Why string theory is not science (Synopsis)

“As of now, string theorists have no explanation of why there are three large dimensions as well as time, and the other dimensions are microscopic. Proposals about that have been all over the map.” -Edward Witten

Earlier this month, a conference was held devoted to the question of whether untestable scientific ideas like string theory and the multiverse are actually science or not. While many opinions were stated and no one changed their mind, the answer is apparent: unless you’re willing to change the definition of science to include ‘this thing that isn’t science,’ then no, string theory is not science.

Image credit: Wikimedia Commons user Lunch, of a 2-D projection of a Calabi-Yau manifold, one popular method of compactifying the extra, unwanted dimensions of String Theory.

Image credit: Wikimedia Commons user Lunch, of a 2-D projection of a Calabi-Yau manifold, one popular method of compactifying the extra, unwanted dimensions of String Theory.

It’s a theory in the sense of a mathematical theory — like set theory, group theory or number theory — but it isn’t yet a scientific theory. Of course, it could become science, but that would require that it actually do the things a scientific theory does: make testable predictions that can be validated or falsified.

Image credit: public domain work by Wikimedia Commons user Rogilbert.

Image credit: public domain work by Wikimedia Commons user Rogilbert.

That’ll be a day we all greet with great joy. But until then, here’s why string theory is not science.

Comments

  1. #1 Wow
    December 23, 2015

    It;’s scientific, though. At the very least. Entirely possible it’s wrong, but that doesn’t mean not science.

    And a scientific theory? I still suggest yes, though this doesn’t necessarily make it *science*. As in a process you can *do*. Since there’s no testing or usable prediction to work off (yet), it isn’t science as the actions and activities of scientists. But it doesn’t preclude being a scientific theory.

    It is, however, scientific, in that it proposes and expresses the scientific method in its construction and formulation, and a theory in that it is a description of a basal option that elicits as a consequence the facts of multiple other scenarios.

  2. #2 The Peak Oil Poet
    New Zealand
    December 23, 2015
  3. #3 dean
    United States
    December 23, 2015

    Of course, it could become science, but that would require that it actually do the things a scientific theory does: make testable predictions that can be validated or falsified

    So, it is isn’t really considered science yet because there its practitioners have not come up with a prediction we can test. Since (I’m guessing, not sure) it isn’t possible to prove it CAN’T generate testable predictions, how long will the limbo last? That is, how long until “we don’t have the means to test these things now” becomes “these are not really testable?” And how, other than finding something explained by current theories that string theory can’t accommodate, will that decision be made?

  4. #4 Narad
    December 23, 2015

    That is, how long until “we don’t have the means to test these things now” becomes “these are not really testable?”

    That ship sailed with SUSY, hence the landscape, the multiverse, and the current last gasp of quantum gravity because string theory must still be the only game in town, or something.

    There’s a lot of great mathematics that has come out of it; physics, not so much (which is an understatement). You might want to check out Peter Woit’s joint* for a different take.

    * To avoid two-link automoderation, see also here:

    ht[]p://resonaances.blogspot.com/2015/04/what-if-part-1.html

  5. #5 Kevin
    December 24, 2015

    “The third prediction [the existence of supersymmetric particles] has come up empty, but we would need to achieve energies that are ~10^15 times higher than what the LHC can produce to rule out string theory entirely and falsify it.”

    This third prediction is, therefore, a falsifiable prediction. Our inability to perform the test, to *do* the science, does not mean it is not a science.

  6. #6 Wow
    December 24, 2015

    “So, it is isn’t really considered science yet because there its practitioners have not come up with a prediction we can test. ”

    Aye, it does appear to be a “power struggle” over experimental and theoretical scientists. I can agree there’s a difference between String Theory and Quantum Theory, and an *important* one.

  7. #7 Joseph
    December 24, 2015

    “As of now, string theorists have no explanation of why there are three large dimensions as well as time, and the other dimensions are microscopic. Proposals about that have been all over the map.” -Edward Witten

    Does the equation scream out anthropocentric? Why can’t we be the microscopic dimensions and part of the larger dimensions, just as the theory of branes suggests?

    Or better yet, why aren’t we smack in the Goldilocks middle, with a macroscopic three dimensions and a microscopic three dimensions?

  8. #8 Patrick Dennis
    Charlotte, NC
    December 24, 2015

    (Placeholder for Peak Oil Poet, who seems to have taken some time off from trolling Wow, possibly to get some well-earned sleep, then again maybe just to visit the loo.)

  9. #9 Ragtag Media
    December 24, 2015

    Perhaps string theory is not “Natural” Science.

  10. #10 Wow
    December 24, 2015

    Nice to see how “adult” is defined by some…

    the common thread seems to be that those with the least intelligence behind their claims and the most whining when they’re not accepted without question are the ones most likely to get together to dogpile like infants in a temper tantrum.

  11. #11 Wow
    December 24, 2015

    “Why can’t we be the microscopic dimensions and part of the larger dimensions, just as the theory of branes suggests?”

    Because branes don’t suggest we are that.

    The bit that is anthropogenic is the attempt to find an explanation we can understand that still accords with reality.

  12. #12 Yoda
    USA
    December 24, 2015

    Refusing to turn off Adblocker, I am. Missing All of Ethan’s wonderful posts, I do. There is no try. Only skip. (sigh)

  13. #13 Frank
    December 24, 2015

    I agree that untestable theories should not be official part of physics. Imagine that if physics is redefined to include them countless crackpots would start suing universities in the future to get their theories included in the teaching.

    I think the big question is, teaching of string theory, awarding degrees for it, employing professors for it, should continue or not?

  14. #14 PJ
    Perth, west Oz
    December 24, 2015

    Hey, yoda, turn ABP off, go into site, turn ABP on immediately; no hassles.

  15. #15 Sinisa Lazarek
    December 25, 2015

    String Theory IMO should just be renamed to String Framework and I think we would be fine. Because it is more of a framework then a theory. It’s a framework built around a notion that “things” are oscilating strings… and then it tries to build a model of reality. It doesn’t give predictions, nor is it testable still.. so not a theory. But a set of premises and tools that allow you to try and build a working theory.

    Maybe a bad parallel.. but in a way same as if GR was stuck at just spacetime is a thing that has changing properties, and it has a geometry… don’t know how to test it or how to calculate things from it… but it’s a start. That’s where I see string theory… if it’s right or wrong is a different matter altogether.

  16. #16 dean
    United States
    December 25, 2015

    I think the big question is, teaching of string theory, awarding degrees for it, employing professors for it, should continue or not?

    I would say yes (I think/hope most people here would). More importantly, I would the answer should be left to the physics communities, not to outsiders.

    I don’t see your “crackpots suing to get their theories included” being a thing at all.

  17. #17 Wow
    December 25, 2015

    “teaching of string theory”

    Where is it being taught? If it’s being taught to people who know how little verification there is of it as an option of what is thought as possibly correct, there isn’t much problem, is there?

    So how much it matters depends on how it’s being taught.

  18. #18 See Noevo
    December 25, 2015

    Ethan,

    Is Multiverse Theory also not science?

  19. #19 Narad
    December 25, 2015

    Is Multiverse Theory [sic] also not science?

    Perhaps if you did more than hit-and-run trolling, you would have noticed that this stale line of yours has been responded to before.

  20. #20 dean
    United States
    December 26, 2015

    you would have noticed that this stale line of yours has been responded to before.

    Not true. On a recent post by Greg Laden sn asked a question three times – the answer was clearly stated in the post, and he was told to “read the post”. He never did, and finally had the answer explained twice – he then proceeded to misrepresent it and imply it wasn’t a valid answer.

    There is no hope for a person as intentionally uninformed and dishonest as sn.

  21. #21 eric
    December 28, 2015

    Joseph @7: AIUI the ‘compact’ dimensions in string theory are considered that because they have a very high curvature. The three dimensions we observe directly do not have a high curvature and therefore aren’t in the ‘compacted’ class.

    Sinisa @15: String Theory IMO should just be renamed to String Framework and I think we would be fine. Yeah I mostly agree. The people working on it are more correctly doing ‘hypothesis development and comparative evaluation,’ not ‘theory testing.’ But hypothesis development and evaluation is also part of science (IMO).

    Dean @16: I would the answer should be left to the physics communities, not to outsiders. Yes I agree here too. In general scientists are pretty pragmatic about such philosophical questions. If we can’t award grants to empirically test ideas because none of the ideas in a field can be tested at this point, then we’ll award grants to people to come up with test ideas. And if we can’t do that, then we’ll award grants to people to develop testable variants of hypotheses or to evaluate hypotheses on other criteria. Science may have an ‘order of preference’ of things to do, with empirical testing being at the top of that order, but if we can’t do #1, we just simultaneously have some people think about ways to do #1 while the rest of us move on to priority #2. And so on down the line.

  22. #22 dean
    United States
    December 28, 2015

    eric, I agree with you about the the decision about teaching string theory, and go a little further: my larger concern centers on letting people outside academics make decisions about which things should and should not be taught in any discipline. We’ve already seen sn (long lasting troll and science denier) say no money should be spent on studying anything unless there is an immediate application – that studying something simply to learn is not a god thing. That approach – the foolish view of education as simply another business leading to the application of business philosophy to it and so destroying it, is the larger danger.

  23. #23 eric
    December 28, 2015

    That approach – the foolish view of education as simply another business leading to the application of business philosophy to it and so destroying it, is the larger danger.

    SN is a creationist, not some sort of business-oriented pragmatist. He opposes basic research because of religious ideology and don’t let his talk fool you otherwise. Pharmaceutical companies put a much higher % of their R&D budget into basic research than the government does (I’m going by memory here, but IIRC the numbers are something like 18% vs. 4%). Real business-oriented pragmatists generally recognize the value of basic, long-term-payoff research, and they’ll do it/support it as long as they think they’ll be around long enough to benefit from it. That doesn’t mean every industry will pump 18% of development funds into basic research, because some corporate outfits need to focus on short term profits in order to survive. But when a technical corporation can afford to make long term research investments, they generally do so.

    Knownothnigs like SN do not accurately reflect business interests. They do not accurately reflect how venture capitalists think. They are actually opposing sound business practices, not promoting them as they may imply. But that fact is irrelevant to SN; he would oppose evolutionary science due to religious reasons, even if he could be convinced of its contributions to industry and human prosperity.

  24. #24 dean
    December 28, 2015

    SN is a creationist, not some sort of business-oriented pragmatist.

    He is most certainly the worst form of creationist, but he does have a strong (in his opinion) argument for business-like approaches to everything, and that was the basis (he later said) for his anti-science post.
    I agree that he would not survive one class in any business program – certainly not in the quantitative classes we teach at the undergrad or graduate level, but that is due to his unwillingness to learn, not a lack of appreciation of business principles as he sees them.

  25. #25 PJ
    Perth, west Oz
    December 28, 2015

    Is it important to hilight someones (to you) shortcomings, or, rather, get on with the topic discussion? SN’s opinion is his alone, no matter what the bias – religious or otherwise. If we all thought the same, there would be no conversation to deal with, or think about. How boring that would be!

  26. #26 Narad
    December 28, 2015

    SN’s opinion is his alone, no matter what the bias – religious or otherwise. If we all thought the same, there would be no conversation to deal with, or think about. How boring that would be!

    He’s trolling. There is no “conversation” on offer to start with.

  27. #27 PJ
    Perth, west Oz
    December 29, 2015

    Hmmm. Trawling might have been a better word. Seems he has had a few good bites.

    🙂

  28. #28 dean
    December 29, 2015

    Pj, you need to examine more of sn’s “comments”. They are not opinions, they are intentional misrepresentations, willful distortions, and blatant lies. Whether it is “nothing should be studied unless there is an immediate application”, or his most recent statement about evolution where he states it isn’t science and says “you need to provide a mechanism showing how a fruit fly can change into, say, a fruit bat”, thinking he has anything that could develop into an intelligent conversation is a huge mistake. (and don’t get him started on how he is a better Catholic than the current Pope and would love to talk to him and set him straight on Catholicism.)

  29. #29 eric
    December 29, 2015

    PJ @25 – I was attempting to make a substantive point, not simply bash a troll. To tie my point into the main topic; an “application of business philosophy” would not rule out R&D in subjects like string theory, either. Ethan compares it to a mathematical theory. Well, wall street finds mathematicians and research into mathematics extremely useful. They aren’t the only ones; many other disciplines (including science) are “consumers” of mathematical advancements and development. Now whether a particular business would fund this particular work (string theory) is an open question – the devil is in the details, certain not every business will be interested in research in every mathematical subject. String theory is esoteric enough that the answer is very likely “no” in most cases. But the major takeaway here is that the characterization “this R&D isn’t science, it’s math” should in no way be taken to imply either (1) it won’t be useful to humans, or (2) its not a good long-term investment by for-profit companies. (1) is probably wrong most of the time, and (2) is probably wrong at least some of the time.

  30. #30 PJ
    Perth, west Oz
    December 29, 2015

    I take your points. I have read nearly all comments from most contributors over the past few years.I have a good idea of the trollers & trawlers. I find it easier not to bother stirring the pot up any more than some others delve in. Ignoring, rather than acknowledgement save a lot of dross to wade through to get to the higher quality offerings.
    These people tend to drop out over time when left out in the cold.
    🙂

  31. #31 The Peak Oil Poet
    New Zealand
    December 29, 2015

    hey, you folks, this chap is like the ultimately good hearted man.

    https://givealittle.co.nz/cause/scootermantimaru

    much appreciated

    (sorry for spamming, but it’s a good cause)

    pop

  32. #32 Wow
    December 30, 2015

    No, you’re not sorry. At all.

    And what good cause? There’s thousands of them. Every other one at least says when they pitch their sales line what the cause *is*.

  33. #33 The Peak Oil Poet
    New Zealand
    December 30, 2015

    never mind wow, your generosity is not needed. The crowdfunding target to get Scooterman a replacement mobility scooter has been met thanks to mostly local support.

    He’s the fellow that inspired me to love electronics through ham radio

    lovely man

    http://www.stuff.co.nz/timaru-herald/news/75513385/Community-help-means-Timaru-superhero-nearing-scooter-target

  34. #34 Wow
    December 31, 2015

    So it wasn’t needed, it wasn’t anything that others here would be in any way connected to, it’s not a genuinely tragic incident, and was only concerning to locals such as yourself.

    Why?

    Ah, forget it. The basic point is that if you’d said it was to find money to get some local dude a new scooter because he’s called scooterman but doesn’t have a scooter (I assume it’s a disability thing, otherwise it would be tres stupid otherwise), then those who find that story worthwhile would have been incentivised to look and donate, whilst those to whom that scenario isn’t worth the money that would go, for example, to their local hospice care centre would not have wasted time clicking on a link to some unknown site in this age of malware laden ginning sites.

    That scenario would have been much more worthwhile, and could easily have been done instead of fake concern over spamming.

    When you make a post, try to make available why anyone should give a shit.

    It really does help everyone and costs you nothing at all.

  35. #35 Rafael Bernal
    Mexico
    December 31, 2015

    One of the clearest articles I’ve seen explaining how a scientific theory is different from a mathematical one. I’ve always argued that the string theorists are mathematical mavericks, but all the math in the world makes no science!
    We could ask, Where is the beef? (In this case the experimental / empirical proof?

  36. #36 Chris Mannering
    December 31, 2015

    Some of you appear to be incontinent with your endless back-and-forth. It ain’t sexy to need a nappy.

  37. #37 Mark Thomas
    January 1, 2016

    As a layman my understanding is that string theory (superstring theory) describes physics near the Planck energies and it is not surprising that connections to the effective low-energy fields of the Standard Model have not been substantiated in our current era. Currently, the LHC physics or just physics as we know it requires that particle masses behave as point geometries until we break the points apart and reveal more fundamental constiuents and then we describe entities such as protons or neutrons containing condensates or fields (sometimes the word bag model is used). So some of this is semantics. Particles are obviously not point singularities and it is obvious that particles have harmonics attributable to them. The fact is that Planck physics is being probed by usage of the string theory and maths and the problem is trying to connect that which is the origin of things to a large vacuum bubble (our Universe) which is basically the Standard Model plus General Relativity. So right now is a large Gap called the Hierarchal Gap whic generally seperates the two. People on one side believe that senses (or show me the data, empicrical miracle of everyday) totally lights the path forward in Science and the other side currently use a sense of vision inculcated in theory without substantial empirical backup. Too much hype and poplar press is subverting that some of these approaches are not science and many programs are not even mentioned like the Langlands program, the uncanny Moonshine Maths, CFTs and the CM of Class Field theory, which upon providing yourself with some of this other knowledge may lead you to believe that there really is something to string theory, That there is always negative press on the Science approaches will always be there and some of this will pass in time as the picture becomes bigger.

  38. #38 Narad
    January 1, 2016

    As a layman my understanding is that string theory (superstring theory) describes physics near the Planck energies….

    What string theory “is” depends quite a bit on who you ask – as you allude to at the end – but I suspect that this notion of “physics near the Planck” scale comes from the goalpost-moving that has accompanied the lack of any whiff of SUSY to appear at the LHC.

    Taken as 10- or 11-dimensional unification, string theory cannot meaningfully be said to “describe” any physics. One can say that the “string scale” is ~10¹⁷ GeV, but you still need at the very least to reproduce what is already known, viz., a low-energy effective field theory. This comes way before the hierarchy problem. And there’s no reason to choose any particular model that meets this minimal standard unless it can connect with experiment. Worse, string phenomenology hasn’t even reached the first part yet.

    Returning to your list at the end, of course there’s really “something to string theory”; the AdS/CFT correspondence isn’t exactly chopped liver. The question is whether that something is “physics.”

    In related news, Luboš is so excited about the 750 GeV bump that he’s offering 1-to-10 odds. I wonder whether there’s Bayesian wagering advice for such cases.

  39. #39 Narad
    January 2, 2016

    ^ I should say that that Luboš entry is quite good,* including linking to Jester’s take. I’m not quite sure, though, whether the humor of comparing the subhed with the wager was intended or not.

    * See the one-off archetypology in comment 4 (the obfuscated one).

  40. #40 Narad
    January 2, 2016

    ^^ Dammit. “[R]eached the first part yet, as far as I know.”

  41. #41 Wow
    January 2, 2016

    “but I suspect that this notion of “physics near the Planck” scale comes from the goalpost-moving that has accompanied the lack of any whiff of SUSY to appear at the LHC.”

    Almost definitely not. At least not so far as the general consensus goes, though you obviously do, despite not thinking there is anything to string theory, given your wording used here.

    String theory explains the planck length and only explains things “more accurately” (if it IS accurate and correct) at the planck scales because it is a vibration on a string and we have well defined mathematical axioms about waves that indicate the vital indeterminacy of any measurement of waves.

    And all theories must reduce to the classical limit if they can be applied to a classical state, because all theories must explain the macro scale where the rules of classical mechanics were extracted as valid to the measurement of the time.

    And that last bit is why to claim it is only scientific if it’s measureable is problematic.

    Classical mechanics would be unscientific if we have measurements accurate enough to determine their departure from the classical assumption, but scientific if we do not have that level of accuracy.

    We only “know” that GR is scientific as long as we can’t measure the gravitational field inside an atom. We can’t (or at least haven’t) measured any gravitational waves. Does that mean GR is not scientific?

    But as for string theory, it explains, if accurate, the reason for planck uncertainty and holds most accurately at planck scales, hence “the assertion of a layman” you commented there.

  42. #42 Torbjörn Larsson
    January 13, 2016

    Odd how polarizing this issue is. Often people try to claim that string theory isn’t testable despite it has been tested at least thrice. Or they try to do what is claimed here, the way people are trying to turn it into not science is  by redefining what “science” is, to claim that a theory has to make unique predictions to be in the competition and then disregard that it has done so.

    It is really simple. String theory in the physical model sense has been tested at least twice. It was discovered when it made the then unique prediction of flux tubes among strongly interacting particles 1972 IIRC. That was replaced by a simpler theory the year after. It has also reproduced gravitons and the entropy-area prediction of black holes, derived by other means, which so far are theoretical consistency tests. So by the idea that theories are testable, make unique predictions, are useful, compete with other theories, et cetera, string theory has long been a theory.

    It isn’t a very competitive theory however. Mainly because it is predicting exotic physics. So who cares? I care more about the science process, and trying to make string theory out for something it isn’t (a pure mathematical theory) is problematic.

New comments have been disabled.