New Year’s Multiverse

I see little to be hopeful about the new year, but had a glimmer of a hope that we’ll see a reduction in Multiverse Mania. Surely people will sooner or later get tired of stale pseudo-science. Just got back to work from vacation and it seems that so far this is not working out at all, quite the opposite.

At the yearly Edge question site, Martin Rees’s answer to the question “What scientific term or concept ought to be more widely known?” is The Multiverse, and he starts out with the usual sort of breathless hype:

An astonishing concept has entered mainstream cosmological thought…

Critics of the multiverse are described as having two arguments:

  • “Some claim that unobservable entities aren’t part of science.”
  • “Some physicists don’t like the multiverse: they’d be disappointed if some of the key numbers they are trying to explain turn out to be mere environmental contingencies governing our local space-time patch—no more truly “fundamental” than the parameters of the Earth’s orbit round the Sun.”

The first of these is the usual straw man argument, painting multiverse critics as too ignorant to realize that much of science is based upon indirect evidence, not direct observation. The actual argument of this sort against the multiverse is not that we can’t get direct evidence for it, but that there is no evidence of any kind for it, direct or indirect, and no plausible prospects of getting any. This case has been made ad nauseam here on this blog.

The second of these arguments is treated in much more detail in a new article at Nautilus by string theorist Tasneem Zehra Husain with the title Even Physicists Find the Multiverse Faintly Disturbing. Husain treats in detail the question of how physicists “feel” about the multiverse, and like Rees, makes the point that what physicists don’t “like” about the multiverse is that it removes hopes of being able to do things like understand the nature and strengths of fundamental forces, or calculate the masses of elementary particles.

Rees tells us that physicists are wrong to feel this way, that instead they should be awed by “the revelation that physical reality was grander and richer than hitherto envisioned” and that “If we’re in a multiverse, it would imply a fourth and grandest Copernican revolution.” Husain in the end seems to agree, quoting Gian Giudice:

Perhaps we need to let go of something we’re holding onto too tightly. Maybe we need to think bigger, refocus, regroup, reframe our questions to nature. The multiverse, he says, could open up “extremely satisfying, gratifying, and mind-opening possibilities.”

Of all the pro-multiverse arguments I heard, this is the one that appeals to me the most. In every scenario, for every physical system, we can pose infinitely many questions. We try to strip a problem back to the essentials and ask the most basic questions, but our intuition is built upon what came before, and it is entirely possible that we are drawing upon paradigms that are no longer relevant for the new realms we are trying to probe.

The multiverse is less like a closed door and more like a key. To me, the word is now tinged with promise and fraught with possibility. It seems no more wasteful than a bower full of roses.

Rees and Husain do a good job of showing that if science is about feelings, then Multiverse fans have a fine argument against critics arguing based on their negative feelings. The problem of course is that science is not about feelings but about evidence. The argument by critics that needs to be addressed is that there is no evidence at all for current multiverse scenarios, and no plausible way of getting any by scientific methods.

Nautilus has another multiverse-related piece just out, We Have Pushed Physics Too Far, by Marcelo Gleiser. My reading of the piece is that Gleiser agrees that the Multiverse is not successful science (“Parallel universes are a non-answer”), and I believe most physicists also agree. Unfortunately the lessons he draws from this (as I’m afraid many others are doing) is that the problem not a particular research program that failed (string theory, by ending up with the string landscape and the multiverse), but the whole idea of pursuing mathematical ideas about further unification:

We can call this the ultimate Platonic dream, the quest for a single simple and broad-ranging theory of physics. Indeed, during the past four decades, the search for such a theory has inspired many of the brightest physicists in the world. But today we are seeing the limits of this Platonic thrust to mathematize nature, due to a lack of experimental validation and several theoretical obstacles—including the possibility of multiple universes and the troubling questions they pose.

Gleiser sees successful physics as “an expression of intellectual humility”, with our current problem that of Icarus, trying to fly too close to the sun. I strongly disagree with him about this, seeing some of the best of physics as an expression of intellectual arrogance, not humility. It is intellectual arrogance that has gotten our understanding of nature as far as it has gone, and it will require intellectual arrogance to go farther. The current problem of theoretical physics is due not the sin of arrogance, but to a somewhat different one, that of refusing to admit error. Multiverse mania is largely about the refusal to admit that string theory unification is a failed idea. Yes, arrogance is one reason for this refusal, and admitting failure takes some humility. But then moving on to find different, more successful ideas will require a lot of both mathematics and intellectual arrogance.

Update: One more article at Nautilus about the multiverse. At least this one is explicitly theology, it explains:

a section of liturgy recited whenever we take the Torah out of the ark, and it’s related to a prayer that many Jews know, “Adon Olam.” The phrase is usually translated as “Sovereign of the Universe,” where the word olam can mean both “the universe” and “eternity,” expressing tremendous expanses of both space and time. But in this particular section of the Torah service, God is called “Adon Olamim,” where the suffix -im makes the word plural. This means that God is “Sovereign of the Universes,” as in, “more than one universe.” God doesn’t need to be a designer who had a specific plan in mind that led to the creation of humanity. God is, in fact, the Sovereign over all the universes, including the ones that don’t have life in them.

Update: Yet more explicit theological coverage of the Multiverse at science magazine Nautilus, with an article from Mary-Jane Rubinstein, a professor of religion, who is interested in multiverse versions of pantheism and explains:

As a professor of religious studies, I am particularly drawn to the places where religion and science seem antagonistic, but turn out to be entwined. The multiverse, I would argue, is one of those places.

My only disagreement here would be whether being a place where science and religion are intertwined is a good or bad thing…

Update: Yet more in the Nautilus series on the Multiverse: more theology, and now teleology.

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73 Responses to New Year’s Multiverse

  1. AcademicLurker says:

    vmarko,

    I’m not sure that “more is different” is in conflict with understanding phenomena through empirical scientific methods. After all, in P.W. Anderson’s famous article, he was talking about things like states of (bulk) matter, phase transitions, & etc. I’d say we understand a lot of those things pretty well.

  2. To echo AcademicLurker, vmarko makes it sound like condensed matter physicists are believers in the supernatural. I don’t think there’s anything at all contradictory between ideas of emergence (large-scale properties that are highly nonobvious can emerge from the collective response of comparatively simple underlying degrees of freedom interacting via simple rules) and scientific empiricism. It is sometimes a lament (see RB Laughlin’s first book) that emergent properties can make it difficult to access the underlying degrees of freedom, but that doesn’t mean giving up on experiment and observation.

  3. Low Math, Meekly Interacting says:

    Hopefully I’m not offending our host with off-topic nonsense…

    I love that Anderson article, but something about it makes me a bit queasy. He seems to be suggesting there’s a unifying law or laws governing emergent phenomena that make them amenable to some sort of generalized system of mathematical modeling, i.e. broadly predictable using maths that are substantially less complex than the phenomena being studied.

    I’m quite inclined to believe the notion that “more” is insurmountably “different”, in a way that will always make the laws of fundamental physics rather useless for describing many real-world phenomena. But I see no real-world evidence anywhere that would make me believe there’s some unifying mathematical law of emergence that will make disparate complex phenomena easier to comprehend, describe, or predict. Probably turbulence, high temp. superconductivity, and neurocognition have absolutely nothing to do with one another beyond involving aggregations of matter. I wouldn’t think it a good idea to advise someone looking to answer a big, fundamental question, to walk down a road that tries to “unify” these things.

    That’s not to say infusions of greater quantitative talent aren’t desperately needed in, for instance, the study of neurophysiology and consciousness. I just don’t think those disciplines will ever appeal to someone attracted finding deep, unifying mathematical laws that accurately describe reality. At least, they won’t appeal in anything remotely like the same way.

  4. Peter Woit says:

    Sorry, but enough about “more is different”. This is an interesting topic, but really has nothing at all to do with the topic of this posting.

  5. reader says:

    Peter Shor,
     
    These decades of effort were nearly all devoted to finding this deep structure using string theory. How do you know that the reason for the failure isn’t due to string theory rather than a multiverse?

     

    I disagree with “nearly all”, or what is more relevant, even if you take away all work on string theory that still leaves a vast number of physicist years devoted to this problem. Fortunately, working on a topic like quantum field theory has its own rich rewards even if it has not so far shed much light on why the seemingly arbitrary features of the Standard Model are as they are. I certainly don’t advocate ceasing to work on non-string related approaches to this issue, just pointing out that many have gone down this path before without success.

  6. AcademicLurker says:

    Peter,

    Apologies for the derail!

    More on-topic, since you’ve stated several times that trying to gain a deeper understanding of QFT would be a good place for more theorists to put their time and effort, here’s a question. When was the last period where you would say that fundamental advances in our understanding of QFT (as opposed to the standard model in particular) were taking place at a reasonable pace? Were the 70s that last golden era?

  7. Peter Woit says:

    Academic Lurker,

    There have been people working on QFT problems and making progress all the time, the problem has more been that the faddish nature of the field means that only a small number of possible directions are pursued by a significant number of people. In the late 80s to early 90s Witten’s discoveries about topological quantum field theories were a major advance, and work on those continues to this day. The AdS/CFT business starting in the late 90s and continuing to now also led to progress on understanding some QFTs. More recently, the work on the amplitudes has led to progress.

    I should stop going on about this and discourage others. This really is off-topic and deserves its own serious discussion in a better context.

  8. M Mahin says:

    See my post below on Husain’s post, entitled “Pretzel Logic of the Multiverse Fantasists.”

    http://futureandcosmos.blogspot.com/2017/01/pretzel-logic-of-multiverse-fantasists.html

    I discuss her strangest statement: “Logically speaking, an infinity of universes is simpler than a single universe would be—there is less to explain.”

  9. Maximillian G. Tresmond, Esq. says:

    Dr. Woit,

    As a non-physicist who regularly follows your site with interest, I have to ask: Why do credentialed scientists continue to to promote the multiverse “hypothesis” to the public when they know that the concept falls well outside the realm of legitimate science? The harm they are doing to the public understanding of science is likely to have a spillover effect to other branches which in turn could have a detrimental impact on public policy.

  10. Peter Woit says:

    Maximillian G. Tresmond, Esq.,

    One thing to keep in mind is that the physicists doing this are a small minority of the community. Another question to ask is why more physicists aren’t complaining publicly about what is going on.

    As for why certain physicists do this, I’m sure that they believe that there is something to multiverse explanations and that they are legitimate science (they do argue that this is legitimate science, although I disagree with their arguments). A less obvious reason is that the multiverse is a topic that easily lends itself to a popular exposition: there’s no significant difficult math or physics to explain, and people eat this up since it appears to be deep and mind-blowing, and they can kind of understand it. A physicist is a lot more likely to be asked to write a popular article or give a public talk about the multiverse than about ideas on, say, what the right variables are for computing scattering amplitudes (somehow Arkani-Hamed manages both, but he’s a singular point…).

    Finally, for some deeply devoted to string theory, they are torn between the multiverse being pseudo-science, and its providing them an explanation for the lack of predictivity of string theory. From them, one often hears “I don’t like the idea of the multiverse, but it may be true”.

  11. Tim Nguyen says:

    “But then moving on to find different, more successful ideas will require a lot of both mathematics and intellectual arrogance.”

    In my experience, another key problem is the lack of a fundamental symbiosis between math and fundamental physics. Sure, mathematicians will work on random math problems that physicists want to know the answer to (various knot/geometric invariants, etc.), but e.g. there isn’t a single math department to my knowledge that has a lattice gauge theorist (despite Yang-Mills being a Millennium problem). This gap just keeps getting worse since physics moves very fast with its loose standards of rigor, leaving mathematicians, who are grounded and systematic in the dark about what’s going on. On top of that, you have cultural issues – mathematicians who work on fundamental physics either aren’t “doing real math” (in the conservative eyes of mathematicians) or “doing what’s already well understood” (by the loose standards of physicists).

    Unfortunately, I don’t see a solution to this dilemma in the near future, which seems to be a prerequisite for needing more mathematical ideas (related to physics). There aren’t even enough mathematicians thinking about QFT, much less string theory or multi-versey things.

  12. Cosmonut says:

    Another remarkable aspect about multiverse mania is that this nonsense wouldn’t be tolerated in any other field.

    So suppose I claim I have an economic model which will exactly predict the price of potatoes tomorrow.
    Then I give a printout of a few million numbers and say:
    “Look one of these is the correct price, I just have no idea which one. And by the way, the other numbers are ALL correct as well – those are just the price of potatoes tomorrow in various parallel worlds somewhere.”
    I can’t see any circumstance where people will say “Hmm, he’s got a point” instead of dismissing my potato-price model as crackpottery.
    In fact, I will only make things worse for myself by getting all aggressive with “You can’t prove that my numbers are wrong, so I must be right !”, which is what string theory/multiverse champs seem to be doing.

    I suspect a part of the story is that popular books and media have convinced people that modern physics is all about “weird and wonderful” stuff. So, if you say something sufficiently weird, it must be wonderful as well. :/

  13. srp says:

    Very interesting point by Tim:

    “On top of that, you have cultural issues – mathematicians who work on fundamental physics either aren’t “doing real math” (in the conservative eyes of mathematicians) or “doing what’s already well understood” (by the loose standards of physicists).”

    In the past, private science funders (e.g. Rockefeller Foundation with Morgan and Pauling on biochemistry and molecular biology), targeted these kinds of gaps by giving money to people working the particular interdisciplinary gap they had identified. Maybe that’s where some of today’s big players (Templeton, Breakthrough) could funnel some resources.

  14. Peter Woit says:

    srp,

    The Simons Center at Stony Brook is doing exactly this.

    Again though, the math/physics interface is a topic of endless interest to me, but has nothing to do with the multiverse, so discussion of it best left to another posting.

  15. Tim Nguyen says:

    “The Simons Center at Stony Brook is doing exactly this.”

    I was one of the research assistant professors there and it was a great experience. However, proximity of mathematicians and physicists should not be confused with overcoming the cultural barriers mentioned above. And at the end of the day, one research center alone can’t change an entire cultural divide.

  16. chris says:

    reader,

    thanks a lot for the insight. I do not agree with your proability assignment, but I think I at least understand a bit how it comes about.

    Tim Nguyen,

    there are math departments that have lattice gauge theorists, especially in UK/ireland for historical reasons. There also are lattice people working on the millenium problem, but they are preciously few.

    I think the problem there is the same as almost everywhere: it’s not bread and butter physics that you can easily sell to your funding agencies. In our research environment, who is willing and able to work on a hard problem with small chances of success and who is going to finance it?

  17. Tim Nguyen says:

    Chris,

    That’s nice to know! I imagine you might be referring to places like DAMTP? I’d be really surprised though to find an ordinary pure math department with a lattice gauge theorist. Of course, the way in which science is currently funded (a whole other topic of discussion) only exacerbates cultural differences and only encourages people to do what’s normative and trendy in their field. If you don’t even have enough people working on/caring about pure Yang-Mills (which is just a tiny part of the Standard Model), you can’t really expect there to be any breakthrough mathematics in high energy physics. There was a time when mathematicians like Hilbert, von Neumann, and Weyl were doing math that was in tandem with deep and fundamental physics. Now mathematicians occur as citations and occasionally coauthors for physicists, rather than as leading figures.

  18. Jesper says:

    @ reader

    you write “Anti-multiversalists hold on to the hope that the Standard Model is actually much simpler because there is some deep structure there that we haven’t yet uncovered. Could be, but decades of effort devoted to finding this deep structure have so far yielded zilch.”

    Well, Connes and Chamseddine’s work/noncommutative geometry.

  19. anon says:

    I miss the days when science popularization meant Carl Sagan. I don’t even want to tell lay people I am a physicist anymore, since I am then invariably forced to discuss multiverses.

  20. Alan says:

    Thanks for the link to Professor Halvorsen’s piece you gave under “more theology” above. As he says, he is religious, so can anyone give me (degree level physics) any clues how this can fit into physics? I mean, where do we go with this, where do we start?

  21. Peter Woit says:

    Alan,
    Personally I don’t think theology has anything to do with physics. There’s an interesting sociological question of why some physicists have started engaging in theology, but I don’t think there’s a scientific question there.

  22. Alan says:

    Peter,
    Thanks for reply, but isn’t this (with respect) just the default position? Is there at least a way out of the problem he covers, as Halvorson sees this, by some input of philosophy at least. I mean, he sees a real problem. And I don’t mean to go on endlessly about this (!). His point is framed by his question … “why is it the case that it’s unlikely for an arbitrary universe to be conducive to life?”

  23. Peter Woit says:

    Alan,
    The problem is that this isn’t physics unless you have a testable scientific theory for what “an arbitrary universe” means. I’d claim there is currently no such thing.

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