One of my colleagues at the NBI had an unusual experience: one of his papers took a full year to get through peer review. This happens often in math, where reviewers will diligently check proofs for errors, but it’s quite rare in physics: usually the path from writing to publication is much shorter. Then again, the delays shouldn’t have been too surprising for him, given what he was arguing.
My colleague Mohamed Rameez, along with Jacques Colin, Roya Mohayaee, and Subir Sarkar, wants to argue against one of the most famous astronomical discoveries of the last few decades: that the expansion of our universe is accelerating, and thus that an unknown “dark energy” fills the universe. They argue that one of the key pieces of evidence used to prove acceleration is mistaken: that a large region of the universe around us is in fact “flowing” in one direction, and that tricked astronomers into thinking its expansion was accelerating. You might remember a paper making a related argument back in 2016. I didn’t like the media reaction to that paper, and my post triggered a response by the authors, one of whom (Sarkar) is on this paper as well.
I’m not an astronomer or an astrophysicist. I’m not qualified to comment on their argument, and I won’t. I’d still like to know whether they’re right, though. And that means figuring out which experts to trust.
Pick anything we know in physics, and you’ll find at least one person who disagrees. I don’t mean a crackpot, though they exist too. I mean an actual expert who is convinced the rest of the field is wrong. A contrarian, if you will.
I used to be very unsympathetic to these people. I was convinced that the big results of a field are rarely wrong, because of how much is built off of them. I thought that even if a field was using dodgy methods or sloppy reasoning, the big results are used in so many different situations that if they were wrong they would have to be noticed. I’d argue that if you want to overturn one of these big claims you have to disprove not just the result itself, but every other success the field has ever made.
I still believe that, somewhat. But there are a lot of contrarians here at the Niels Bohr Institute. And I’ve started to appreciate what drives them.
The thing is, no scientific result is ever as clean as it ought to be. Everything we do is jury-rigged. We’re almost never experts in everything we’re trying to do, so we often don’t know the best method. Instead, we approximate and guess, we find rough shortcuts and don’t check if they make sense. This can take us far sometimes, sure…but it can also backfire spectacularly.
The contrarians I’ve known got their inspiration from one of those backfires. They saw a result, a respected mainstream result, and they found a glaring screw-up. Maybe it was an approximation that didn’t make any sense, or a statistical measure that was totally inappropriate. Whatever it was, it got them to dig deeper, and suddenly they saw screw-ups all over the place. When they pointed out these problems, at best the people they accused didn’t understand. At worst they got offended. Instead of cooperation, the contrarians are told they can’t possibly know what they’re talking about, and ignored. Eventually, they conclude the entire sub-field is broken.
Are they right?
Not always. They can’t be, for every claim you can find a contrarian, believing them all would be a contradiction.
Often, they’re right about the screw-ups. They’re right that there’s a cleaner, more proper way to do that calculation, a statistical measure more suited to the problem. And often, doing things right raises subtleties, means that the big important result everyone believed looks a bit less impressive.
Still, that’s not the same as ruling out the result entirely. And despite all the screw-ups, the main result is still often correct. Often, it’s justified not by the original, screwed-up argument, but by newer evidence from a different direction. Often, the sub-field has grown to a point that the original screwed-up argument doesn’t really matter anymore.
Often, but again, not always.
I still don’t know whether to trust the contrarians. I still lean towards expecting fields to sort themselves out, to thinking that error alone can’t sustain long-term research. But I’m keeping a more open mind now. I’m waiting to see how far the contrarians go.
One thing that gives me hope is that we are living in an age where we have a firehose of new observational astronomy data comes in every work day, and astronomy has small enough consortia and enough more or less independent players to discourage group think to the extent that it is possible to do so. Data is still driving theory, instead of the other way around as in HEP. And, that data has left a lot of previously popular theories on the cutting room floor. This is as it should be in the one part of fundamental physics were we know to moral certainty that there is some sort of new physics out there to be discovered, instead of HEP world which is full of p-hacking and pursuing bumps that disappear when their global statistical significance is considered, in a community where a very small number of experiments are doing almost all the heavy lifting and subjecting the community to group think in the process.
This data has overturned a lot of conventional wisdom which is forcing theorists to try harder. Galaxy sized inferred dark matter distributions do not have NFW distributions. Pretty much all of the naive SUSY predictions for dark matter candidates have not panned out. Inferred dark matter distributions are closely correlated with ordinary matter distributions despite theoretically having almost no non-gravitational interactions with it. Wide binary stars don’t behave the way that they are supposed to behave in either Newtonian or GR physics. One “would be” DM annihilation signal after another has been ruled out and attributed to more conventional sources. 21cm data is consistent with no DM and inconsistent with a conventional DM explanation. The rotational acceleration relation is tighter than it is easy to explain. Galaxy formation starts sooner than it should. Too many galactic clusters are colliding faster than expected. Intermediate sized black holes collider more often than we expected. Some dwarf galaxies appear to have little or no inferred DM and we aren’t sure why. The extent to which elliptical galaxies deviate from spheres correlates with higher M/L ratios. Etc.
On the other hand, the frustrating piece for the moment is that the integration of dissemination of this data is seriously retarded. Too little of the data is making it into widely read review papers. Theorists routinely propose theories that are already inconsistent with observation based upon other people’s papers that they haven’t read and don’t discuss. Rehashes of dead ends are published daily and don’t push the frontier forward, but are published, because lots of people in the field are familiar with them. It is also frustrating to see drift from support for the empirical evidence driven scientific method in favor of more esoteric paths to truth.
Similarly, it is disappointing to me to see so few theorists wiling to attempt to rigorously constrain themselves to exclusively the existing fundamental particles of the SM plus a graviton, given the absence of strong evidence for anything else. Sure, somebody should be out there considering ways to break the rules will new particles and forces we’ve never glimpsed. But something is wrong when those folks are 95% of the community, while the folks willing to work with a minimal set of particles, all of which have been observed, discovered and are sufficient to explain very nearly everything, is less than 5% of the community by my estimation. Also, while there are some good reasons for it, it is ironic that QCD experiments, where the rate at which predictions and experimental results are more often at odds than anyplace else in fundamental physics, seems to produce the smallest volume of new physics proposals.
I’ll tout just one contrarian who deserves a closer look and has good ideas, but not enough resources and support to pursue them properly, because he’s working outside of his primary specialty with ideas that no one else has developed or examined very well.
A recent pre-print of his, for example, discusses a fascinating possible explanation for dark energy phenomena that is so structurally different despite probably producing the right predictions, that nobody else has kicked the tires to see if it really works. In a nutshell, Deur argues that dark matter is basically a consequence of the self-interactions of gravitons that congregate at excessive densities in systems with lots of inferred dark matter, and that dark energy happens because the gravitons diverted to holding galaxies together more tightly than Kepler would predict are therefore not available to provide a full strength gravitational pull between gravity. Thus, this explains dark energy without running into the conservation of mass-energy issues of pretty much all other dark energy theories. See A. Deur, “A possible explanation for dark matter and dark energy consistent with the Standard Model of particle physics and General Relativity” https://arxiv.org/abs/1709.02481v1 (August 14, 2018) (Proceeding for a presentation given at Duke University, Apr. 2014. Based on A. D. PLB B676, 21 (2009); A.D, MNRAS, 438, 1535 (2014)). (Spoiler alert it isn’t really consistent with General Relativity as conventionally applied in several specific respects.) But, nobody’s don’t the tricky N-body models that would be necessary to test this huge departure from the mainstream to explain dark energy.
A more general summary of Deur’s body of work on gravity with an annotated bibliography can be found at http://dispatchesfromturtleisland.blogspot.com/p/deurs-work-on-gravity-and-related.html
I would just like to point out that in my naive interpretation, amplitudologists, at least certain ones, can be just a little bit contrarian:
-We don’t need a Lagrangian
-We don’t need Feynman Diagrams
-We don’t need off shell momentum
-Local gauge degrees of freedom are not a symmetry they are a redundancy
-QM and Unitarity are emergent.
You can probably think of more examples that I can.
LikeLiked by 2 people
One contrarian approach to DE is Wiltshire’s timescape cosmology. It explains the acceleration as an effect of the inhomogeneity. The voids expand faster than their borders, and if one ignores this inhomogeneity, and works with a homogeneous approximation, this distorts the results toward an acceleration if the observer is near the borders (as we are), beginning with the time when the voids become relevant.
My problem: Once Wiltshire has made the computations, and claims that the effect is large enough to explain the data without dark energy, it is obvious that one has to take the inhomogeneities into account. And this would somehow change the amount of dark energy necessary. And the place of any computation based on a homogeneous universe would be the dustbin. My impression is that, instead of redoing all the computations given that this is necessary, he seems to be ignored as a contrarian. But that would only be legitimate if the effect of inhomogeneity would be too small to be relevant, and even this is something which one would have to prove with explicit computations, instead of simply ignoring this.
I’m a contrarian too, even a rather extreme one, see https://ilja-schmelzer.de/. And I have a similar problem: Total ignorance. Nobody even tried to find any error or tried to show that my theory is not viable. It is simply too far away from the mainstream.
Note that there is an important economic explanation for such ignorance: If you live on grants, thus, have to care about getting a new job every two years or so, you have no choice but to follow the mainstream. You have to publish, but publishing is much more difficult in a contrarian direction. The contrarian offers neither conferences where one can publish conference proceedings, nor journals with sympathetic redactors and reviewers, nor own grants. Thus, supporting contrarians is simply very risky. See https://ilja-schmelzer.de/papers/independenceOfScience.pdf
Such wrong economic incentives give good reasons to take contrarians much more seriously than this was justified in the past when scientists usually had permanent positions as university teachers or so.
For the record: I deleted a comment at the author’s request, as well as a comment responding to it. I understand the author regretted some of the wording, and may have further comments later.