David Gross has in the past invoked the phrase “never, never, never give up”, attributed to Churchill, to describe his view about claims that one should give up on the traditional goals of fundamental physics in favor of anthropic arguments invoking a multiverse. Steven Hawking has a new book out this week, called The Grand Design and written with Leonard Mlodinow, in which he effectively announces that he has given up:
We seem to be at a critical point in the history of science, in which we must alter our conception of goals and of what makes a physical theory acceptable. It appears that the fundamental numbers, and even the form, of the apparent laws of nature are not demanded by logic or physical principle. The parameters are free to take on many values and the laws to take on any form that leads to a self-consistent mathematical theory, and they do take on different values and different forms in different universes.
Thirty years ago, in his inaugural lecture as Lucasian professor, Hawking took a very different point of view. He argued that we were quite close to a final unified theory, based on N=8 supergravity, with a 50% chance of complete success by the year 2000. A few years after this, N=8 supergravity fell into disfavor when it was shown that supersymmetry was not enough to cancel possible ultraviolet divergences in the theory. There has been a recent revival of interest as new calculational methods show unexpected and still not completely understood additional cancellations that may fully eliminate ultraviolet divergences. Hawking shows no interest in this, instead signing on to the notion that “M-theory” is the theory of everything. The book doesn’t even really try to explain what “M-theory” is, we’re just told that:
People are still trying to decipher the nature of M-theory, but that may not be possible. It could be that the physicist’s traditional expectation of a single theory of nature is untenable, and there exists no single formulation. It might be that to describe the universe, we have to employ different theories in different situations
The book ends with the argument that
ergo
M-theory is the unified theory Einstein was hoping to find. The fact that we human beings – who are ourselves mere collections of fundamental particles of nature – have been able to come this close to an understanding of the laws governing us and our universe is a great triumph.
This isn’t exactly an air-tight argument…
The book begins in a more promising manner, with a general philosophical and historical discussion of fundamental physical theory. There’s this explanation of what makes a good physical model:
A model is a good model if it:
1. Is elegant
2. Contains few arbitrary or adjustable elements
3. Agrees with and explains all existing observations
4. Makes detailed predictions about future observations that can disprove or falsify the model if they are not borne out.
The fact that “M-theory” satisfies none of these criteria is not remarked upon.
The book is short (about 100 pages of actual text, interspersed with lots of color graphics and cartoons), and contains rather little substantive science. There are no references of any kind to any other sources. The discussion of supersymmetry and M-theory is often highly misleading. For example, we are assured that
various calculations that physicists have performed indicate that the [super]partner particles corresponding to the particles we observe ought to be a thousand times as massive as a proton, if not even heavier. That is too heavy for such particles to have been seen in any experiments to date…
With no references, one has no idea what these “various calculations” might be. If they are calculations of masses based on the assumption that the supersymmetry and electroweak-symmetry breaking scales are similar, they typically predict masses visible at the Tevatron or LEP. I suspect that the logic is completely backwards here: what is being referred to are calculations based on the Tevatron and LEP limits that require masses in the TeV range.
As for the fundamental problem of testability of M-theory, here’s the only thing we get:
The theory we describe in this chapter is testable…. The amplitude is reduced for universes that are more irregular. This means that the early universe would have been almost smooth, but with small irregularities. As we’ve noted, we can observe these irregularities as small variations in the microwaves coming from different directions in the sky. They have been found to agree exactly with the general demands of inflation theory; however, more precise measurements are needed to fully differentiate the top-down theory from others, and to either support or refute it. These may well be carried out by satellites in the future.
This looks like one of many dubious claims of “testability” of multiverse theories, which tend to founder on the measure problem and the fact that one has no idea what the underlying theory actually is. Without any details or references though, it’s hard to even know exactly what the claim is here.
One thing that is sure to generate sales for a book of this kind is to somehow drag in religion. The book’s rather conventional claim that “God is unnecessary” for explaining physics and early universe cosmology has provided a lot of publicity for the book. I’m in favor of naturalism and leaving God out of physics as much as the next person, but if you’re the sort who wants to go to battle in the science/religion wars, why you would choose to take up such a dubious weapon as M-theory mystifies me. A British journalist contacted me about this recently and we talked about M-theory and its problems. She wanted me to comment on whether physicists doing this sort of thing are relying upon “faith” in much the same way as religious believers. I stuck to my standard refusal to get into such discussions, but, thinking about it, have to admit that the kind of pseudo-science going on here and being promoted in this book isn’t obviously any better than the faith-based explanations of how the world works favored by conventional religions.
For some reviews of the book showing a bit of skepticism, see ones by Craig Callender, Fred Bortz, and Roger Penrose. For much more credulous reviews, see for example James Trefil (who evidently has his own multiverse book coming out). The Economist has a news story about this, which assures us that Hawking is
a likely future recipient of the Nobel prize in physics (if, as expected, his 1974 theory that black holes emit radiation despite their notorious all-engulfing gravitational pull is confirmed by experiments at the Large Hadron Collider in CERN).
Update: There’s a new posting at physicsworld.com by Hamish Johnston that brings up the issue of the potential damage caused by this to the cause of science funding in Britain:
This morning there was lots of talk about science on BBC Radio 4’s Today Programme — but I think it left many British scientists cringing under their duvets.
Hawking explained that M-theory allows the existence of a “multiverse” of different universes, each with different values of the physical constants. We exist in our universe not by the grace of God, according to Hawking, but simply because the physics in this particular universe is just right for stars, planets and humans to form.
There is just one tiny problem with all this — there is currently little experimental evidence to back up M-theory. In other words, a leading scientist is making a sweeping public statement on the existence of God based on his faith in an unsubstantiated theory…
Physicists need the backing of the British public to ensure that the funding cuts don’t hit them disproportionately. This could be very difficult if the public think that most physicists spend their time arguing about what unproven theories say about the existence of God.
Update: Today’s Wall Street Journal has a quite positive review of the book by Sean Carroll.
Update: See here for John Horgan’s take on the Hawking book:
I’ve always thought of Stephen Hawking—whose new book The Grand Design (Bantam 2010), co-written with Leonard Mlodinow, has become an instant bestseller—less as a scientist than as a cosmic, comic performance artist, who loves goofing on his fellow physicists and the rest of us…
Toward the end of the meeting [in Sweden, 1990], everyone piled into a bus and drove to a nearby village to hear a concert in a Lutheran church. When the scientists entered the church, it was already packed. The orchestra, a motley assortment of blond-haired youths and wizened, bald elders clutching violins, clarinets and other instruments, was seated at the front of the church. Their neighbors jammed the balconies and seats at the rear of the building.
The scientists filed down the center aisle to pews reserved for them at the front of the church. Hawking, grinning ear to ear, led the way in his motorized wheelchair. The townspeople started to clap, tentatively at first, then passionately. These religious folk seemed to be encouraging the scientists, and especially Hawking, in their quest to solve the riddle of existence.
Now, Hawking is telling us that unconfirmable M-theory plus the anthropic tautology represents the end of that quest. If we believe him, the joke’s on us.
Hawking love-story with the media and the masses intimidates many shy-away-from-the-media scientists, mainly by pushing the image of science far into mysticism and a misleading populism, which bluntly exploits the layperson ignorance of what is verifiable science. But the root problem is not Hawking but the many opportunistic scientists that support and even exploit such an approach to the fundamental pillars of verifiable science. Without their support the media would have failed to make an icon out of this false prophet; would at least resort to the audacity of truth: The entire Hawking festival does not even rise to the level of being wrong in the domain of verifiable science.
An unknown personal fact is added next:
Nature was among the first to publish a review on my “Cosmology, Physics and Philosophy” [1981, 1983, 1987, Springer Verlag], which, inter alia, contained criticism of Stephen Hawking’s theories as lacking any possible future verification and some are not his but of J. D. Beckenstein.
The review was written by Hawking, who hinted there that instead of my not-easy-to-understand book he would write one for the masses , which he did in 1988 by omitting all mathematical equations and adding mysticism. [BTW: As far as I know some key Hawking’s claims in science were first ridiculed by professor Yuval Neeman.]
[“People University Online”, Cf. my Facebook].
i wonder if hawking ever read feynman’s cargo cult science speech?
“The first principle is that you must not fool yourself–and you are
the easiest person to fool. So you have to be very careful about
that. After you’ve not fooled yourself, it’s easy not to fool other
scientists. You just have to be honest in a conventional way after
that.
I would like to add something that’s not essential to the science,
but something I kind of believe, which is that you should not fool
the layman when you’re talking as a scientist. I am not trying to
tell you what to do about cheating on your wife, or fooling your
girlfriend, or something like that, when you’re not trying to be
a scientist, but just trying to be an ordinary human being. We’ll
leave those problems up to you and your rabbi. I’m talking about
a specific, extra type of integrity that is not lying, but bending
over backwards to show how you are maybe wrong, that you ought to
have when acting as a scientist. And this is our responsibility as
scientists, certainly to other scientists, and I think to laymen.
So I have just one wish for you–the good luck to be somewhere
where you are free to maintain the kind of integrity I have
described, and where you do not feel forced by a need to maintain
your position in the organization, or financial support, or so on,
to lose your integrity. May you have that freedom.”
http://www.lhup.edu/~DSIMANEK/cargocul.htm
These are the problems with Mlodinow’s other books.
How much of this did he write?
neo,
“Stephen’s (not Steven’s!) accomplishments speak for themselves. Why he has embarked on this exploitation tangent is beyond me.”
i bet it’s for the money. what else could it be?
“Stephen’s (not Steven’s!) accomplishments speak for themselves.”
What experimentally verified accomplishments were those?
Question from a non-physicist:
First of all, in the Feynman path integral theory, how in the world do you make sense mathematically of the constant branching of possibilities in all places and at all moments? (Since apparently quantum mechanics is not simply a diffusion process). Maybe the answer is that measurements take place only at discrete places and times. But then same question re the many-worlds theory (since then presumably this splitting takes place everytime and place). I mean is there a mathematical way of formulating this at all, even approximately? I am thinking that the number of possible worlds should
certainly not exceed the continuum in cardinality (!) and should in fact lead to a measure space. Now naively the problem seems to be magnified enormously with the landscape idea… especially if it’s infinity and not just 10^500. (???) Enlighten a bit please!
My impression is things are way too speculative for Hawking to put his considerable scientific and public weight on one side of the scale…unless of course he REALLY believes what he is saying.
Bugsy,
You are conflating things that have very little to do with each other.
1. The Feynman path integral. This is the notion that a system takes all possible paths from a state at an earlier time to a later time, but only the ones which follow the “correct” equations of motion are actually seen because of phase cancellations. It may or may not be rigorous, depending who you talk to. Either way, though, I personally have never understood (or seen the point of) it.
2. The measurement problem in quantum mechanics. Physical observables are only ever eigenvalues of some quantum operator. This does not require and has nothing to do with path integrals, or String Theory.
3. The Landscape in String Theory. The world is, as far as we know, 3+1 dimensional. String Theory is typically 10+1 dimensional. The process of losing dimensions is called compactification and current understanding is that the process can be done in about 10^500 different ways. The options are thus either (i) to give up or (ii) to say that because string must be right physics can therefore be reduced to choosing the right one of these compactifications.
Whether Hawking believes in (ii) or not is not so much the issue as whether anyone should care if he does. However I have noted generally a tendency for the elder statesman of the physics community (with the possible exception of Veltman) to support the status quo, whatever that may happen to be.
After reading here and other places, I went to my sister-in-law the aquatic biologist, with the happy news that now that physics has been freed from the requirement of actually being tied to physical evidence that she didn’t have to go out this winter to do her sampling anymore. She wasn’t as happy about it as I thought she would be, though she did take the opportunity to vent about theoretical physicists and cosmologists, their politics, their dirty politics and their hogging of funding. I think she might have felt better after that.
Being a complete outsider I have to say that the idea of an entirely artificial physics generating an entirely artificial mathematics to service it gave me a lot of entertainment while I was doing my chores this weekend. It came to me that the results might be a science that has has more in common with fan fiction than it does the natural universe. But that’s only a musician’s view of it.
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True story, I was at a math conference maybe 15 years ago, at a talk on something to do with Riemann surfaces, and the number 26 (or maybe 24) kept coming up. Someone asked “is that the 26 dimensions from string theory?” (back then, if I remember correctly, string theory somehow involved 24 maybe + 2 dimensions?). At least now they’ve got it down to 10 + 1. I’ve been told by several very good mathematicians who are much more involved than I am that there is very interesting math involved in string theory, then again, sometimes I get the impression that it’s actually inconsistent, and you can prove anything you want to…
I’m just a layman, but do have an interest in what makes our world tick, and I tend to buy most of the popular physics books to try to understand current thinking.
I was very disappointed in Hawking’s book. My full review of it is here.
But, in short, he makes no attempt to summarize the various ideas regarding the origin of our universe and to say why M-theory is a better candidate … he basically just says it is, like we are supposed to believe him. The problem is, many will just believe him, and will never know that there are competing theories. And to treat cosmic inflation and supersymmetry as fact is just downright deceitful, given that many of his readers will never know that there are many reputable physicists who dispute both. (For all I know, both theories are true, but they are certainly not established fact.)
Jeff,
Actually there is some quite good mathematics related to string theory, problem is that it tends to be orthogonal to those parts of string theory that are supposed to give unification.
The number 26 of dimensions for the critical bosonic string does have a nice relation to the moduli space of Riemann surfaces. The 10 for superstring theory less so. This is kind of typical: as you focus on those aspects of string theory that might give unification, things become more and more complicated, less and less mathematical elegance is to be found.
Peter,
It was a moduli space thing where the 26 came up, back then I had very little to do with that sort of thing, now I’m big into Teichmuller theory, go figure. I do know there is quite interesting math lurking around, interesting what you say about the loss of elegance. Maybe that’s why I ended up in math, much easier not to end up jamming a square peg into a round hole.
Chris (Oakley),
Thanks for your patient response.
I guess I was conflating “many paths”, “many worlds”, and “many universes”! And wondering if anyone thinks all three belong in the same “model”, and further wondering if any of that can be formulated mathematically in any sense at all. Is there an actual topological space,
or measure space, which should be phase space, acted on by the dynamics of time evolution?
To try your patience one more time:
from what you say it seems the number 10^500 is really meant to be finite, as it comes from topological or algebraic considerations, and is not a continuum. Does that mean the possible values for each of the various physical constants are also of that number? (Is there a map from the compactification space to a vector space of possible constants?)Thanks….!
Cosmic Clowning: Stephen Hawking’s “new” theory of everything is the same old CRAP
Hat tip: Lubos
However a church in Sweden does not mean the people in it are religious… might have clapped just because of his fame…
On these blogs and elsewhere i often read word to the effect that
‘ string theory might not cut it as a physical theory, but it has led to very interesting mathematics”.
Just what is this ‘interesting math’ ??
Can anyone refer me to a book or article for non-specialists that communicate this?
(I am mathematically and scientifically literate (phd theoretical physics, Columbia U 1966), so it needn’t be a words-only book for a popular audience. ) I follow current physics developments as an
interested outsider, and i’m genuinely interested in knowing about the interesting mathematics that is coming from superstring research.
Steve,
My book “Not Even Wrong” has a bit about this. There’s a new book by Yau and Nadis that just came out (The Shape of Inner Space) which has a lot more.
Bugsy,
I would rather not go there – it is too depressing. If it was me I would have thrown out the theory as soon as I discovered that it did not work in 3+1 dimensions. But yes, each string vacuum (=compactification) has its own mass spectrum and coupling constants. The only things that are common are c (the speed of light), h (Planck’s constant) and G (the gravitational constant).
Chris,
The gravitational constant is not common in all compactifications. It depends on the volume of the extra dimensions.
Bugsy writes:
Yes, it’s supposed to be finite – but as far as I can tell, it’s just a wild guess, or maybe a lower bound. It’s gone up a lot during my lifetime. 🙂
However, I believe that beyond this large finite number of choices, there are also theories that involve choices that come in continuous families. The buzzword is “moduli space”.
There are lots of theories with different numbers of particles, different kinds of particles, etc. Then you get to choose certain numbers governing the behavior of these particles.
Hello Professor Baez!
Where do Hawking & Sean Carroll rank on your crackpot index?
“The main reason I wrote about the Bogdanov story, (besides for its entertainment value), is that I think it shows conclusively that in quantum gravity in general, many people have lost the ability or willingness to recognize non-sense for what it is.”
Could this quote from you, Peta, also describe Hawking’s purpose for writing the book? If so, it reminds me of Picasso’s descriptions of the kind of stuff that art galleries promote. I seem to recall an interview with the painter on “60 Minutes” where he confessed to trying to find how far the art world would follow him.
Glenn,
The Bogdanov story was pretty different. They were producing sophisticated sounding gibberish, which required some expertise to recognize as such. The multiverse stuff being promoted by Susskind, Hawking and many others uses no sophisticated math, and is easy to understand. It’s quite easy for even a non-expert to quickly realize that this is not legitimate science. Here I think the only reason that many people take it somewhat seriously is that they can’t believe that smart experts would engage in something so obviously flawed. I’m mystified by this myself…
Peter, my apologies for the last post addressing you as Peta. Although I feel that animals should be treated kindly, I have very different feelings about this handwriting recognition program on my tablet. It makes changes to previous text when I hit the submit button.
> Without any details or references though, it’s hard to even know
> exactly what the claim is here.
Something like this ?
http://arxiv.org/abs/1009.2525
tristes_tigres,
Presumably that’s it, although the book was likely written a year or so ago.
I’ll stack my guess that any such claim would have trouble with “the fact that one has no idea what the underlying theory actually is” up against the abstract’s admission that the paper’s “predictions” only apply to “a certain class of landscape models”. M-theory itself is the final theory replacing religion since it can never be falsified.
Re my request yesterday-
On these blogs and elsewhere i often read word to the effect that
‘ string theory might not cut it as a physical theory, but it has led to very interesting mathematics”.
Just what is this ‘interesting math’ ??
Can anyone refer me to a book or article for non-specialists that communicate this?
and your answer-
My book “Not Even Wrong” has a bit about this. There’s a new book by Yau and Nadis that just came out (The Shape of Inner Space) which has a lot more.
———————-
THANKS. that’s exactly what i wanted. I read your book when it first came out but i had forgotten that it covered this. I am revisiting it now with great interest and will also check out the Yau book.
I’m glad this made me look at your book again. It does a really great job of reviewing the field.
More on a rather more humorous note from Physics World’s James Dacey, excerpting this piece in the Guardian.
“Some subjects are so serious that one can only joke about them.”
— Niels Bohr (see Wikiquote)
Henrick writes:
I don’t usually go around publicly rating physicists, but I’ll do it just for you. Both these fellows have their sins, but neither are ‘crackpots’ by any stretch of the imagination. And Hawking did such incredibly profound work in his earlier years that he deserves vast amount of slack now. Don’t read his new book: read the book he wrote with Penrose, and get a beautiful description of black holes and why they radiate.
Sorry, I somehow linked to a $390 video version of the Hawking-Penrose book The Nature of Space and Time. Or something like that. I have no idea what this video is — does anyone know?
The actual book is just $14.95.
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