Nielsen-Ninomiya and the arXiv

Because of the New York Times article discussed here, four recent papers by Nielsen and Ninomiya have been getting a lot of attention in the blogosphere. Pretty much all of it has been unremittingly hostile, when not convinced that these papers must be some sort of joke (except for this from Sean Carroll). I just noticed that these papers have gotten some attention from administrators of the arXiv, who have decided to reclassify three of them, presumably since the appearance of the NYT article.

The first in the series, arXiv:0707.1919 was originally posted in hep-ph, with a cross-listing to hep-th (see the Google cache of Oct. 5), but has now been re-classified as gen-ph (cross-listed as hep-ph and hep-th). Similarly, arXiv:0711.3080 has been reclassified from hep-ph to gen-ph, cross-listed to hep-ph (see Google cache of Sept. 12). I’m not sure what arXiv:0802.2991 was originally classified as, but the Sept. 3 Google cache has it as the same as now, gen-ph, cross-listed to hep-th. Finally, the most recent one, arXiv:0910.0359, was originally classified as hep-ph (Google cache of Oct. 7), now it has been re-classified to gen-ph, cross-listed to hep-ph.

While the arXiv administrators seem to be indicating that they share the common opinion that these are crackpot papers, one thing there does remain constant: trackbacks appear there to various press stories and blog postings about these papers, but trackbacks to this blog seem to be censored.

Update: Trackbacks to blog postings here on this Nielsen-Ninomiya subject have now appeared. The ways of the arXiv remain mysterious to me. About all I can tell is that trackbacks to some sources appear more or less immediately, presumably automatically (for instance the trackbacks to the original NYT article). For other sources, e.g. this one, they only appear in batches, often several days later, presumably after someone has gotten around to considering the matter…

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20 Responses to Nielsen-Ninomiya and the arXiv

  1. Kea says:

    But gen-ph is supposed to be for papers that no serious physicist would read. Why do they bother, given the publicity these papers have?

  2. ManyMe says:

    I am not surprised that Sean Carroll defends the Nielsen-Ninomiya paper.
    He is the expert on the arrow of time problem and the one who can proof the existence of the multiverse by making an omelette.
    And he has a book to sell…

  3. Tim vB says:

    What Sean Carroll says is IMHO correct, the critical path of a hoax is that there is enough content to let it appear to be something interesting, something one can discuss, while leaving enough prove of nonsense to reveal the hoax later. That he does it shows clearly how far off the track some (small) part of the string theory community is.
    Hey, but we can discuss this too, cant’ we?
    First of all: What is time? To stay focused, let’s add “in GR” to the question. Well, you have events, pick A and B, and these can have a causal relationship, meaning: Either A nor B can influence one another, xor (excludive or) A can influence B xor B can influence A. Lets consider A can influence B. Now and only now you can say “A occurs before B”.
    If someone says “we have future and past and the future influences the past” doesn’t that mean that she does not use time as a causal relationship? IMHO the authors should therefore explain what concept of time they use before we can take the diskussion any further. (Since Sean mentons the “non-locality of string theory” this has probably been done, in that case please provide a link, I was not aware of any of this).
    And shurly you noticed that the card drawing game depends on the actions taken depending on the outcome. Meaning, if you draw “don’t operate the LHC” and then decide “well, that was a test, let’s try again”, the experiment is spoiled. It only works if you are really really shure about acting accordingly to what the card says. This connection of the outcome of an experiment to ones state of mind (after the execution of the experiment) clearly takes all physical theories way beyound their realm of applicability.
    If any of the authors reads this, I’d rather be more interested if you have your fun, or if you are embarrassed that the scientific community fell and continues to fall for your hoax (or both, this “or” is not exlusive 🙂
    Does anyone know a desperate unemployed postdoc willing to produce papers of increasing nonsense to test experimentally what will be accepted by established journals? (or the arXiv? or Sean? or LM? – strike the last, the Bogdanovs did that already). If so, I’ll provide my contact information and will happily share my thoughts on the topic.

  4. DB says:

    The Nielsen-Ninomiya papers remind me of an old Larry Niven story, Rotating Cylinders and the Possibility of Global Causality Violation. That title was in turn borrowed from a serious paper by Tipler.

  5. Pingback: Observationally-sacrificed science by consensus, Peter Woit and Sean Carroll as archtypes, those willing to operate past some observationless threshold, which is why resistance from Woit-types can do no more than lead a horse to a different watering hole

  6. Bob Levine says:

    “The Nielsen-Ninomiya papers remind me of an old Larry Niven story, Rotating Cylinders and the Possibility of Global Causality Violation. That title was in turn borrowed from a serious paper by Tipler.”

    I remember that story—very good, one of Niven’s best I thought at the time. But there’s a bit of difference between that and the N/N paper, no? In that story, the relevant planet’s sun goes nova to stop the “tojan horse” give of time-reversal causality from being presented to the enemy. The point was that the universe doesn’t allow time-reversed effects to impinge on its unidirectional causal structure. What N/N seem to be suggesting is the contrary: that the universe itself resorts to time-reversed causal events…

    I gotta say, I find Niven’s take on it a good deal more plausible than the N/N story…

  7. Yatima says:

    The arxiv doesn’t keep a history of its classifications? That’s lousy.

  8. Peter Woit says:


    As far as I can tell, they don’t. I think it’s very unusual for this sort of change to be made, especially for papers that have been posted for a long time (since 2007 in this case).

  9. Coin says:

    DB: I imagine someone’s already mentioned this in one of the previou threads, but isn’t this entire thing basically the plot of Einstein’s Bridge?

  10. zevans says:

    Stephen Baxter – Time – is this idea in reverse, various particle physics events ’caused’ by ‘downstreamers’ ie future selves.

  11. anon. says:

    “… trackbacks appear there to various press stories and blog postings about these papers, but trackbacks to this blog seem to be censored.”

    Your blog doesn’t leave the right impression about string theory, and burying the head in the sand (censoring trackbacks) is the natural reaction to bad news exhibited by the ostrich.

  12. Alejandro Rivero says:

    Yep, penalties in the Arxiv block files seem to be ethernal; yesterday I did not remember my actual password and tried accidentally a blocked one, from years ago: it was there, after five or six years. And I guess it will be after 10 or 30. Probably it is because such bans are “legacy”, from orders received or executed by previous sysadmins.

  13. Peter Woit says:

    Trackbacks to these two blog postings appeared today, I’ve added an update about this to the posting.

  14. Per says:

    Hi Peter,

    I think your attitude is in general a bit to negative. There is no harm in putting these papers on the arXiv. The people who wrote them are respectable scientists, and allowing something like this from them wont open the door for any crackpot to upload something.

  15. srp says:

    The best story about causality from the future is Benford’s Timescape, which as a bonus has actual realistic scientists as its protagonists.

  16. Peter Woit says:


    I agree that there are few enough serious scientists posting utter nonsense like the last Nielsen-Ninomiya paper that there’s no danger they will overwhelm the arXiv. I was just a bit surprised to see it originally posted in hep-ph, thought the moderator would not allow it there, especially since it was number 4 in a series. Not surprised that when it drew attention, it was moderated elsewhere.

    The real problem though is not posting of crackpot papers on the arXiv, there will always be some of those. It’s when these things get taken seriously by some physicists, and picked up by the media that there’s a problem.

  17. Pawl says:

    The NN papers have been criticized for, among other things, introducing “miraculosity” [actually they use “miraculocity”]; if I understand the papers correctly, this term is supposed to refer to the violations of conventional causality, specifically predictability.

    It seems to me that “miraculosity” in a similar (not quite identical) sense should be a problem for brane-world physics. After all, disturbances could appear, to us on the brane, out of the bulk with no apparent (four-dimensional) causation. To suppress these effects, one would need, not only extremely strong constraints on the dynamics, but a theory of what the initial conditions in the bulk were. Ensuring that unwanted “miraculosity” is not present is presumably an extremely strong constraint on branes; I don’t know whether the theory is developed well enough to speak realistically to this.

  18. Chris W. says:

    Pawl’s comment points up what might be the principal value of papers like those of Nielsen and Ninomiya.

    If the proposed theory is afflicted with clearly unacceptable side effects, especially side effects that inspire heated discussion, people might well be prompted to ask what protects some other theories—apparently more worthy of being taken seriously—from similar pathologies. It may be that without further constraints—perhaps unrealizable or unacceptably ad hoc constraints—these other theories will also turn out to be vulnerable. The end result may therefore be to identify good reasons to rule out several heretofore plausible ideas, some of which already have multiple arguments in their favor.

    If this happens, it constitutes genuine progress. Of course, brane-world physics already offers multiple reasons to worry about its ultimate viability.

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  20. Delusion says:

    I argued against a theory of infinite universes a few months ago. If I may briefly summarize myself:

    If infinite universes exist, we must have some means (now or in the future) to access to them to matter. Infinite universes who we cannot exchange energy, matter, or information with are functionally equivalent to this being the only universe, and is therefore metaphysical garbage.

    So, if infinite universes exist, every possible reality that is consistent with fundamental laws of physics is present, an infinite number of times. If infinite universes can have different physical laws, that doesn’t change anything; I’m merely taking the most conservative version of this fantasy into account.

    Since we are assuming that these universes are accessible to one another, there are literally an infinite number of universes whose most powerful inhabitants consider it their sole mission in life to destroy every other universe, and also an infinite number of universes bent only on destroying our very specific universe, and also an infinite number of universes bent only on destroying you and I in this specific universe.

    We’re here, so the infinite universe theory is out.

    In your experience, do most string theorists believe in an infinite universe theory where everything can physically happen does, in another universe? Even so much as the results of chance interaction between fundamental physical particles? Do they perhaps assume an infinite universe theory where the universes don’t have any access to one another, and if they don’t, how do they attempt to reconcile this?

    Or is it the case that most string theorists who believe in multiple universes believe in a finite number of universes (though that number may be staggering), along with Nielsen-Ninomiya?

    To me, the entire subject of infinite universes (or an amount large enough to be functionally similar to infinite) and the idea that we are another race’s model universe, or that we will all be virtually resurrected from a perfect data source smacks of wish fulfillment and a desire for a scientific gloss to wrap around what is effectively a science-fiction version of immortality and afterlife.

    It can make for good science fiction, I suppose.

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