Wednesday, May 15, 2013 ... Deutsch/Español/Related posts from blogosphere

Richard Dawid: String Theory and the Scientific Method

Richard Dawid is a philosopher of science who was trained as a high-energy theoretical physicist and his new book that you may pre-order – it will be released at the end of June – isn't another addition to the rants by endless rows of populist crackpots, jerks, and imbeciles who try to criticize string theory without a glimpse of a rational justification (those extraordinarily stupid and dishonest books peaked about 7 years ago).

Instead, it is a philosopher's attempt to identify and localize, name, summarize, articulate, and present the reasons why string theory could have become the definition of status quo in the state-of-the-art theoretical physics despite the fact that the most natural conditions that string theory has something "new and direct" to say about seem to be inaccessible far from the currently doable experiments.

For this reason and others, the book was endorsed by big shots such as John Schwarz and David Gross.

The expensive yet short, 210-page-long book is divided to 7 chapters. The first one is an extended introduction to string theory (technical; sociology of non-experts talking about string theory; three contextual arguments in favor of ST); the second one is on the general conceptual framework of physical theories; next one on underdetermination applied to string theory (including some Bayesian reasoning); dynamics in high-energy physics; underdetermination in physics and beyond; whether or not one may claim that ST is a final theory; changes proposed for "scientific realism".

In the segments about sociology, the author describes both the near-certainty of the practitioners about string theory's validity; as well as the cynicism by many of the non-experts. The more stupid and ignorant you are, the more cynical about string theory – the unifying pillar of the 21st century physics – you may become. The cynics appear in various adjacent, next-to-adjacent, and unrelated disciplines – despite the fact that, as Dawid points out, string theory has helped to transform the way how people think and talk about pretty much all of theoretical physics and all of high-energy physics.

The three reasons behind the near-certainty about the theory's validity are:

  • the non-existence of alternatives
  • the surprising emergence of coherent explanations within string theory
  • extrapolation of the previous successes in high-energy physics: the Standard Model was also conceived because of largely theoretical reasons, had no alternatives, led to a nontrivial, surprisingly consistent unification of our descriptions of many things, and therefore had to be right
Concerning the first argument, it is the actual explanation why the top bright theoretical physicists focus this high percentage of their intellectual skills on string theory. They simply divide their mental powers to all promising ideas, with the weight given by the degree to which they are promising. Because one may approximately say that there aren't any other promising "big ideas" outside string theory, people can't work on them.

It is easy to misunderstand – and deliberately obfuscate – these facts. There exist "trademarks" that are marketed as competitors of string theory. But nothing really works over there. There exist no signs that these theories are on the right track. The people associated with these directions know that but some of them try to mislead the laymen about these facts. Some of them simply want to help themselves personally; others may be less egotist but they want a "greater diversity of ideas" than what the available evidence suggests as the right degree of diversity. And yet another group is just incompetent.

Concerning the second argument, it is a theoretical argument but a very powerful one. If string theory were a wrong theory of Nature, one would have no explanation why it has taught us about so many mechanisms that unify previously different concepts in physics and that retain their complete consistency, despite all kinds of a diseases that would have surely killed a generic wrong theory many times. The deep association between string theory and the laws that everything in the Universe obeys seems to be the only explanation of this coherence and unifying power, the ability to produce unexpected links, relationships, and transitions while avoiding any inconsistency.

Of course, one could argue that string theory is this coherent, powerful, and "willing to teach us" because of a different reason: it could be just a coherent mathematical structure that doesn't form the skeleton of the foundations of physics. If you wish, it could be the Devil who is constantly tempting us rather than God. But such an alternative theory would apparently predict that there will already be a demonstrable incompatibility between the highly constraining principles of string theory and some of the numerous (understatement!) insights we have already learned about the physical Universe. There aren't any inconsistencies of this kind, either: at least as the first sketch, string theory agrees with all the general features (types of fields and interactions etc.) we know from particle physics and cosmology. There's a lot of evidence that string theory is both very deep and very physical.

The last argument is probably a good way to describe the actual reason why I disagree with the suggestions elsewhere in the book that one needs to redefine the scientific method or do similar things. It seems obvious to me that the reasons that make string theorists near-certain that string theory is the right description of Nature have been used by physicists at least for 50 years and, in some respects, much longer than that.

Around 1974, string theory was identified as a candidate theory of quantum gravity – the only consistent one in \(d=4\) or higher so far. This already implies that its characteristic effects in which it shows its muscles in their full glory can't be directly measured in the experiments (already Max Planck was able to calculate that the Planck length was \(10^{-35}\) meters or so). I knew this was almost certainly the case when I was 10 years old or so. This inaccessibility by direct experiments is a defining feature of any theory of quantum gravity. Despite this knowledge, I wasn't repelled by string theory. If we can't "touch" something, it doesn't mean that we can't scientifically study it. Atoms became a part of science well before people "saw" them (because of the mixing ratios in chemistry and many other reasons). Physics of the 20th century brought us many more examples like that. Physics is really working like that most of the time today! When I was 10, I didn't know that almost 30 years later, a new kind of Inquisition would hysterically try to prevent people from applying the scientific method to energy scales that can't be directly tested.

String theory is really using the same kind of thinking about the possible deeper levels of explanation that were employed – and turned out to be successful – in the advances associated with quantum field theory. Any criticism of these argumentative patterns seems totally unjustifiable to me: it's really the only way how to think about these matters scientifically. The only plausible alternative is not to think about the unification in physics and the fundamental scale at all. I just think that the mankind would become a horde of uncultural barbarian apes if it decided it doesn't want to think about these issues – if it wanted to prevent a fraction of its intellectual resources from thinking about these fundamental issues.

Some people love revolutions and permanent revolutions. Am I among them? It depends on what you mean a revolution. I surely oppose any attempt to replace rational arguments in science by irrational ones (e.g. ad hominem ones or slogans that have nothing to do with the actual technical research); or to "ban" any kind of an argument that is obviously rational. Every solid enough argument and line of reasoning or inference, however indirect, should be used when we are forming our opinions about scientific questions. When this is done correctly in the case of fundamental physics, we reach a near-certainty that string theory is a valid (and probably the final) theory of Nature. It's possible despite the experimental inaccessibility of the Planck scale because direct experiments are very far from being the only tool how we are learning the truth about physics in the 20th and 21st century.

If you prefer the cheaper books by crackpots, you may buy books by Faggott (early August) and Unzicker (late July) instead.

Add to Digg this Add to reddit

snail feedback (27) :

reader George Christodoulides said...

his first and second arguments can be used about the existence of God.

reader Vladimir Kalitvianski said...

A "greater diversity of ideas" should not only be allowed, but also funded, which is rarely the case, unfortunately. Funding is crucial.

reader Luboš Motl said...

The only problem is that both arguments are wrong for God. It or He or She is extraordinarily non-unique, as the huge diversity of religions and subreligions indicates, and its proposed explanations are unusually incoherent, inconsistent, and they're never new - instead, they're (pretty much by purpose) predetermined dogmas that aren't allowed to be revised.

reader Luboš Motl said...

It's not the purpose of science to be "diverse". The purpose of science is to collect the evidence in order to learn the truth. If the evidence shows that the diversity of certain things or ideas in Nature is small or smaller than XY, then science shows that it's small or smaller than XY, and funding different answers that the evidence shows is fraudulent.

reader Dilaton said...

Ha, now Richard Dawid seems to be the second philosopher I actually like, after the one who showed that and how the "no alternative argument" works mathematically :-D

Crackpots, sourballs, and trolls have often no clue about the scientific method and they dont (want to) know or aknowledge the difference between direct measurements and equaly good indirect hints for a theory being implemented in nature ...

Just recently, I stumbled upon (I dont know what I was doing :-P) a looking from afar fun paper relating ST and nonequilibrium statistics :-)

This new link looks cool, what do you think about this?

Anyway, thanks for this nice book review, I like it :-)


reader Vladimir Kalitvianski said...

Lobosh, it is not "science" who makes the decision, but people. So it is highly subjected to preferences and prejudices. Watch what Feynman says about it (from t=1:05:45 to the end).

reader Luboš Motl said...

Dear annoying crackpot, could you please at least try to spell my name if you want to discuss what is science?

In science, it's always the evidence that decides. It's an impersonal process.

reader Dilaton said...

Science is about objectively learning how things work, not maximizing the diverstity!

Maximizing the entropy can be usfule in science ;-), but maximizing the diversity is rather appropriate in things like arts, music, etc... which try to serve as many people as possible and make them happy...

reader Vladimir Kalitvianski said...

Sorry for misspelling your name, it's a typo, nothing intentional.

So you say "Concerning the first argument, it is the actual explanation why the top
bright theoretical physicists focus this high percentage of their
intellectual skills on string theory." You present it as if there was a proof of bright theoretical physicists being never wrong. Prove it as a theorem then ("bright is right").

reader RAF III said...

"That's the great thing about science - there is no one right answer".
The words of Zach from TBBT always calm me at times like these.

reader Vladimir Kalitvianski said...

So what did you learn from the science history? Haven't you noticed the fruitfulness of diversity of approaches and lack of final answer?

reader Trimok said...

Wouldn't it be preferable to use a deductive logic to get some confidence in a theory?
Let's try with a quantum gravity theory :

From Qantum Field Theory, we know that vacuum energies are positive for bosonic d.o.f (degrees of freedom). and negative for fermionic d.o.f. If we include gravitation, this means that bosonic d.o.f. must equal fermionic d.o.f. (this is needed to avoid that vacuum curves space-time). The simplest solution is supersymmetry.

Because we include gravitation, we need supergravity.

Then QFT tells us that 2-spin is the maximum spin for interacting theories at large distance, and this gives 11 as the maximal space-time dimension for supergravity (and in fact, this theory exists).

So a correct quantum gravity theory should have a 11-D supergravity theory as a particular case.

And this is the case with M-Theory.

reader Vladimir Kalitvianski said...

"Throughout the previous history, there hadn't been any final answer to speak of but it was always important not to destroy."

I can't agree with you more!

reader David Nataf said...

There are a lot of "arguments" that string theory is untestable, which are replied to by counterarguments that it doesn't need to be testable.

I'm not even sure that is the right counterattack. It's not clear (is it?) that string theory is permanently untestable, it may just be too complex for humanity to have sufficient understanding to design coherent tests to gauge its effectiveness at this time. We're doing all sorts of spectacular things these days, we're mapping orbits around black holes and (almost) detecting gravity waves, measuring the Higgs mass, possibly measuring the dark matter particle, constraining inflation, constraining dark energy's equation of state, etc; it will take a while for us to have an understanding of these things competently never mind coherently.

Anti-theory arguments often point out that Einstein solved SR a few years after completing his PhD. However, that's the wrong interpretation imo. I'd say he spelled out SR ~50 years after Maxwell realized that electromagnetic waves travel with speec c.

The real bankruptcy of science is coming from people who want to hover over those actually doing work with a stopwatch, so that they can say "time's up" if no results come in within a certain amount of time. This kind of tyranny discourages ambition, it encourages people to do more trivial things, to repeat them ad nauseum, which actually adds more noise than signal to science. We need bright people to take on hard problems and to take their time studying them.

reader Dilaton said...

Slightly off topic:

Duh, I dont know why Sabine Hossenfelder is supporting this sourball proposal,

that will rather add to the bullying of fundamental physics (like quantum gravity she is herself working on I thought ?) in the popular media ... ?!

reader cedric bardot said...

I agree with you Lubos that Mankind needs to think about fundamental issues like the Planck scale despite its “inaccessibility by direct experiments” but can't we rely on brilliant phenomelogists and experimentalists to find out indirect ways to probe this scale (the CMB polarization spectrum is purported to give potentially a glimpse to physics at 10^16 GeV for instance)?

I like also very much your sentence: “Atoms became a part of science well before people "saw" them”. Thanks a lot to chemists from the XVIIIth and XIXth centuries! Then I wonder if some NMR spectroscopists from the XXth could not help physicists from the XXIst to build some mental picture or get a better intuition of the almost commutative geometry hiding behind the resilient spectral model (, an other quantum gravity or grand unified theory contender (supposedly different from string theory and that you reviewed in the past but not recently despite updatings like and …).

reader Eugene S said...

those extraordinarily stupid and dishonest books peaked about 7 years ago

For confirmation, look no further than Lubos' "canonical" Yay me!

If you prefer the cheaper books by crackpots, you may buy books by Faggott (early August) and Unzicker (late July) instead.

LOL. Our dear friend Unzicker doesn't know it yet, but he is about to be turned into a pinata on TRF :) This time, his publisher teamed him with a Canadian science writer name of Sheilla Jones; Google Books excerpt of a previous book by her. That should fix his atrocious English... but I doubt it will fix his intellect.

reader George Christodoulides said...

i didn't know about it. it's a good answer.

reader George Christodoulides said...

does anyone know other books besides not even wrong and the trouble with physics?

reader nabil ahmed said...

If you don't know string theory , You don't have any clear idea about how to describe the laws of physics beyond standard model . It's the only way we have to understand how to unify gravity with quantum theory . Otherwise , I think we will go nowhere . I've multitude of reasons why string theory is on the right track and all other approach are bound to failures . String theory is too big a step that I don't expect that we can find an experimental verification soon . We are talking about a theory of everything here so one should expect that it will be extremely hard at both the theoretical and experimental level . It's basic discribtion I believe will be a very non-inituitive and very hard to understand to scientists and un-understandable by the public so one should expect that the public will have negative attitude against it .

reader Shannon said...

I pray to closed strings gravitons :-)

reader Mitchell Porter said...

If you look at Minic's other recent papers (see end of the bibliography), you'll see they make repeated big claims about a new theory of time and a generalization of AdS/CFT. I don't think that part of it should be believed.

reader Dilaton said...

Thanks Mitchell, I am particularly interested in the AdS/noneqilibrium part of the paper (the relation between nonequilibrium physics and ST). Do you think that less ambitious idea is reliable?

reader Dmitry said...

Lubos, almost likely you're right and string theory will finally give us the answer. However string theory itself is based on some particular understanding of math, which hasn't been actually tested for being maybe not "correct" - obviously math as we know it IS correct, but at least "complete". We all start learning math so early in life, that basically we take a lot of things in form of "religion". For instance, the entire concept of "zero" is a sort of religion: you "must not divide by zero" - what is it if not a religion after all? "The most famous formula in a history of science" literally doesnt provide correct answer, until you make a notice that "the mass in the formula must be the rest mass". What is "the rest mass" textual line underneath om "m" in that famous formula? Is is still a part of "math", or something else? Or course, this formula also exist in complete form, where photon is also present. But what physics lies behind summarizing "massless and restless" part of the formula with the one that "has rest and has mass"? In terms of energy, they must both contribute of course. But is PLUS SIGN ITSELF a good model for description of something that is going on along with such contribution, where there are 2 parts, but "nevermind, they dont coexist at once"?
There could many reasonable questions like that about math that we learn at school. Starting from numbers! How do you know that numbers 1,2,3,4,5 and so forth give correct representation of anything that we've learned after so many years when such numbering system has been introduced? What did they count those days - fingers?? How could you be so sure that 11 dimensions that you derive from some fact or even simply conjecture, aren't there because of some fundamental flow in numbering system that was developed for counting fingers? Is there really 100% that such numbering could've been applicable for calculations over high energy particles and other stuff that's so far away from being seen by "finger counters"?
I could tell you that lately I was involved in some project that after 4 years of hard trying still didn't move on. What we finally did there that solved out the riddle in under 1 month, was CHANGING NUMBERING SYSTEM. We used a kind of {1.a.b}{2.c.d}{3.e.f} record system for numbering objects that we were dealing with, where each particular digit - in regular arabic numbering system - became something "3 dimentional". Literally, 3.14 became {3.0.0}.{1.0.0}{4.0.0}. Only we had real numbers that fitted our problem instead of zeroes there, otherwise we would't need any 3D numbers at all. And we haven't had fractions either, since our system was discrete: as likely is discrete everything else that we know. If so, where are all those fractions come from? Oh, it's obvious: basically from fingers :-). Are fingers still useful for high enery particles after all? Along with plus-minus signs? And calculus?... Really, really stupid questions, huh? But are you sure 100% that they are 100% stupid, or maybe only 99.99? Are you asking yourself questions like that before saying "the only candidate"?
Obviously, you're exceptionally smart guy Lubos, far exeeding anything average in a matter of your gift. With tremendous understanding of physics and math. But when you sound like "the only candidate therefore all the rest must die", you should know, that you are simply WASTING YOUR GIFT. And also, you make chances of turning a candidate into a winner much slimmer. Don't substitute a winning solution by cursing solution: in the last case the loser will be not only you personally, but also "the winning candidate". Which will be really unfortunate, especially knowing what's going on with science funding now

reader Mitchell Porter said...

If you check the bottom of page 18, you will see them saying that maybe their new idea for AdS/CFT justifies entropic gravity. That doesn't prove that the idea is wrong, of course! ... but it suggests that there is some wild speculation happening here.

reader Colin Wood said...

8 TeV nada zip, cue Johnny Mathis, Yes - It's over

reader Dmitry said...

I just had a minute to think of the
"Pi" concept. That “Pi”, which is used in almost any physical
formulae, and probably in all the most fundamental ones. Understanding that I
managed to establish about Pi was so strange, that I started checking
Wikipedia. And found there what I already expected to be found: "Pi IS NOT
PHYSICAL". Ha-ha for me, but how YOU guys tackle you problems, which
supposed to be purely physical, with something that IS NOT physical??? Isn’t
that obvious that the entire concept of “Pi” described in Wikipedia breaks down
at Plank scale? And also breaks down at (large) scales, which have a number of
different concepts of LARGE, capable of breaking Pi down? What’s going on with
you guys, how could you rely on “Pi”, dealing with a matter, which in such an
obvious way DEMANDS from you something more fundamental than Pi, that would fit
apparently THE SAME formulae, but in a PHYSICAL way?? No wonder you’ve spent
like 50 years already and “still trying”! Of course, you could keep on relying
on “no alternative”, but believe it or not, this is a good way to “keep on
trying” another 100 years

It’s very likely even from simply
healthy point of view that “string theory” found the right direction for its
approach. But if 50 years of trying aren’t enough for you, obviously you have
to re-think your approach, and start re-thinking FROM THE MOST BASIC LEVEL! Cancel
“make physics with no physics”! Question “Pi”, question “numbers”, question
calculus and algebra. Make them “physical”. Apparently THEN you’ll get back on
the right track and start DOING PHYSICS RELYING ON PHYSICS.

It’s a shame for Neil Degrasse Tyson to
be incapable of speaking with Brian Greene on appropriate for physicist – and also
for simply educated public - level. BUT EVEN A CARPENTER WOULD CHANGE HIS OWN WOODEN

So, maybe it’ll be useful for you to
think about yourself as of “a simple carpenter”: not as of some kind of “what I’m
saying has no alternative”-like man. Useful for both: you, and for the entire
science. Read literally – progress of the mankind, since exactly science is
responsible for the last thing. Hence only the smartest of all of us must do
science. Do it responsibly!

(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){ (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o), m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m) })(window,document,'script','//','ga'); ga('create', 'UA-1828728-1', 'auto'); ga('send', 'pageview');