Lubos Motl is getting rather concerned (yes, I know about what pops up when I link to his blog…) about recent trends in theoretical physics, especially the implications of recent work (discussed here) of well-known string theorist Erik Verlinde. He claims that many other string theorists share his concern:
The people whose knowledge and opinions about physics are close to mine are finally beginning to realize the worrisome trends affecting the quality and character of the research in theoretical physics. I have a significant number of e-mail exchanges with these folks – and let me assure everyone that you’re not alone.
In many ways I also share Lubos’s concern. Like lots of people, over the years I’ve been deluged with examples of what I’ll call “unconventional physics”, in a spectrum ranging from utter idiocy to serious but flawed work. Much of it shares the all-too-common feature of making grandiose claims for new understanding of fundamental physics, based on vague ideas that often use not much more than a few pieces of high-school level physics and mathematics. The beautiful and deep physical and mathematical ideas that go into the Standard Model are ignored or thrown out the window. In many cases, it’s hard not to suspect that the authors have decided that they can replace modern physics, without bothering to take the trouble to learn what it is. This kind of thing is pretty easy to quickly identify and decide to ignore, and it ends up having no impact on the scientific research community.
In recent years though, some theorists who definitely understand and have made contributions to modern physics have started promoting research which looks depressingly like the typical sad examples of “unconventional physics”. Many of the products of the ongoing multiverse mania fit into this category. Lubos is getting quite worried to see that a very talented and well-known leader of the string theory community, Erik Verlinde, seems to be engaging in this sort of research, and getting positive attention for it. Within a month of its appearance, Verlinde’s “Entropic Force” paper has already generated a dozen or so preprints from other physicists on the same topic. It could easily end up being the most influential (in the sense of heavily referenced) paper of 2010. Seeing this coming from a string theorist he admires is worrying Lubos and his correspondents.
While I agree with Lubos that this is something worth worrying about, his interpretation of the problem is characteristically irrational. In his posting, he argues that this is all due to the influence of the “notorious crackpots” Lee Smolin and Peter Woit. I don’t see how I’m supposed to be responsible for prominent string theorists taking up dubious lines of research I strongly disagree with, other than perhaps having some responsibility for driving them over the edge. In any case, Lubos concentrates his attack on Lee Smolin, arguing that he’s the one mainly responsible for this, an idea which is completely absurd. While Smolin is surely more sympathetic than I am to research like that of Verlinde, he’s a serious scientist and not one with a lot of influence over Verlinde and the string theory community. Lubos’s argument that this is all a left-wing plot organized by the far-left radical hippie Smolin is just laughable. One merciful thing about the string wars always was that positions people took were uncorrelated with their political ideology, keeping politics out of it.
Unlike Lubos though, I’m not convinced that I understand what the source of the problem is. My diagnosis of the current state of the field remains what it was when I wrote my book quite a few years ago: the lack of relevant experimental data coupled with the faddish pursuit of a failed idea about unification has led to a disturbing situation. In a very deep sense though, I just don’t understand why talented physicists react to this by engaging in things like anthropic string landscape research, or vague arguments about “entropic forces”. Lubos is right to notice that this situation has recently become more disturbing. A debate about the causes of this involving people more sober than Lubos would be a good idea. Twenty-some years of string theory hype in the scientific literature and popular press did a lot of damage, and if this gets replaced by hype of ideas even more dubious than string theory unification, things will go from bad to worse. Maybe the LHC will save us, but if this is what it takes, it looks like we’re stuck for a few more years.
This story of relating general relaitivty , to holography and thermodynamics, is god-know-how-many-years-old. There are several papers concerning this matter by Raphael Bousso which has between 100-500 citations. It was intensively used as tests to know if black holes of higher dimensions in SUGRA had the correct entropy. And this not counting just relating GR with thermodynamics, which is even older. Jacobson had papers about this 16 years ago.
Now, I don’t get is what all this fuzz is all about since Verlinde merely made a paper about a super simplified case, using Newtonian gravity…
My guess is that Lubos has done more damage to the reputation of string theory than you and Lee combined. It hardly improves the credibility of your science if a practitioner behaves a lot like the crazy guys on the street corner talking about the end of the world.
I have to say, though, that your snide remarks about the entropy work remind me a lot of what I heard about black hole radiation and Beckenstein’s entropy back when – and yes, I am that old.
Well, if you believe Lubos, Lee is single-handedly responsible for every evil in this world. It’s quite funny actually. Unless you’re Lee I suppose.
Anyway, you know what disturbs me about this isn’t even Verlinde’s paper. I don’t really know what to make out of it, but he has evidently put work into it, it’s thought through, maybe he has a point to make, I don’t know. I don’t get it, but maybe it shouldn’t be dismissed too easily. It probably took quite some courage to put this out. But thing is, I’d usually have ignored it. What I find disturbing is how quickly people are jumping on the topic. I mean, look at this, it’s a matter of weeks! The thing goes through the blogs, is in New Scientist, and so on, and so on. I mean, really, what’s this? The-Making-Of the topic for 2010? After we had Horava-Lifshitz and Unparticles (and whatever happened to that?). I take some comfort of living in a relatively hype-free North European country (there is one person here who reads blogs! No really! But he didn’t know about Cosmic Variance. And he didn’t read your book either. And some other guy read your book but thought Lee wrote it. Or the other way round, forgot.) Now guess what I found on the printer yesterday. Yes, that’s right, Verlinde’s paper 🙂
Verlinder did nothing wrong! He has every right to publish
his results. If you get angry it is your problem. I don’t see
the moral level of our physics community is evidently lower
that in 70’s or 60’s. There are always some very interesting
papers, some less interesting papers, so nothing worths
making fuss about.. In this regard, Verlinder’s paper is
much better than many not-even-wrong papers.
Hi Peter (if I may)
You are way to negative!
Sure, perhaps the Verlinde paper is nonsense, but as Bee said, he did 1) put serious work into it 2) he has atleast prior to this proven he is not an idiot (no matter what one think of string theory) 3) those two facts combined, it wouldn’t really make any sense if he put something really stupid out.
Of course, it could happen, but this off hand dismissal just because it has a totally novel approach I find somewhat, hmm, unscientific.
I’m with bee, the hype is disconcerting. BUT I think the paper itself is refreshing, at least compared to the myriads of conceptually trivial papers that are mathematically sophisticated this is a paper that tries for come real conceptual discussion. And it doesn’t come out of nowhere Ted Jacobson, Black Hole Entropy, holography, etc.. This paper is in good company.
No the problem isn’t with this paper but with the fetishisation of highly technical calculations (not Maths most of the time mind you, just calculations) that add no insight whatsoever. Philosophy is considered a derogatory term (see Polchinskis rant against “word ideas”), and as a result conceptual discussion is automatically labelled crackpot.
It can be. Crackpottery often pretends to be conceptual discussion (though not always, see the Bogdanov affair), but it can be distinguished from genuine, measured, precise debate. Fundamental physics just has forgotten how preferring instead to focus on more “objective” measures like technical skill.
(BTW, since somebody will misread this, technical skill is absolutely highly important, but it seems to me it is emphasized to the detriment of everything else, including, BTW sound mathematical reasoning)
@capitalistimperialistpig
Lubos is pretty much not taken very seriously by many string theorists I know. They recognize him because of his blog, political leanings and his attacks on others more than for any recent physics contributions.
I would worry little about any damage to the reputation of string theory due to Motl. Many consider him to be traveling the road to becoming a crank.
This is pretty obvious from his post moderation, and his contention that people take his blog more seriously than peer reviewed papers. =)
There are reasons why people are getting onto Verlinde’s paper. Partly it’s his prestige, but it’s also partly because there are previous works that are mathematically interesting that people are pointing out, and links into other research directions will be developed progressively. Verlinde has definitely not walked into a vacuum. I imagine that ‘t Hooft and others who have been working with stochastic or random fields will watch developments with interest, as I shall. We’ll find out in a few years (or decades) whether Verlinde has marred his reputation or pointed out a path that becomes interesting and empirically relevant as it becomes increasingly thought through, both mathematically and philosophically.
Although I take your point that “The beautiful and deep physical and mathematical ideas that go into the Standard Model are ignored or thrown out the window”, I think it’s a little too much. A new approach to Physics has to pick something that it can do in an interesting way, then it has to construct a Correspondence Principle between itself and QM/QFT/the standard model that is mathematically elegant and that works well enough to be useful. The second step is very difficult to do well enough, the more so as the conceptual distance is greater. Lee Smolin’s valley has to be crossed. If you had held Planck or Bohr to your standard, we might never have got from classical Physics to QM, since, emphatically, none of that work reconstructed all of classical Physics. The new QM more-or-less solved the Correspondence Problem with classical Physics in the late 1920s, but we still live with the slight failings of our understanding of how that works precisely.
Despite these reservations, good post!
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Maybe it just makes more sense to put heavy theorizing on hold
until the LHC can weed out the unproductive paths .
joel,
I think that has been a lot of people’s attitude for nearly a decade (at one point the LHC start date was 2005), and it hasn’t worked out well. Right now, if everything goes according to plan, it seems likely that significant new information from the LHC won’t come until data from the 2013 run is analyzed and released, possibly in 2014. So, best case scenario is four more wasted years. And then, what if the LHC data just agrees with the Standard Model?
Its not just formal theory that is having quality control problems. A large portion of the phenomenology community spends it’s time shamelessly chasing the statistically insignificant experimental anomaly du jour. Some phenomenologists I know have privately indicated disgust at the situation. I’m not sure exactly how Lee Smolin can be blamed for this, but there must be a way, because he is the devil. But citations for crappy papers are better than no citations for crappy papers not written, so it will continue to get worse before it gets better.
Perhaps the source of the problem is identified in your book: “It is also true that there are no alternatives to superstring theory that one can easily learn and quickly start doing research into. Other ideas remain very little developed, and many of them require dealing with a whole slew of different mathematical ideas that are not part of a physicist’s normal training.” (p. 269 in my copy). “…, since readable expository material about much of modern mathematics is sorely lacking.”, why spend (waste?) years of learning exotic mathematics, if high-school math(s) will do for the time being?
Per,
I’m not critical of the Verlinde paper because it is “totally novel” (which it isn’t), but because I read it and don’t believe you can get a serious scientific theory of the gravitational force from what he starts with (thermodynamics + vague ideas about holography + high school mathematics).
As I wrote in my posting, I don’t understand why a smart, capable scientist is putting out this sort of paper, just as I don’t understand why a lot of other smart, capable people pursue multiverse pseudo-science.
There are a number of instances where simple ‘high school’ calculations can provide significant insight and/or lead to significant advances in a subject. The Jones polynomial for knot invariants can be derived using elementary ideas in geometry (basically three Reidemeister moves) and some trivial algebra. See Kauffman’s work for an easy introduction. However, before the Jones polynomial was discovered in the 80’s, mathematicians toiled with the Alexander polynomial for over 60 years by studying a very formal branch of mathematics dealing with the fundamental group theory of the complement space of a knot embedded in 3-space. I recall it took me a whole semester and about 100 pages of formal theory to just arrive at a rigorous understanding of the Alexander polynomial knot invariant. And despite all this effort, it can’t tell the difference between the trefoil and its mirror image!! (something the Jones polynomial can). Despite its simplicity the Jones polynomial is connected with deep mathematical ideas.
Is this the fate of string theory??
In any case, one can slave away for decades on a highly sophisticated and formal subject that is considered ‘acceptable’ for academic research – and make progress – but if an an alternative idea comes along wrapped up in some simple ‘high school’ mathematics, we shouldn’t be so hasty in rejecting it as ‘nonsense’, especially when there are deep physical insights underlying the arguments….
I don’t really see what’s the trouble here. Why would I complain about someone investing his or her (private!) time in a new approach? If the Higgs ect. is there, then good for the core Standard Model physicists. This model works quite well for what it should do and of course people like that. If one wants to go beyond that in any way – why do other people have a problem with someone who thinks about something not semi-containing the old theory? If it doesn’t work out, I guess it was worth a try still. If it’s just high school mathematics, as you say, then people won’t stick to it like to the string theory unification approach caus then people understand it and understand that it won’t work. I think it’s a bigger problem, that some physicists don’t want to share their last two or three decades of lifetime with something that might seem far fetched, because they learnt something else, the past three decades. old story.
“I read it and don’t believe you can get a serious scientific theory of the gravitational force from what he starts with (thermodynamics + vague ideas about holography + high school mathematics).” So should we have told Einstein not to worry his little head about a trivial, vague thought experiment that compared and contrasted acceleration and gravity, and not to look for a mathematics that makes that intuition into something powerful and useful? Of course not every intuition comes to anything, but, even if you might be right about Verlinde, you’re sounding a little testy here. We can celebrate Verlinde’s voyage even if he might sink. It’s a strange, troubling sport to see you make this particular common cause with Lubos.
To me, the holography is inessential, but the thermodynamics maps directly to geometry, suggests Poincaré’s “Science and Hypothesis”, chapter IV, published in English in 1905, which then, I think, can go beyond high school mathematics. So yes, not so new. On the other hand, string theorists might find Poincaré’s conventionalism a little indigestible.
Peter Morgan,
Personally I find comparing Verlinde’s “entropic force” paper to Einstein’s GR papers just absurd.
In this case, I think Lubos’s evaluation of this sort of research is accurate, and most of the theoretical physics community likely feels the same way. Maybe the ideas Verlinde (and you in your comment) are promoting represent where theoretical physics is headed, but if so I don’t think that’s a good thing.
There are only two kinds of physicists today – those with bad ideas, and those without ideas. Crackpots vs. mediocracy.
Lubos proves that these sets have a non-vanishing intersection.
Standard model is very successful but IMHO it has already reached it’s limits and all attempts to extend it further will fail. I also doubt LHC will find any new physics though it also likely won’t find Higgs or SUSY neither.
It is however not true that there are no experimental observations which need explaining, there are plenty of deep foundational questions which are still unanswered, like: what aspect of physical reality is captured by wavefunction? what is described by fine structure constant? why SM parameters have the values they have? and many more…
I believe such questions have to finally be answered if we are to see further progress. They cannot however be answered in the framework of SM (or the answers would have been found by now), they require a novel approach based on different foundations. And this approach will likely look like crackpotism to those accustomed to SM at first.
This is why I believe unconventional thinking is good and the ideas like ones proposed by Verlinde should be encouraged even if they turn out to be wrong. Wrong ideas can still be beneficial if they inspire others or at least inform them that such and such approach does not work for following reasons.
This doesn’t mean however that anything is worth exploring, speculations which cannot be tested even in principle like multiverse are still worthless and should be discouraged.
Finding successor to SM certainly won’t be easy, it may very well be the most difficult task ever faced by physics what is really unfortunate is that those who chose to work on it face not only technical difficulties but also sociological barriers. Many in physics not only actively avoid foundational questions they also associate such work with crackpots and tend to shun those who try to work on them. This combined with publish or perish attitude makes such work very problematic for young researchers who are most likely to find solutions missed by their predecessors.
All this may significantly delay progress and could also mean that eventual breakthrough will have to come from outside mainstream physics.
Well, what’s their alternative? They could spend another 20 years of their life battering their heads against the rock of modern particle physics with very few results and recognition to show for it; or they could produce and almost as substantial document about “entropic forces” in a hundredth of the time nd for ten times the press. It’s a no-brainer from a game theory perspective at least.
Of course there’s option 3, which is to research in some less grandiose, but no less worthy, branch of physics, e.g. battery research, and produce results potentially of great and immediate worth to mankind. However, this may be quite difficult to do after living in a dreamworld for 30+ years.
I think this whole thread is unfair to physics. Key people in the entropic force business are Ted Jacobson and Jerzy Kowalski-Glikman. Both have solid integrity, neither show any interest in publicity, both are clearly guided by genuinely serious scientific consideration. The cynicism of some of these comments is shameful.
If you want a good quick overview of the thermodynamics of geometry, read Jerzy K-G’s 5-page February 2010 note:
http://arxiv.org/abs/1002.1035
I think there is no better source if you want to know what is going on in that area. Among other things he offers specific fundamental degrees of freedom as called for in Verlinde’s heuristic.
It is appalling that people badmouth Verlinde’s paper merely because he does not offer specific tangible degrees of freedom to carry the temperature and entropy he talks about. His paper is a valuable and courageous opening game. Tangible details will be and already are forthcoming.
Peter,
What do you think about Padmanabhan’s line of research? (See summary, e.g., here). He has been working on a thermodynamical interpretation of gravity for quite some time now. Do you consider his line of research as dubious as Verlinde’s? If not, why? If yes, why?
Thanks.
Christine,
My interest in arguments about quantum gravity that say nothing about particle physics or unification has always been limited, so I haven’t followed closely research like Padmanabhan’s. He appears to be engaged in a serious investigation of some of the puzzles raised by the relation between thermodynamics and event horizons in GR, and that’s a perfectly legitimate area of research. His recent Verlinde-like claims to derive GR purely from considerations about entropy strike me as likely to be rather circular, or just dimensional analysis, but I haven’t looked into this carefully. In any case, just saying “gravity comes from entropy” seems to me a rather empty and useless statement. Unless you have some idea how to use this to say something new about physics, testable at least in principle, few people are going to be interested (unless you’re a well-known string theorist promoting the idea…).
Peter,
That seemed to be a qualitative work, and Verlinde did cite Jacobson in his paper, so this is not like he is coming from nowhere. The follow up papers did seem to get the idea and produce things with much higher quality of math. So, it doesn`t seem that the overly simplified approach from Verlinde was any kind of barrier to development.
And just to reinstate what I said before. This links of gravity to thermodynamics are not a new topic, rather, they are quite common and involve several hundreds of papers. Take a look at the cite count of Bousso`s papers and you will see the ones involving gravity, holography and thermodynamics approaching 500 citations, most of them by string theory, or sugra papers.
Speaking of simplicity, I downloaded his 1st paper on general covariant entropy the day it was out on arxiv and printed because it was extremely simple, and it was one of the very few things I could understand from arxiv.org, being on the 2nd semester of my course.
I guess what is catching people`s attention it is that this paper it is that this concept is starting to be widely cited used outside string theory.
“The important thing in science is not so much to obtain new facts as to discover new ways of thinking about them.” ~Sir William Bragg
If physicists were sophisticated enough to have a sophisticated vocabulary, like mathematicians, then it wouldn’t be a problem, bro. For example, if “conjecture” was required usage in the physical sciences, then people could conjecture all day long, and over a period of years the good conjectures would rise to the top.
As it is, you moron physicists use a binary vocabulary where everything is science of some sort (speculative, etc.), or it’s crackpottery. And we know why that is, don’t we? Because physicists are supposed to be smart like mathematicians, but yet the state of modern experiment for the glory physics doesn’t allow many conjectures to be fleshed out, thus no glory with a tight vocabulary, which is completely unacceptable for those seeking glory. Thus the loose definitions used.
But you’re not doing a thing to fix the fundamental problem, so keep on licking those big black boots to maintain establishment acceptability, and I’ll keep on doing the important things I do.
irt. the Bragg quote:
“you should keep an open mind, but not so open that your brain falls out” – Richard Dawkins.
I see several commenters rushing in to defend Verlinde’s paper, and for all I understand of those comments, they defend it because it’s a new approach.
As if that in itself is a justification. The plethora of “new approaches” is precisely the problem these days, because most of them are junk. If this one is new, why is it worth it? Does it explain some new and puzzling obervation?
Or if it’s not new, as references to similar and much older papers are present, then why the fuss?
And can anyone explain it to someone with an Engineering background like me?
(loose quote) “if you can’t explain it in an undergraduate-level course, then you don’t understand it” – Feynmann.