Contested Boundaries

Apologies for too much recent posting here about the tired topic of the string wars. I hope to soon make amends by writing about something new I learned about geometric Langlands.

The summer 2015 issue of Perspectives in Science has an excellent article about the debate over string theory entitled Contested Boundaries: The String Theory Debates and Ideologies of Science (also available here), by Sophie Ritson and Kristian Camilleri. It deals with the debate from a point of view bringing together aspects of history, philosophy and sociology, while staying away from the technical aspects of the controversy.

The article has an interesting take on the debate, not taking sides as to who is right or wrong, but examining what the central issues have been and the ways people involved have chosen to make their case. One point made that I’d never thought of is that while this debate concerns an issue that comes up often, that of the boundary of what is science and what isn’t, here the usual roles are reversed:

In most scientific controversies in which we find scientists engaging in boundary work, the boundary dispute is generally over whether an unorthodox or minority view or approach should be regarded as science, pseudoscience, or pathological science. UFOology, parapsychology, intelligent design, and cold fusion all represent cases of this sort. The “ideological attempts to define science,” as Gieryn explains, are largely motivated by the desire “to justify and protect the authority of science by offering principled demarcations from poachers or impostors” (Gieryn 1999, p. 26). However, in the case of string theory, it is the dominant research program in a well-established field of science that has been forced to defend its credentials as “scientific” (Taylor 1996, pp. 177–9).

This presents an intriguing departure from most studied episodes of boundary work. String theory currently enjoys a privileged status by virtue of being the dominant paradigm within theoretical physics. Yet string theorists have found themselves forced to defend the scientific legitimacy of their research against charges that it has degenerated into a form of “metaphysics,” “non-science,” or “bad science.” In doing so, string theorists have attempted to “loosen” the methodological definition of science, while critics try to impose a stricter definition.

The emphasis of the article is on the string theory debate, not the multiverse, and I’m (accurately) quoted as defending string theory as “scientific”. When I wrote about this in my book back in 2002-3, I had no idea that multiverse pseudo-science would take hold among prominent theorists, a situation that raises issues I never thought would come up (the sort of thing Steinhardt is hoping for help with from the philosophers, see the last posting). The parts of the book about the “is it science?” question are ones I would write differently today, based on both recent history and new things I’ve learned about the philosophy of science.

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10 Responses to Contested Boundaries

  1. Andrew Norris says:

    Mention of boundaries brings to mind Turing’s view on them:
    “Science is a differential equation. Religion is a boundary condition”

  2. Jim Beyer says:

    This was covered at a basic level on NPR’s Science Friday:

    Should These Scientific Ideas Be Retired?

    I think it is significant (and troubling) because even Ufologists, etc. don’t dispute the validity of the scientific method; they just report results/findings which are not reproducible. I find John Mack more credible (as a researcher) than some string theorists….

  3. Marc says:

    Peter– you are quoted as saying “At the moment [string theory] is a theory which cannot be falsified by any conceivable experimental result.” Suppose the 100 TeV collider discovers extra dimensions — ten of them. Would the knowledge that space-time is at least fourteen-dimensional rule out superstring theory? Or, perhaps more reasonably, suppose extra Z’s are discovered that show that the gauge group of nature has at least rank 10 (or some large number). Would this rule out heterotic string theory? Yeah, these are extreme, and rather ridiculous, but they are “conceivable”…

  4. Peter Woit says:

    “conceivable” is perhaps an overly strong word, I think with that statement I was trying to be provocative, not precise. A better wording might have been “plausibly conceivable”. And I wasn’t just referring to heterotic string models, but to more general possibilities.

    But, honestly, it is extremely difficult to come up with actual experimental results that one couldn’t somehow explain by a complicated string theory model. First of all, the examples you give assume a certain theoretical interpretation of some experimental result, with experiment not directly measuring number of dimensions or rank of gauge group. Trying to think of experimental results that would have that interpretation, I suspect alternate explanations would be possible. Even given airtight evidence for one of those theoretical interpretations, it’s unclear to me that one really can’t find some kind of string model with those properties. For a while there was an active research program of trying to characterize the “swampland”, qft theories that could not come from string theory. Typically though, claims to identify such a QFT were quickly met by someone coming up with a string theory construction, see for example

    So, the claim I had in mind was really: think of anything you can plausibly imagine turning up in a plot from an LHC experiment in the next few years and find an example that would cause string theorists to abandon string theory. I can’t think of anything like that.

  5. Peter Woit says:

    After more thought, a quite precise version of the claim I had in mind that Marc refers to would be:
    “No one working on an LHC experiment has ever run a Monte-Carlo for some scenario, such that if data matched the Monte-Carlo, that would cause string theorists to abandon string theory.”

  6. Peter Woit says:

    Thanks. I’ve now put both links in the posting, hopefully people will be able to get access to one or the other of them.

  7. Anonyrat says:

    “No one working on an LHC experiment has ever run a Monte-Carlo for some scenario, such that if data matched the Monte-Carlo, that would cause string theorists to abandon string theory.”

    Much sharper, but could use further sharpening in my opinion. For instance, the string theorists’ riposte could be – “Nor have they run a Monte-Carlo that would cause physicists to abandon QFT. Abandon SUSY, the Standard Model, etc., yes, but not QFT”.

    I know you’ve previously dealt with this kind of objection, so just saying….

  8. Peter Woit says:


    I’m sure many if not most theorists would happily abandon the Standard Model given a proven violation of it, and much of the LHC effort is looking for that, surely with Monte-Carlo simulation of possibilities. In some sense LHC research is mainly an effort to falsify the SM, and my point was just that no one is even trying to falsify string theory.

    Better to not reopen the question of the appropriate definition of falsifiability though, it’s a thorny subject discussed here often, and it seems highly unlikely anyone will have anything new and insightful on the topic.

  9. al says:

    It’s a pity that Roger Penrose (Roads to Reality) is not mentioned.
    Also a glance towards the financial aspects might have been useful in discussing sociology: doing theoretical physics is the cheapest way to do (natural) science, and it’s a bonus if the work is never refuted. Advertising nowadays often promotes ‘prestige’ that is not to be judged by grossly material standards.

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