Brian Greene’s The Elegant Universe is being reissued today, in a 25th anniversary edition. It’s the same text as the original, with the addition of a 5 page preface and a 36 page epilogue.
The initial excitement among some theorists in late 1984 and 1985 that string theory would provide a successful unified theory had died down by the early 1990s, as it had become clear that this was not working out. This didn’t stop the theory from continuing to be sold to the public in hype-heavy books such as Michio Kaku’s 1995 Hyperspace. Interest in string theory among theorists was revived in the mid-nineties by the advent of branes/dualities/M-theory. The publication of the The Elegant Universe in 1999 brought to the public the same hyped story about unification, together with the news of the new “M-theory”. The book was wildly successful, selling something like 2 million copies worldwide. A 3-hour PBS special based on the book reached an even larger audience.
From the beginning in 1984 I was dubious about string theory unification, and by the late 1990s could not understand why this was dominating physics departments and popular science outlets, with no acknowledgement of the serious problems and failures of the theory. From talking privately to physicists, it became clear that the field of particle theory had for quite a while become disturbingly tribal. There was a string theory tribe, seeing itself as embattled and fighting less intelligent other tribes for scarce resources. Those within the tribe wouldn’t say anything publicly critical of the theory, since that would not only hurt their own interests, but possibly get them kicked out of the tribe. Those outside the tribe also were very leery of saying anything, partly because they felt they lacked the expertise to do so, partly because they feared retribution from powerful figures in the string theory tribe.
At some point I decided that someone should do something about this, and if no one else was going to say anything, maybe I needed to be the one to do so. My unusual position in a math department pretty well insulated me from the pressures that kept others quiet. I’ve told the story of the article I wrote starting at the end of 2000 here. It was put on the arXiv in early 2001 and ultimately published in American Scientist. Looking at it again after all these years, I think the argument made there stands up extremely well. While there was no direct reference to the Greene and Kaku books, there was:
String theorists often attempt to make an aesthetic argument, a claim that the theory is strikingly “elegant” or “beautiful”. Since there is no well-defined theory, it’s hard to know what to make of these claims, and one is reminded of another quote from Pauli. Annoyed by Heisenberg’s claims that modulo some details he had a wonderful unified theory (he didn’t), Pauli sent his friends a postcard containing a blank rectangle and the text “This is to show the world I can paint like Titian. Only technical details are missing.” Since no one knows what “M-theory” is, its beauty is that of Pauli’s painting. Even if a consistent M-theory can be found, it may very well be a theory of great complexity and ugliness.
The subject of string theory and the state of fundamental physics was complicated and interesting enough that I thought it deserved a book length treatment, which I started writing in 2002 (the story of that is here). The book I wrote was not a direct response to The Elegant Universe, but was an alternative take on the history and current state of the subject, trying to provide a different and more fact-based point of view.
During this time, Kaku came out with his own M-theory book, Parallel Worlds, published in 2004. Also in 2004, Greene published a follow-up to The Elegant Universe, entitled The Fabric of the Cosmos, which was the basis several years later of a four-hour Nova special.
Over the last twenty-years there’s been no let up, with Kaku’s latest The God Equation, yet another hype-filled rehash of the usual string theory material. Greene regularly uses his World Science Foundation to do more string theory promotion, most recently putting out “The State of String Theory”, where we learn the subject deserves an A+++.
In recent years I’ve often heard from string theorists who feel that their research is getting a bad name because of the nature of the Greene/Kaku material. They see this hype as something that happened long ago, back before they got into the subject, so ask why they should be held accountable for it. When asked why they won’t do anything about the ongoing hype problem, it becomes clear that string theory tribalism is still a potent force.
Turning to the new material in this new edition of the book, much of it is the usual over-the-top hype, although often in a rather defensive mode:
the past twenty-five years have been such an astonishingly productive period that exploring progress fully could easily fill an entire book on its own… The fact is, the past twenty-five years have been jam-packed with discoveries in which string theorists have scaled towering problems and dug deeply into long-standing mysteries… the decades of rich development in string theory carried out by some of the most creative, skeptical and discerning minds on the planet is the most readily apparent measure of the field’s vitality. Scientists vote with their most precious commodity — their time. By that measure, and correspondingly, the measure of vibrant new ideas that have opened stunning vistas of discovery, string theory continues to be a source of inspiration, insight, and rapid progress.
While some scientists have left the field
others, indeed so many others that string theory has been berated by for attracting too many of the highest-caliber scientists, have found that the pace of new theoretical discoveries and novel physical insights is so rapid and thrilling that they are propelled onward with vigor and excitement.
The epilogue mostly deals with three topics. The first is the failure to find SUSY at the LHC, which Greene explains is perfectly compatible with string theory, and that, even before the LHC turned on:
there were theorists at that time who emphasized that string theory seems to favor superheavy superpartners, far too massive for the Large Hadron Collider or even any remotely realistic next-generations colliders to produce.
He acknowledges that at the present time string theory predicts nothing at all about anything, that even if we had a Planck scale collider:
We would still need to understand the theory with greater depth to make detailed comparisons between calculations and data, but in that imagined setting experiment would guide theorizing much as it has across a significant stretch of the history of physics.
The second topic is the string theory landscape and the anthropic multiverse “prediction” of the CC, with about ten pages devoted to explaining that
the dark energy has its measured value because if its value had been significantly different, we would not be here to measure it.
The final topic, taking up twelve pages, is AdS/CFT. The conclusion is that:
We now have powerful evidence that — shockingly — string theory and quantum field theory are actually different languages for expressing one and the same physics. In consequence, the experimental luster of quantum field theory casts a newfound experimental glow on string theory.
No more “what is M-theory?”, instead we’re told that the question “What is the fundamental principle underlying string theory?” gets answered by:
the new lesson seems to be that quantum mechanics already has gravity imprinted into its deep structure. The power of string theory is that its vibrating filiaments allows us to more easily see this connection.
The last section is “A Final Assessment.” No A+++, but:
In the arena of unification, both in terms of showing that gravity and quantum mechanics can be united as well as demonstrating that such a union can embrace non-gravitational forces and matter particles too, I give string theory an A. String theory surmounts the difficult mathematical hurdles that afflicted earlier work on unification and so, at least on paper, establishes that we have a framework in which the dream of unification can be realized.
In the arena of experimental or observational confirmation, I give string theory an incomplete.
One thing I was looking for in the new material was Greene’s response to the detailed criticisms of string theory that have been made by me and others such as Lee Smolin and Sabine Hossenfelder over the last 25 years. It’s there, and here it is, in full:
There is a small but vocal group of string theory detractors who, with a straight face, say things like “A long time ago you string theorists promised to have the fundamental laws of quantum gravity all wrapped up, so why aren’t you done?” or “You string theorists are now going in directions you never expected,” to which I respond, in reverse order “Well, yes, the excitement of searching into the unknown is to discover new directions” and “You must be kidding.”
As one of the “small but vocal group” I’ll just point out that this is an absurd and highly offensive straw-man argument. The arguments in quotation marks are not ones being made by string theory detractors, and the fact that he makes up this nonsense and refuses to engage with the real arguments speaks volumes.
Note: after tomorrow I’ll be on a short vacation for a while in San Francisco and dealing with blog comments might take longer than usual.
You said Green’s sold two millions. Just to have an idea of the impact of the critics versus hype, how much did you sell with your book ?
martibal,
I didn’t pay much attention to that number, and almost all the sales were long ago (the book now sells only a small number of copies/year). I think the right order of magnitude was significantly more than 10,000, significantly less than 100,000.
I was one in a generation of physicists motivated to study string theory in graduate school in large part due to The Elegant Universe (I was in high school when it was first published). My entering graduate class at Stanford almost 20 years ago started with about a dozen students who initially wanted to study string theory, but nearly all moved on to other realms of theoretical physics after taking a course or two on string theory as first years. I think among many students then it became very obvious very quickly that the purported beauty of string theory was at most skin deep.
It’s a rather disappointing irony that with this re-release of The Elegant Universe, Greene seems to have leaned in to the content of the second half of the book, which was by far weaker than the first half (even with no skin in the string theory game). At the time anyway, from my naive student perspective, there were very few titles on the market that made the oddities and confusions of quantum mechanics and relativity so accessible and engaging as the first half of The Elegant Universe. With major results and Nobel prizes in both of these fields since its initial publication, it seems rather a shame that he has just doubled down on string theory. Though I guess that is at least consistent with the World String Festival that he hosts.
I read The Elegant Universe just before starting my undergraduate degree and was totally convinced by it that string theory was going to solve all of physics. It took a few months of studying in a physics department full of actual particle physicists to realise none of them took it seriously, and most of them thought it was embarrassing. I tried to watch the ‘The State of String Theory’ panel discussion but gave up very quickly once it turned into an uncritical string theory love-in. Michio Kaku has a lot to answer for, but I think Brian Greene is up there for guilt in terms of misinformation.
I did an undergraduate degree in theoretical physics thanks to books by Kaku and Greene. Thankfully an experimental particle physicist convinced me I would be better off switching to experimental work for my PhD.
It’s interesting to see that the comments back up an argument I’ve often heard from physicists when I criticize books like this. They tell me “sure, the material in that book about string theory is nonsense and misleading the public, but it’s getting young people excited about physics and interested in becoming physicists. Once they do become physicists they’ll realize this is nonsense and go on to do some real physics.”
I believe that, in that book, Greene told the story of my once PhD advisor, the late Stein Arild Strømme and Geir Ellingsrud finding the wrong number of twisted cubics on the general quintic threefold, only to be corrected by a new string theory way of coming up not only with the corrected number but a recursive formula for degree d rational curves on there. Stein Arild quickly found the coding error and gave string theorists a win. That complex quintic threefolds are real six dimensional spaces with flat metric that could curl up in every space time point making ten dimensions and rational curves being important in that theory and giving candidates for a model of our world suddenly was all the rage. If I recall correctly there were too many candidates. However the count of 317206375 still stands. Not even wrong, being a fitting phrase for it.
thphys, that sounds like the incoming class of 2007. I was there and can confirm. I remember during graduate school orientation when a string theorist told the incoming particle theorists, “We don’t have room for all of you, so you’ll have to switch to something else.” That’s right after they admitted us knowing our intentions, and we accepted.
It’s an interesting phenomenon of unintentional bait and switch. Physics departments love the extra attention, publicity, and enrollment figures, but not everyone likes the field that is doing the recruitment.
In 1967 I was a Chemistry grad student (doing scattering experiments and their theory) and took an advanced QM course in Chemistry and sat in on Glashow’s second-level physics course. One big thing at the time was (the tail end of) S-matrix theory and Regge Trajectories.
Today I was looking in Wikipedia and found, in an article on Quantum Chromodynamics the following:
“The relation between the short-distance particle limit and the confining long-distance limit is one of the topics recently explored using string theory, the modern form of S-matrix theory.”
To me that seems to be very damning.
Doug McDonald,
It’s more the amplitudes program that is the modern form of S-matrix theory. String theory is something much worse….
That sentence is complete nonsense, and the quoted papers don’t correspond to the claim. The idea that QCD in some other variables is some sort of string theory has been around for a very long time, I spent a lot of time thinking about that in grad school. The problem is exactly the opposite of what the sentence says: no one has any idea how to get the asymptotic freedom of QCD out of string theory.
To help Wikipedia out I deleted that sentence.
Thanks for correcting Wikipedia.
I am not aware of anyone holding so much as a single multi-day conference on physics forcing a re-examination of whether this is “Academic Capture” by string theorists where the leaders of the failed string generation were forced into head to head contact with String Theory’s critics.
By my estimation, it would cost the same ammount in 2024 dollars for a string of 3 conferences like Shelter Island, Oldstone and Poccono cost in the 1940 when Fundamental Physics ended its 19 year stagnation. Surely I am not the only one to have noticed this. Yet everyone treats this as if it were madness. Odd no?
Is there ever a point when this is too long, failed and insane to be a mistake, fad or accident? Would that be 50 years? 100 years? 200 years?
I don’t think in 2024, this is gauranteed to be a bug. I think it must be considered at this point that we may be looking at a feature. String theory, unlike real physics, is safe and has that as an actual major advantage over say the Spinorial/Twistor approaches. Further it only acknowledges one rival that it has chosen itself (LQG) and only aggrees to contests it, itself judges by String standards.
Real physics remains the most dangerous subject known to man, as we know from WWII, Castle Bravo and the Atomic Energy Acts of 1946 and 1954. Imagine what the next theory might bring. It could be arbitrarily powerful and much easier to deploy.
String theory doesn’t confer military advantage. It’s harmless. You can do it with your friends. You can do it with your rivals. It’s totally harmless and safe. What it does is simple to state: it kills funding, interest, morale and opportunity in vital rival theories of physics while stagnating the field, far better than any known alternative. It’s a near perfect sterility program.
But, of course, that is madness to suggest that $500,000 dollars (or less!) could be used to figure out whether this is the only game in town as claimed by people who refuse to constructively and collegially engage their colleagues. After all, our String Theorists are far too busy succeeding and winning to consider wasting their precious time on alternatives…IYKYK. 😉
I attended the “State of String Theory”. Although Andy Strominger gave it an A+ (as opposed to an A+++, David Gross gave it a B+ and Ed Witten declined to give it a letter grade. Cumrun Vafa was a no show on the panel due to Covid.
Those of us who know, know. But if you were at Harvard in 1985 you know very smart people were pretty dubious about string theory but said “Hey let Ed go with it, he’s unbelievably smart.” I was there when Schwartz came to Jefferson Hall and spoke about the cancellations. It was interesting. There was still a lot of scepticism even then. It is sad to see what has become of Brian Greene. Not much else has worked out either.
The only string theorist I can recall who actually engaged in responding at least a few of the arguments made by you and Smolin was the late Polshinski, at least in the beginning. Since then, it has always been straw-man attacks.
@Carl Feinberg. Strominger gives an A++ earlier in the discussion (at 43:00). Without any irony, he adds that otherwise he wouldn’t be working in it.
This book is notorious for being solely responsible in making a bunch of millennial string theorists who now have no choice but to do string theory if they want an academic job.