientists on the part of the general public. I would love to see actual data one way or the other, which went beyond “remarkably, the view of the common man aligns precisely with the view I myself hold.” My own anecdotal observations are pretty unambiguous — the public loves far-out speculations like this, and happily eats them up. (See previous mocking quote, now applied to myself.) It’s always important to distinguish as clearly as possible between what is crazy-sounding but well-established as true — quantum mechanics, relativity, natural selection — and what is crazy-sounding and speculative, even if it’s respectable speculation — inflation, string theory, exobiology. But if that distinction is made, I’ve always found it pretty paternalistic and condescending to claim that we should shield the public from speculative science until it’s been established one way or the other. The public are grown-ups, and we should assume the best of them rather than the worst. There’s nothing wrong with letting them in on the debates about crazy-sounding ideas that we professional scientists enjoy as our stock in trade.
The disappointing thing about the responses to the article is how non-intellectual they have been. I haven’t heard “the NN argument against contributions to the imaginary action that are homogeneous in field types is specious,” or even “I see no reason whatsoever to contemplate imaginary actions, so I’m going to ignore this” (which would be a perfectly defensible stance). It’s been more like “this is completely counter to my everyday experience, therefore it must be crackpot!” That’s not a very sciencey attitude. It certainly would have been incompatible with all sorts of important breakthroughs in physics through the years. The Nielsen/Ninomiya scenario isn’t going to be one of those breakthroughs, I feel pretty sure. But it’s sensible enough that it merits disagreement on the basis of rational arguments, not just rolling of eyes.
All interesting, but the Higgs is a triplet centered at 34.25 TeV, so only a faint sub-harmonic effect could appear at the LHC. This is a strong prediction; definitely not based on as crazy a notion as that of NN. Thus, the non-appearance of the Higgs at the LHC will not be a cause for conCERN…
I have to think that if this complex action and the specific action they chose were true, that the effect would be just to force the production amplitude of the Higgs to zero, not to prevent the construction of a machine that might produce it.
It seems particularly crazy to me since if Higgs bosons would be produced at the LHC, doubtless they’ve been produced many, many times by cosmic rays already.
I rather like Blake’s comment in #19:
While I don’t outright decry this kind of speculative research and I don’t question the credentials of the authors, I do find it somewhat disappointing that simply not being a bonafide crackpot is grounds for being taken seriously enough to get this much attention.
I think NN need some facts or some data (:)) in order to explain better their opinion , but these should be in the future. 🙂
I love the smell of crackpot in the morning!!!
It doesn’t seem to take much to rattle the physicists cage these days.
Einstein was right about the shortcomings of Quantum Mechanics and so therefore String Theory is also the incorrect approach. As an alternative to Quantum Theory there is a new theory that describes and explains the mysteries of physical reality. While not disrespecting the value of Quantum Mechanics as a tool to explain the role of quanta in our universe. This theory states that there is also a classical explanation for the paradoxes such as EPR and the Wave-Particle Duality. The Theory is called the Theory of Super Relativity.
This theory is a philosophical attempt to reconnect the physical universe to realism and deterministic concepts. It explains the mysterious.
Manual TrackBack ping: My Doomsday Weapon.
Why should particle physicists have all the fun? My low-energy AMO experiment has suffered unlikely setbacks, so clearly, I must be on track to destroy the Universe. For a couple of Nobel Prizes, I’ll happily abandon this track, and do something else with my life…
re: Sean #11
you would have to compute the miraculosity of that scenario and compare it to the one of the “collider being held back by accidents” one and compare them. could you really carry that through (even more so without snickering while you do it)?
i think Steuard in #15 is dead on. there is so much structure between the level of the action and the path minimizing it on the one hand and abstract concepts like drawing a card on the other that any casually implied link is destined to be just wrong.
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I haven’t written anything about this until now (not even a comment on a blog), but my response to this is similar to what my response to all such stories is: the media screwed this up, badly, again.
I suspect that a lot of the non-scientific criticism that you see isn’t centred around the researchers themselves (or their work), but rather on the media’s inability to pass along the relevant information in a coherent fashion.
BTW, thanks for writing about this. You explained far better than any MSM source that I’ve read, in words that even I can understand.
This incident is turning into another Bogdanov affair. Like flies to cowpats, it is attracting all kinds of nonsense and fantastic speculation, which has now all been given some small veneer of respectability by the publication of these ravings.
Does theoretical physics belong in the physics department anymore, or should it find a home for itself in Philosophy or one of the other humanities professions?
Thanks for writing this Sean. You certainly did explain it better than I did, albeit in a lot more words.
it’s all more simple, as per nambu, the top quark deconfined does all what the higgs does, and since the Universe is efficient it never makes a particlle we dont need, thus the top quark is the Higgs. And we wont find the higgs. So why so muhc fuss about higgs anndd the god particle. It was pure marketing by leo lederman a smart jewish-american accelerator boss who convinced reagan that they were not the same (lee smolin and zee also proved it – they are the same if we consider a strong field a strong gravitational field in the brans-dicke model). Ergo we wonnt find the higgs but produce copious quanntities of top quarks and all other type of quarks in deconfined state. This might result in the creation of a bose-einstein condensate of quarks, which can trigger an ice-9 type of reactionn and create one of the many possible Einstein frozen stars, strangelets, top quark stars or something not yet well understood that will blow up the earth. And of course 13 billion $ will be thrown to the garbage because our politicians dont know anything about physics and the industry of nuclear machiens dont understand the cold war is over and there are many other ways to explore safely the universe. Bt in the age of marketing you can sell anything. ‘two things i consider infinite, the universe and the stupidity of humans andd im not sure of the latter’ mr. einstein
Here is an excerpt of an interview of Frank Wilczec from the MIT (Nobel laureate 2004) in Newsweek :
“ If you just take the particles we have and extrapolate their known behavior, you run into contradictions–You start to contradict basic principles of quantum mechanics or common sense. There has to be a deviation of some kind from the laws we have at present when you go up to high energy : if there is not a new particle, then we’ll need different laws. That would be maybe even more profound than finding new particles—if we have to give up quantum mechanics or change what we mean by the laws…”
“This incident is turning into another Bogdanov affair.”
Interesting comparison. In l’affaire Bogdanov, a few reviewers and thesis committee members were asleep at the wheel, whereas people commenting on the Internet in their spare time figured out that the Bogdanov papers were pure, elemental bolonium, and could tell you why. (I particularly liked how the grandiose statement about the Big Bang and Foucault pendulums reduced down to “every plane contains a point”. Classy.) The Bogdanovs got a bit of a boost from the “he said, she said” style of the newspaper articles, but were eventually reduced to whining on obscure Usenet groups, quote-mining and mistranslating their critics in their book, and trying to edit their own Wikipedia article under fake names.
Somehow, physics survived.
(1) Crazy ideas like these are great. Nothing like a great thought out of the box to force us to rethink our assumptions.
(2) I am ashamed for Sean that the Grid of Disputation didn’t make an appearance. I would consider NN “Embarrassing Allies”.
(3) And thanks Steaurd #15 !
We need a new paradigm which can lead theoretical physics out of the swamp of string theory, anthropic reasoning, 10^500 imaginary multiverses, ficticious “WIMPS” with choose-whatever-you-like properties, and absolute garbage like the NN papers/hoax.
None of it is scientifically testable in any realistic and non-adjustable way.
I repeat: it is not testable and it is not science.
The new paradigm will be derived from studying NATURE, not from studying Platonic artifice. The new paradigm will make definitive predictions that are unique to the paradigm, non-adjustable, quantitative and can actually be done [in fact the dark matter tests are well underway and significant results are already in]
The new paradigm has been patiently waiting for 33 years for physicists to awaken from their drunken slumber.
Yours in science,
RLO
http://www.amherst.edu/~rloldershaw
I can not comment on the validity of the paper, but I think the communication of ideas and scientific method is paramount.
The occasional “crazy” idea is the very thing that we should try to wrap our brains around. Jimbo #24 points that SciFi is one way we can popularize the science we discuss in papers. I have recently read articles claiming that the lines are blurring between SciFi and other completive literature because notable writers are including speculative elements in there stories. Such stories lead me to science, not the science itself.
Lately, the BBC has been running Carl Sagan’s Cosmos series. At twenty years old, it is still a good documentary, but I can not get my wife or kids interested because it is too slow moving and his delivery is too ponderous.
To promote better discussions in science topics, perhaps we could to popularize the scientific method and critical thinking. Then the discussion about crazy ideas could be more about the idea and less about personal bias.
For supfior :
I did have a look at Super Relativity but it is still working with the ancient model of atom, so my system seems to be better.
See : http://eternal-cartesian.blogspot.com/2009/09/science-and-quantum-mechanics.html
And my “Article 3” on the same blog as the previous link.
Cordially
One point I haven’t seen raised elsewhere. Even if NN’s theory is worth taking seriously, I don’t think that the pick-a-card experiment can ever provide a useful test of it.
The adjustable parameter in the experiment is the number of cards in the deck, or equivalently the probability of picking the turn-off-the-LHC card. For the experiment to work, we have to choose this parameter to be less than the prior probability of NN’s theory being right, since otherwise a positive result won’t lead to a high posterior probability for NN’s theory (i.e., won’t be strong evidence for it). On the other hand, we have to choose the pick-a-card probability to be lower than the probability that the LHC is destroyed in a natural disaster: if we don’t, then presumably NN theory predicts that the universe will “pick” the natural disaster, and the card test will come out negative. I don’t think there’s a sweet spot between these two constraints.
I blather on about this some more at http://blog.richmond.edu/physicsbunn/2009/10/15/is-the-lhc-doomed-by-signals-from-the-future/
As a near-laygeek with a lowly Bsc, it seems pretty clear to me.
Physicists with quasi-crackpot theories, probably cooked up over a couple of beer / sake in a pub and initially scratched on a napkin, followed by a short debate over the bill and tip? Imaginary components of action potentials with nonlocal effects?
Sounds like bistromath to me.
So if this theory pans out, then universe will do anything, probably the least improbable path available, to avoid a higgs boson? And the effect involves nonlocality?
Ye gods! Don’t you see the potential!?!? What we have here is the makings of an Infinite Improbability Drive, as conceived by the late great natural philosopher, Douglas Adams!
THE UNIVERSE IS OURS! 😀
Sean, this paper is really crap and you should name it this way.
As a previous commentator stated, many Higgs have probably been produced in cosmic rays. So if the LHC is supposed to be prevented from producing them because they are dangerous or because God does not like them, then what about the cosmic rays? Sean asked how do we know that they are produced in cosmic rays? Well, we don’t, but we do know that if the LHC is energetic enough to produce them then they can most certainly be produced in cosmic ray collisions with the atmosphere.
Maybe the point is to sabotage the field of high-energy physics instead by preventing the discovery, thus undermining funding…..one wonders why the same mechanism didn’t prevent the development of the atomic bomb if it were really true.
>crickets<
Huh, tough crowd.