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.
The pick-a-card approach seems insufficiently ambitious. Surely if we can force a one-in-a-million event we can do better. What are the odds that (a) the US and Russia agree to eliminate all nuclear weapons, (b) actual global warming turns out to be in the lowest 0.1% of the forecast range, (c) Eva Longoria falls madly in love with a top LHC researcher, (d) Barack Obama resigns/wins the Nobel Peace Prize/is assassinated/ends up serving 5 terms, (e) some wealthy eccentric decides to give everyone on the CCERN project a Lexus? Pick according to your tastes, or estiamte joint probabilities — maybe you can get several, if you fully and sincerely commit to not turning the machine on in return.
Aren’t there some SF writers who read this blog?
OK I like following physics but will state I just don’t understand way to much of it. That is why I come here and some other places to try and learn more. (I am a class A Mathtard so I can’t understand much of physics, but that doesn’t stop me from trying to understand what I can).
My problem with the NYT article is limited to paragraphs (at least in the print screen) 5,6, and 12. They are ill conceived in that they provide no context. Why would “God” or “Nature” give a flying fluffy duck whether there is or is not a Higgs? And what is the physicist’s definition of bad luck? Luck is not luck, it is possibilities and probabilities, BTW I’m using a very layman’s understanding here. Forgive the bad analogy to follow, it is entirely possible my quantum wave function (thingie) will suddenly match that of my chair and I will melt through it and hit the floor. Now the probability that occurring will likely take longer than 10^bagillon years though. But that doesn’t mean it can’t happen in the next 10 secs……ARGHGHHG, sorry bad of me I know. Or conversely I should win an average 50% of every coin toss I bet on, but that doesn’t mean I can’t loose everyone of them for the same 10^bagillon years either, its just not probable. I doubt I wrote that right but you probably understand the sentiment.
What the abovel meant is in the article N&N and the author are using words that should have no rational use science and that many people like me can use against science. That’s my problem with the article.
I am really glad you wrote this post. It’s distressing to see how many people think the work was a hoax or joke or simply illogical. It’s unfortunate that the NN paper is being called crackpot science by lay people because it goes against standard intuition, while blatant crackpot science somehow goes unnoticed by the same audience, because it’s familiar from works of science-fiction.
I agree that they do suggest something awfully crazy, but the only part of it that I would say wasn’t still based on proper foundations was that ad hoc action they choose. Still, more absurd assertions have been made in physics’s past and didn’t cause nearly as much grief (not that I would agree with ‘ad hoc’ principals having a place in rigorous science, mind you).
Even incredibly unlikely scenarios have a right to be discussed, as long as they are done with an appropriate consideration of the fundamental laws and mathematics that govern them. That discussion, the intelligent, well formulated, rigorous, inquisitive discussion IS science. It’s unfortunate that so many “fans” of science seem to forget that when something uncomfortable is introduced.
So what are subatomic particles “made of”?
I thought it was well known what particles are made of:
http://www.youtube.com/watch?v=OTzLVIc-O5E
1) Ted Bunn: Isn’t there some kind of path math that forces us to choose the right number of cards?
2) cybertraveller777: “So what are subatomic particles “made of”?”: I’ll go with Baltay at Columbia who argued that quarks were made of earth, air, fire and water.
I’ve got it!
Nature does not abhor the “Higgs”. Nature abhors string theorists and is causing them to humiliate themselves. Note: no backwards causality in this theory.
Scientific evidence:
1. Holger Nielsen’s excursions into la-la land
2. Lenny Susskind’s amazingly fatuous article in Physics World drawing parallels between string theory and Darwin’s Theory of Evolution. Talk about the sublime and the ridiculous!
3. Hundreds of equally dubious “cat’s cradles” submitted to arXiv.
Brace yourself, Toto. Nature is striking back!
😉
RLO
http://www.amherst.edu/~rloldershaw
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Steuard said: “Even if they’re right that the LHC will fail to produce the Higgs for this reason, I don’t for one minute believe that their theory can actually predict that a one in a million card draw would be the universe’s preferred way to make that happen (as opposed to “bad luck” preventing each potential production event, or another magnet failure, or for that matter global war or economic collapse). ”
Correct. And that’s why this thing is crackpottery and not just “weird science”: their conclusions obviously don’t follow from their assumptions.
But: that’s nothing rare in physics these days. Making grandiose claims that don’t follow from your theory is a whole industry in itself.
Sean said: ” 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.”
HBN: “Dear CERN director, please perform this experiment.”
DIRECTOR: “Sure, why not?”
HBN: “But you have to be sincere.”
DIRECTOR: “I am sincere”
HBN: “We will have to measure your sincereosity, a new quantum number.”
DIRECTOR: “No problem, I have an ACME sincerometer right here under my desk….”
All of the above ravers & naysayers, should open Jackson & refresh themselves about `Advanced Potentials’, an utterly natural solution in classical electrodynamics, in which EM waves are detected BEFORE the charges which emit them accelerate. They are dual to and on par with the `Retarded Potentials’ which are the causal solutions to the same wave equation. Seems reasonable enuf, but only ONE expt. in the last 40 yrs has tested the validity of the former, and falsified it. Really ? No Others ? One other has tested it and validated it (`07). The response: deafening silence. Sounds like closed minds to me…..
The history of modern physics is that of one common sensical paradigm after another being overturned. The naysayers initially bombard the pioneers with stones & accusations of `crackpot’ , but often canonize them later.
Can causality, the most sacred paradigm, be far behind ? Minds as they say, are like parachutes: They only work when open.
>Sean said: ” 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.”
That’s easy. Sincerity only requires you to obtain one quantum number generator, a microcontroller, and 100kg of TNT, and place said assembly inside the LHC’s detector.
The problem being, as noted above, that the risk of nuclear war is probably above 1% in any given year, so you’re going to need to set odds of say 1/25 that the TNT would go off.
From a practical point of view, a million card deck is unwieldy. Wouldn’t it be easier to draw one card from a hundred deck three times in a row?
Kaleberg asks me “Isn’t there some kind of path math that forces us to choose the right number of cards?”
I don’t think I understand the question. For any given values of the prior on NN’s theory and the probability that something else destroys the LHC, presumably it’s possible to compute the optimal number of cards in the deck (i.e., the one that would provide the strongest possible evidence in favor of NN’s theory). What I’m saying is that even that optimal choice will still provide only very weak evidence.
Jimbo,
“Advanced potentials” are are product of abstract mathematics, i.e., Platonic artifice.
I would be willing to bet my life that they have no reality in nature.
If you give up causality, you might as well give up science, having forgone sanity already.
Is it reasonable to empirically test for “advanced potentials” and other subtleties relating to causality? Absolutely!
But in science it’s: false until proven true [or at least supported by adequate empirical evidence]. Not the other way around!!
And consider this advice, which theoretical physicists have been oblivious of for decades: mathematics can mislead as much as it can elucidate.
Yours in science,
RLO
http://www.amherst.edu/~rloldershaw
Robert L Oldershaw:
“Have you ever considered the possibility that the “Higgs particle” has no basis in reality?
Is it perhaps like “magnetic monopole particles”, where we spend many millions of dollars chasing a theoretical mirage?
The “God Particle”? More likely the “Unicorn Particle”.
Perhaps nature does not “abhor the Higgs”; it’s just that nature hasn’t the slightest idea what you are talking about.”
Funnily enough, it seems that the magnetic monopole has been discovered. see:
http://news.bbc.co.uk/1/hi/technology/8307804.stm
http://www.nature.com/nature/journal/v461/n7266/full/nature08500.html
I think most physicists acknowledge the possibility that certain theoretical particles dont exist. However, giving up gets us nowhere.
oops, i meant “may not” rather than “dont” exist.
All this reminds me of a joke I read in a nice collection of science-oriented humor many years ago. It goes something like this:
A guy pays a visit to a scientist (and friend) one day at the scientist’s laboratory. The guy is surprised on his arrival at the lab’s door to see a rabbit’s foot hanging from a hook on the door. He enters, and asks his friend whether he actually believes that a rabbit’s foot will bring good luck. The scientist replies: “No, I don’t, but I’ve heard that it works even if you don’t believe in it.”
PS: Following comment #60, what does sincerity have to do with anything? One doesn’t decide, or sincerely wish, to obey the laws of physics. One simply behaves, and makes whatever choices one wants in hope of achieving certain results, and certain consequences follow, while others do not. The laws of physics are what describe the ultimate objective constraints on the consequences. (The term “law” is unfortunate, inasmuch as it invokes in some people’s minds a misleading analogy with legislated constraints on human activities.)
John and Joanne, what do you think of this paper(since both of you are actively working
on LHC experiment/phenomenology). What do people on LHC think of this paper?
Thanks
Huey,
If you study credible scientific accounts [e.g., in Nature] of the discovery of magnetic monopole-like systems in spin ices [which are confined to the spin ices, to boot], you will find that what has been discovered is a very, very long way from a Dirac-type magnetic monopole PARTICLE.
No one is claiming to have discovered the latter mythical unicorn.
The devil is in the details! Right?
Yours in science,
RLO
http://www.amherst.edu/~rloldershaw
What a scientist notices something hasn’t happened yet, puts forward a completely out there explanation for it (which politically plays into the hands of naysayers who say the goal is impossible and/or dangerous), despite the fact that there are considerably more banal explanations? Sounds familiar.
Perhaps Nielsen and Ninomiya are correct, but in context, intelligent thinking people have every right to mock the idea that the failures of the LHC and the withdrawal of funding from the Superconducting collider is reasonable evidence to infer that Nature abhors a Higgs, and propose seriously an experiment to shut down the LHC.
68: Sincerity does matter, actually. Their point was that the likelihood of randomly drawing the 1 in a million card would be increased because it would be a way to suppress large numbers of Higgs in the future. If you’re not sincere about stopping the experiment, then the choice of that card would not suppress future Higgs’, and hence would have no effect.
Hi Sean,
“Marc, how do you know they’ve been produced? It’s only very likely, given the conventional rules of quantum mechanics”
That’s probably the most interesting point made about Nielsen’s and Ninomiya’s conjecture within the Quantum Mechanical backdrop, which is to ask if this serves to prohibit the production of the Higg’s or rather only being certain in the knowledge of its existence. That is to consider if this is actually physical prohibition or simply conceptual censorship? Being a DeBroglie-Bohm fan and as its consistent with what David Albert has demonstrated, this would suggest that rather then nature lacking determinacy, it rather instead having its own private will.:-)
Best,
Phil
this should be easy to understand if you are remotely educated.
the real question here is, “should we gamble?”
putting your socks on in the mourning has no risk?
you do not know that someone has not let a poisonous spider under your door overnite, now do you?
keeping in mind that the rule of the universe is pattern, and pattern is stoneage, and there is no point to life, (if there was a point you would be slave to the point?)and what do you do about pointless things, (which proves that there are no intelligent aliens, as such always develop the technology to take their home planet out of orbit) what is the grand benefit to anyone if we do gamble?
does anyone know?
Just as a follow up to what I just said, you might say that if the deBroglie-Bohm picture were true, then the NN’s card trick wouldn’t be of any help. That being resultant of course that in this case nature wouldn’t be willing to show its hand. The again, what would constitute in representing being a good bluff?