The Ultimate Guide to the Multiverse

Yet another cover story about the Multiverse can be found this week at New Scientist, which calls it The Ultimate Guide to the Multiverse. As just one more in a long line of such stories over the last decade, a trend that shows no signs of slowing down, one can be pretty sure that this is not yet the “ultimate” one, nor even the penultimate one.

The content is the usual: absolutely zero skepticism about the idea, and lots of outrageous hype from the usual suspects (Bousso, Tegmark, Susskind, etc.) We’re told that scientists are now performing tests of the idea, even at the LHC. The LHC test has been a great success: Laura Mersini-Houghton used the multiverse to predict that the LHC would not see supersymmetry, and that prediction has worked out very well so far. There’s a companion editorial Neutrinos and multiverses: a new cosmology beckons, which tells us that the multiverse is now orthodoxy, backed by “almost everything in modern physics”:

The widest crack of all concerns a theory once considered outlandish but now reluctantly accepted as the orthodoxy. Almost everything in modern physics, from standard cosmology and quantum mechanics to string theory, points to the existence of multiple universes – maybe 10500 of them, maybe an infinite number.

If our universe is just one of many, that solves the “fine-tuning” problem at a stroke: we find ourselves in a universe whose laws are compatible with life because it couldn’t be any other way. And that would just be the start of a multiverse-fuelled knowledge revolution…

These are exciting, possibly epoch-making, times.

This past week also saw the premiere of the Multiverse episode of Brian Greene’s Fabric of the Cosmos series on PBS. It’s more or less an hour-long infomercial for the Multiverse, with the argument against it pretty much restricted to some short grumpy comments by David Gross about how he didn’t like it. Brian’s pro-multiverse argument was that many new advances in physics are all pointing to a multiverse, and he showed support for the idea as resting on a three-legged structure. One of the legs was string theory, and I’ve described elsewhere recently how circular reasoning makes this one very shaky.

The multiverse propaganda machine has now been going full-blast for more than eight years, since at least 2003 or so, and I’m beginning to wonder “what’s next?”. Once your ideas about theoretical physics reach the point of having a theory that says nothing at all, there’s no way to take this any farther. You can debate the “measure problem” endlessly in academic journals, but the cover stories about how you have revolutionized physics can only go on so long before they reach their natural end of shelf-life. This has gone on longer than I’d ever have guessed, but surely it has to end sooner or later, and I have no idea what rough beast will slouch onto future covers of New Scientist and episodes of Nova a few years down the road.

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52 Responses to The Ultimate Guide to the Multiverse

  1. Quantumburrito says:

    I don’t think the multiverse will end any time soon since people will always be suckers for fairy tales.

  2. Peter Woit says:

    Quantumburrito,

    Yes, but even most children get bored if you keep telling them the same fairy tale every night, and sooner or later start demanding a new one.

  3. Chris Oakley says:

    It could be that Susskind, et al have been told the answers to the “ultimate questions” by a race of hyper-advanced aliens, but have also been told to keep it quiet or risk being annihilated. String theory, 11 dimensions, multiverses and all the other B.S. is just their way of throwing the rest of mankind off the scent.

  4. grant davis says:

    Well, as long as Ed Witten and all the best and brightest at the Institute for Advanced Study pursue and exalt the untestable String Theory, instead of speaking out against it, expect the multiverse mania to continue.

  5. Giotis says:

    Inflation is now part of Standard model of Cosmology (supported by an increasing corpus of evidence) and almost all models of inflation predict eternal inflation and thus the multiverse. Thus the multiverse stands on solid theoretical ground regardless if String theory is correct or not. String theory though gave a boost to the multiverse idea because String theorists are the dominant group of the top American Universities and these Universities more or less determine what is orthodoxy and what is not. So indeed in the last decade we had a paradigm shift.

  6. Beelzebud says:

    I started watching that Nova episode, and turned it off before it was over. When he starts going on about how there is an exact copy of himself in an alternate universe, it just made the whole thing too silly to even take seriously.

    I’m open to the idea of “pocket universes”, etc, but even if that’s the case I don’t see how anyone could draw the conclusion that they have copies of themselves in multiple universes. Is there some mathematics they are using to make this guess, because the show is so light on technical details I felt like a toddler he was talking to? Please tell me that these conclusion are arrived at based on something tangible. I just don’t see why the universe would be making exact copies of human beings, or anything else for that matter.

    It’s not hard to see why physics hasn’t gone anywhere in 20 years, after watching part of that episode. I’m not even sure if he talked about one thing that can be verified with observation or experiment. He might as well be trying to prove that the bible is true.

  7. aa says:

    almost all models of fairys include leperchauns.

  8. Aidyan says:

    I’m not particularly in love with multiverse theories, tend more to be an agnostic. However, as far as I could see from some papers there are ideas to test the hypothesis and something has been already done (see e.g. http://arxiv.org/abs/1012.1995). So far data seem to dismiss it, but I wouldn’t say that the theory is (or will forever) be impossible to test.

  9. Peter Woit says:

    Aidyan,

    I wrote extensively about that heavily-hyped “test” of the multiverse here

    http://www.math.columbia.edu/~woit/wordpress/?p=3879

  10. the aethereal multiverse says:

    Omitting the internet and blogs etc., the aether theory was taken very seriously (hyped?) by distinguished physicists at the turn of the 19-20th centuries. Sir Joseph Larmor, the Lucasian Professor of Mathematics who preceded Dirac, wrote a monograph “Aether and Matter” in 1900
    http://books.google.com/books/about/Aether_and_matter.html?id=jvZImrMMUcIC

    But in 1905 Einstein came along and offered an alternative explanation of the observed phenomena, viz. the (Special) Theory Of Relativity, which did not require the aether hypothesis for the propagation of electromagnetic waves. And as events proved, the theory of relativity could do a better job of explaining things than could the aether theory. The aether theory did not go away of its own accord. It went away only when something better came along. Furthermore the aether theory was never explicitly disproved. It was simply abandoned. But Larmor was not a fool; he is remembered today for Larmor precession, if nothing else.

    So today the multiverse is hyped, and there is tv and the internet etc. The multiverse is taken seriously by talented minds. It is also disbelieved by talented minds. But the ultimate arbiter will be the advent of an alternative theory, which can do a better job of explaining observed phenomena. Until that happens, the multiverse will not go away.

  11. grant davis says:

    dear aethereal multiverse,

    but the multiverse explains nothing and cannot be tested. thus some other theory cannot out-perform it in the realm of explaining nothing and untestability, unless it is also not science.

    there is no need, as you argue, to disprove non-science with science. simply put, the multiverse is not science. we do not need any additional science to somehow displace non-science. rather, the non-science of the multiverse ought be outed and then ignored because scientists are supposed to be moral, rational, logical, honest creatures.

    🙂

  12. Peter Woit says:

    the aethereal multiverse,

    I think there is a real danger that the people pushing the multiverse will be successful at what they’re trying to accomplish: getting people to give up on conventional scientific standards, and turning this into the new orthodoxy. One motivation for this is to avoid admitting the failure of string theory unification. If they’re successful, young people who enter the field will be taught that there’s no alternative to string theory unification, the problem has been solved by showing that it is inherently impossible to do better. As this becomes more and more entrenched the path for someone looking to do something better (and better than pseudo-science is not much..) becomes harder and harder. This is not like the beginning of the last century when there were a lot of experimental hints pointing in promising directions.

    Interestingly, despite his dedication to string theory, David Gross is someone who clearly finds this too high a price to pay, at least so far. The disturbing trend I see is more and more physicists who should know better falling into line here.

    But this is an argument about what the scientific orthodoxy will be. It may very well end up being the string theory multiverse. If so though, there are only so many years that science magazines can keep putting it on the cover as a new revolutionary idea. At some point there will have to be something new for the cover, and I’m wondering what it will be.

  13. Nathalie says:

    Dear aethereal multiverse,

    I can’t resist adding to your statement “Larmor was not a fool …” that moreover Larmor had Lorentz transformations before Lorentz and some physicists in Leiden, including Lorentz himself, knew that.

  14. Beelzebud says:

    the aethereal multiverse,

    “So today the multiverse is hyped, and there is tv and the internet etc. The multiverse is taken seriously by talented minds. It is also disbelieved by talented minds. But the ultimate arbiter will be the advent of an alternative theory, which can do a better job of explaining observed phenomena. Until that happens, the multiverse will not go away.”

    What observed phenomena does a multiverse hypothesis describe? Honest question. I’m by no means an expert.

  15. bcs says:

    It seems many distinguished theorists committed themselves to the multiverse idea. Some are willing to bet their house or dog’s life on it, some are only willing to bet his friend’s house and dog’s life. Whether they really believe it, or just try to find something to go beyond standard model… I don’t know.

    It is well known that some high-energy theorists consider condensed-matter physics probably not much better than chemistry, economics, or biology. There has been a long list of such people: Dirac (implicitly), Gell-mann, Pomeranchuk, etc. Of course, I myself don’t think so.

    However, at this particular juncture, I consider myself lucky that I can still do physics research the old honest way, guided by the experiments.

  16. Bernhard says:

    This was very depressing, as usual. I hope this will go away, I simply can´t believe HEP (and cosmology) are taking this course, we are risking going from respectful fundamental science to the laughable part of physics (if we already didn’t), a new astrology.

    My hope is that the at some point people will just stop funding this thing or at least to fund only exceptional cases. To make this mainstream is absurd. Pointless speculation after speculation, hype after hype these guys just won´t stop. At least it is clear the purpose they serve: show business and nothing at all to do with science or the truth. Makes me sick.

  17. Giotis says:

    Beelzebud

    It explains the observed value of the cosmological constant and in general why the universe seems fine tuned for life.

    There is no other explanation for that at the moment (and according to many there will never be one). The alternative is to believe in God…

  18. the aethereal multiverse says:

    Beelzebud – “What observed phenomena does a multiverse hypothesis describe?” None that I know of. The aether theory of 19C also failed to explain any observed phenomena. All attempts to detect the aether wind failed. (The Lorentz-Fitzgerald length contraction was born as an attempt to reconcile the null result of the Michelson-Morley experiment.) And yet the aether theory remained the orthodoxy.

    grant davis – “… because scientists are supposed to be moral, rational, logical, honest creatures.” That is the (Platonic?) ideal, which is clearly not happening, on a large scale. A lot of it has to do with lining one’s pocket with salaries.

    PW really hits the nail on the head (or punches the head on the nose, if you prefer) – “This is not like the beginning of the last century when there were a lot of experimental hints pointing in promising directions.” They key is *experimental hints*. That is the really lacking ingredient in these modern times. And that leads to the danger of a change (or corruption) of the scientific orthodoxy. But all of that will only change for the better when new data (BSM) comes along, and an alternative theory which can do a better job of explaining it.

  19. DB says:

    Until prominent physicists step into the limelight to ridicule and debunk these charlatans the situation will only deteriorate. The likes of Greene, Kaku et al. have free reign because they encounter precious little pushback from professionals of far greater eminence than they.
    There seems to be a culture of omerta, where one does not speak out against one’s “colleagues” in public. Dirty linen is to be washed only in private. The fear seems to be that such arguments aired in public would damage physics funding generally by creating the impression that physics was wracked by disagreement and division.
    From this perspective it seems that allowing the likes of Greene to peddle their nonsense is viewed as the lesser of two evils.

  20. a says:

    The problem is not the hype.
    The problem is that this anthropic stuff could be true.

    We should at least try to get some physics out of it, see e.g.

    http://arxiv.org/abs/1111.2551
    “Anthropic solution to the magnetic muon anomaly: the charged see-saw”

  21. Bernhard says:

    a,

    This paper assumes that “the only scalar existing at the weak scale is the Higgs” and that the explanation for this lies in anthropic reasoning.

    Even if I were to swallow the assumption for the sake of seeing what phenomenology comes out of it I absolutely not accept that the “explanation” for this should in any way be anthropic related.

  22. Aidyan says:

    Didn’t they tell us that the atomistic hypothesis is mere metaphysics since we won’t never have a microscope showing us atoms? (E. Mach) Who said that we will never be able to know the star’s chemistry because they are too far away? (A. Comte) And what about that famous guy who told us that he “never frames hypothesis” but now we know from his manuscripts that he did so continuously? I think that history has shown how rejecting too quickly a theory only on the assumption that it will never be testable or because too speculative (here multiverses) is not reasonable.

  23. Peter Woit says:

    Aidyan,

    I don’t think you can argue away multiverse arguments trivially as in “we’ll never observe other universes”, but if you look carefully at the multiverse arguments being made (see for instance the link I gave you earlier) you find that they are very weak, full of holes, and outrageously overhyped. Before going to magazines and TV to claim a new scientific orthodoxy, multiverse advocates should have something more solid than “it’s not impossible that someday we might somehow figure out how to get evidence for this, even though things don’t look promising right now”, which is where they are today.

  24. Aidyan says:

    Peter, ok this sounds better… 😉 As to the motives which stand behind the “outrageously overhyped” arguments I tend to subscribe to what Smolin describes in the (much less discussed and taken into consideration) last chapter of his book “the trouble with physics”. Just an excerpt (you certainly already know, but also for others):

    “Put simply, the physics community is structured in such a way that large research programs that promote themselves aggressively have an advantage over smaller programs that make more cautious claims. Therefore, young academic scientists [note: S. Feeney is a PhD student] have the best chance of succeeding if they impress older scientists with technically sweet solutions to long-standing problems posed by dominant research programs. To do the opposite – to think deeply and independently and try to formulate one’s own ideas – is a poor strategy for success. Physics thus finds itself unable to solve its key problems. It is time to reverse course – to encourage small, risky new research programs and discourage the entrenched approaches. We ought to be giving the advantage to the Einsteins – people who think for themselves and ignore the established ideas of powerful senior scientists.”

    Sorry, if I advertise another book… 😉 But in my opinion he got to the root of the problem, which is not scientific but political/ideologic/sociologic. As long as the (unwritten) rules on which the academic system is based will not change it will remain a pious illusion that these things can change either.

  25. Peter Woit says:

    Aidyan,

    What Smolin wrote applies well to the string theory story, but the multiverse one is much stranger. The multiverse remains quite unpopular among physics departments, with only a small number likely to hire someone working in this area (and lots of NSF panels likely to refuse to fund multiverse grant proposals). It seems to me that what is happening is that multiverse proponents are trying to do what string theorists used to accuse me of doing: going to the press and TV to try and win an argument they have lost with their colleagues. If they can get the public sphere to believe that this is now “scientific orthodoxy”, they may break down the unwillingness of physics departments to put up with this kind of pseudo-science. I suspect this isn’t going to work, that young multiversers will find that this is no way to get a permanent job. But, we’ll see, the campaign continues, with multiverse mania still dominating the media, and only David Gross willing to try and do battle on those grounds.

  26. pravda says:

    Look at the situation from the other point of view ~ what’s in it for anyone (including David Gross) to do battle with the multiversers? (or string theorists, or anyone else promoting hype …) Probably they just open themselves to a heap of abuse, and receive no real reward from “the establishment”. How many physics departments (or govt labs ~ Fermilab? CERN?) encourage their staff to make public statements against “people who promote hype”? “Standing up for scientific merit” isn’t exactly rewarded. Lots of people grumble about the hype, but to speak out is to label oneself as a troublemaker.

  27. Puzzled says:

    The “multiverse” PR campaign puzzles me, for a much simpler reason than most of the issues raised here… the issue is “what problem does it resolve?” I can’t see any problem for which “multiverse” provides an “aha” moment. Most truly powerful scientific or mathematical ideas create that sense of “now I get it” when something truly paradoxical suddenly makes sense.

    Maybe I misssed something in my 60 years of mathematical and scientific life that requires a multiverse (and/or the “anthropic” principles that beguile the media) to resolve. Otherwise, it’s another “just so” story – plausible, entertaining, and just clever enough to impress the rubes.

    While it’s kind of sad that these things sell books and get grants, science is really not defined by the well-funded and most visible. Intellectual integrity ultimately defines science for those who do science. The best and worst part of science is that anyone can say they are a scientist, but in the end, the “aha” is the only real measure of science. (not the “coolness factor” and the folks that go to the best parties).

  28. Einstein's Bastard Son says:

    String theory first started to enter the public consciousness in the mid 80s. Your book and Smolin’s weren’t published until 2006. So I’m guessing that this new multiuniverse craze might last at least 20 years.

  29. Einstein's Bastard Son says:

    *multiverse

  30. Bobito says:

    The “multiverse” is basically a religious argument.

    “God” is also a hypothesis that “explains” the observed character of the universe. Lack of explanatory power is not the reason that “God” is a bad answer to questions about the nature of the universe. Rather, it is a bad answer because such an explanation provides nothing, in operational terms, that was not available before.

    The “multiverse” as explained by many is not so different from “God”.

  31. John says:

    It is important to point the differences between the different kinds of multiverse, for example in this blog I have not seen a clear position respect to the work of David Deutsch on the quantum multiverse, Deutsch have two long books (one publish this year) and many papers on this subject but strangely there is not yet a post about this, I think this is a strange gap in the multiverse mania series. I think Deutsch ideas have not been consider seriously yet, mainly because ideas that include the word multiverse are rejected even before being considered, maybe would be useful to use constructions as strings-multiverse, inflation-multiverse, quantum multiverse to be more clear.

  32. Guillaume says:

    Yes, I’d be interested to hear what Peter thinks of Deutsch’s quantum multiverse too. I’ve already suggested that a while ago.

    Having skimmed through his latest book, my own opinion on that particular topic is that his version of the quantum multiverse requires an *uncountable infinity* of universes, and that’s just unphysical.

    I could say a lot more about his book, which contains some interesting stuff and a lot of outrageous crap, especially when he ventures out of pure science into the real of human affaires.

  33. besnard says:

    I find this multiverse bashing a bit sad. As Peter sais in response to Aydan, multiverse arguments are not trivially wrong. Generally speaking, a theory is not unscientific because it sounds crazy to some people. In fact, a single infinite universe already contains the same strange things as the multiverse. One has to remember also that most, if not all, physical theories make claims about entities that cannot be observed.

    Finally, I agree that the claim “there is a multiverse” is by itself impossible to disprove. But the situation is entirely different if a theory predicts A, B, C, and D : “there is a multiverse”, and A, B, C are usual falsifiable predictions. If it turns out that A, B, C are observed, then you have to believe in D until someone comes up with a better theory that explains A, B, C but does not imply D. The problem with multiverse hype is that there is at the moment no such a solid theory which happens to predict a multiverse (although I think a case could be made for eternal inflation).

    This is why I think critics should concentrate on the theories, and not on the multiverse idea per se.

  34. Peter Woit says:

    John and Guillaume,

    The “multiverse” of various interpretations of QM is a completely different issue than the string theory landscape pseudo-science one. In the QM case, you may be able to perfectly sensibly talk about a “multiverse”, but you can also describe exactly the same theory and same physics without invoking “other universes”. Because of this I confess to a distinct lack of interest in this kind of debate over interpretation of QM, it seems to me to just avoid the interesting issues in favor of empty arguments over language. So, I haven’t read Deutsch’s books and so don’t have anything to say about them. I did read a recent New Yorker profile of him and wrote a bit about it here:

    http://www.math.columbia.edu/~woit/wordpress/?p=3656

    My reaction there was that his argument that the existence of a quantum computer meant you had to have a multiverse didn’t make sense to me. This is still true, but, again, my main problem is that I’m not convinced it’s a non-empty issue worth thinking much about.

  35. SteveB says:

    One aspect of this problem is the economic one. There seem to be more new books being published than new, interesting and testable ideas. When a popular, well spoken physicist writes a new book they make the circuit of the radio shows (Fresh Aire, Science Friday, etc.), also the magazines, and eventually Nova TV. All of these need popularity to survive. Popularity is dependent on the public’s “gee whiz” factor — and in my opinion — more important than Science, truth, or usefulness.

    I found Greene’s Nova series to be totally lame, with no real content, but just cute. unnecessary CGI . What a waste of 4 hours of potential science programming. New scientist is producing more and more of these silly articles and they are always highlighted on the cover. Almost every week! What a waste! (We have heard from a NS contributor here before, maybe she will provide some inside info about what the heck is going on there.)

    Give me some dinosaurs or underwater archaeology anyday. I’d like some TV shows on new astronomical observations, on solid-state physics, on the electrical grid.

    These just don’t have the popularity for the American public who do believe fairy tales and vote for advowed anti-science candidates.

    Sad times….

  36. Beelzebud says:

    Giotis,

    That sounds an awful lot like just trading one myth for another one that you prefer more.

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  38. Trevor Turton says:

    Lots of good, strong comment here. Is the take-home message Multiverse == astrology 2?
    This is of course a math forum debating some deep physics questions, and one could be forgiven for thinking that the math guys are just sour because they haven’t been made an offer by the physics funding machine.

  39. Joel Rice says:

    The trouble with the LHC is that it has not put a nice juicy Discrepancy on the table, like a Lamb Shift to cast doubt on Dirac, so there would be a real problem to work on. It is curious that they want to speculate about multiverses rather than why muons exist.

  40. why muons exist says:

    Joel Rice – Thanksgiving is over, but at Christmas dinner I suggest you engage the family in a discussion “why are there multiple families of leptons?” Don’t blame anyone but yourself if you are dunked in a pot of boiling oil.

    Trevor Turton – “… one could be forgiven for thinking that the math guys are just sour because they haven’t been made an offer by the physics funding machine.” The vaunted “physics funding machine” is regularly starving for money, so if the math guys are sour, I can only imagine they receive negative funding.

  41. Puzzled says:

    Just a quick comment… afaik “epicycle” models of planetary orbits were never proven “wrong”, per se. In fact, it’s a small exercise in Fourier analysis to develop a “sum of complex exponentials” (e.g. circular orbits) that would approximate any ellipse to any degree of accuracy you want. That ellipses are simpler solutions to a differential equation formulated according the invers-square gravitation than sums of complex exponentials is nice for planetary orbit calculations.

    But one could also use the Fourier decomposition as a more general way to solve a much larger class of theories about gravitation (including some problems in GR). So maybe there are two “aha” ideas here: Fourier analysis, which is a truly great idea (and more or less the same as epicycles) and Kepler’s Laws, which is a truly great idea about observed physical reality. But one could keep epicycles and still have Newton’s Law… and you still need a version of “epicycles” calledFourier analysis to do good solutions to large classes of differential equations.

    Which is the “truth”? There is no “law of the excluded middle” here… both are simultaneously likely to be true. I’d suggest forgetting about truth, and focus on what a theory gives us as ways of knowing. There multiverses and string theory both are pretty barren deserts.
    Falsifiability is not enough, nor is

  42. Coin says:

    Bernhard: “the only scalar existing at the weak scale is the Higgs”

    It would be awfully interesting to compile a list of anthropic-reasoning arguments whose conclusions are, or sometime after being made turn out to be, in conflict with experiment. It seems like you should be able to find plenty of anthropic arguments which are structurally as sound as the ones multiverse advocates commonly cite, but produce factually incorrect results…

    TAM: “‘This is not like the beginning of the last century when there were a lot of experimental hints pointing in promising directions.’ They key is *experimental hints*. That is the really lacking ingredient in these modern times.”

    You know, this is an oft-repeated thing, and I understand what you and Peter mean by it, but I don’t really feel like it’s true and it seems to get less and less true all the time. It seems like we keep stumbling over all kinds of fascinating experimental hints all over the place, but it’s not convenient or doesn’t come in the form physicists know how to easily consume it (ie a scattering diagram) so we scratch our heads and go “huh, that’s funny, well let’s see what the LHC finds”. Dark energy is the biggest, most burningly difficult to ignore example here. Colliders might not have found any new particles in decades, but astronomy has (my understanding is that the bullet cluster observation can only be explained by the existence of a WIMP-like particle). Every time we poke at neutrinos we find more strange things about them– the OPERA result is probably BS, but “how fast do neutrinos move and what is their rest mass?” seems like an incredibly tantalizing question which no one seemed very interested in until the OPERA BS result threatened Einstein. And in areas I don’t understand so well we seem to be learning more about inflation all the time, UHECRs are a thing, quantum computers are coming online…

    And a lot of these “hinty” areas of physics, it seems to me we could be pushing a LOT harder than we are, there are whole experimental avenues that could be full of even stranger things but which we’re just not really exploring. In particular look at all the astrophysics probes that have been cancelled since 2006 (Google “beyond Einstein program”, it’s sad) climaxing with LISA finally biting the bullet just a few months ago– astronomy has been one of the most productive sources of new experimental physics data in the last ten, fifteen years but there seems to be very little interest in or pressure toward funding astrophysics.

    I’m not sure I’m qualified to make a statement like thus, but– I really feel like it’s possible someone a hundred years from now could look at this period and see not a period devoid of experimental hints, but a period when we were awash in hints we just didn’t understand what to do with and leads it didn’t occur to us to explore.

  43. Peter Woit says:

    All,

    A reminder: this isn’t a general physics discussion forum, there are good reasons why I refuse to moderate such a thing. The topic might be kind of dumb and tedious, but if what you want to write about is something else, please restrain yourself…

  44. archytas says:

    Peter,

    I read Deutsch’s “Fabric of Reality” (not to be confused with “Fabric of the Cosmos”). As I recall, one of his main arguments for the many worlds interpretation of qm had to do with a photo’s behavior in a Mach–Zehnder interferometer. He argued that the photon was interfering with itself in another universe. I am probably not doing it justice without an exact quote. I only mention this, because I know there was more to his argument than just the computational power of a quantum computer.

    It was an interesting read, but one cannot help but be bothered by the ontological cost the MWI, which is infinite by my estimate.

  45. Bernhard says:

    Coin,

    The problem with these kind of arguments is that they are never unique and cannot be made to disprove the theory. You can, as you said, come up with hypothesis with verifiable consequences and claim they each one of them is anthropic inspired. But what’s the point? What is happening is clearly that only one part of the argument is really being tested. If a multiverse could be tested by simply saying “if anthropic reasoning is right than there must be a single Higgs scalar and the consequences are A, B and C. If not, the multiverse idea must be abandoned”, than I’m all for it. But that is clearly not what’s happening. If this supposed anthropic argument fails, you just come up with another one, if fails, with another one and so for. Eventually I can see someone making the correct assumption but I doubt there is any reason to believe it would be correct because of anthropic reasoning, even if one can trivially find a connection with it.

  46. You may like to consider that many worlds and multiverses are much much older than those guys you apparently do not like.
    More hype for the multiverse “fary tale” right here:
    http://www.science20.com/alpha_meme/modest_agnostics_expect_multiverse_and_hold_many_worlds_true-85038

  47. Joel Rice says:

    What bothers me about the sorts of things Brian Greene says is the implication that there is no particular necessity that the universe we observe be this way, other than being in a Bang where the fine tuning goes our way – as if that is the only reasonable way to look at fine tuning. Where is the necessity of having a particular kind of collection of particles? If that structure of matter is determined by some algebra then all universes ought to be equivalent – the necessity of this universe having electrons is the same necessity in any universe. It is a structural thing rather than a matter of coupling constants. Of course, if particles are stringy then one has a lot more flexibility – the question is whether there is too much flexibility. I always wonder if we are not skipping over algebraically elementary stuff when we are trying to explain physically elementary stuff. Things might be fine tuned for reasons that have nothing to do with coupling constants – if algebra determines what associates with what, and coupling is just a phenomenological device for description. The Multiverse says you do not get the big picture from looking at this universe. Is that an algebraically reasonable thing to assert ? It seems to follow from their assumptions. One might say we don’t see supersymmetry because of the multiverse, but I am more comfortable saying we don’t see it because it isn’t there.

  48. Pingback: Uncommon Descent | “Zero skepticism” and “outrageous hype,” not evidence, mark recent campaign to make multiverse respectable – mathematician

  49. dane says:

    thanks for sharing this! im gonna bookmark your site!!

  50. lun says:

    One of the “usual suspects” is currently giving a talk in Columbia,essentially about this paper
    While being skeptic,I have to admit this IS kind of thought-provoking, and he does have a kind of a non-trivial post-diction (he calls it a prediction). If it was really true that one can relate the cosmological constant “coincidence” to the (in principle calculable) number of states in the landscape,it would be something approaching a phenomenology.

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