At Quanta magazine, IAS director and string theorist Robbert Dijkgraaf has signed up to the multiverse mania bandwagon with an article announcing There are no laws of physics. There’s only the landscape. Dijkgraaf’s version of the string landscape ideology is:
The current point of view can be seen as the polar opposite of Einstein’s dream of a unique cosmos. Modern physicists embrace the vast space of possibilities and try to understand its overarching logic and interconnectedness. From gold diggers they have turned into geographers and geologists, mapping the landscape in detail and studying the forces that have shaped it.
The game changer that led to this switch of perspective has been string theory. At this moment it is the only viable candidate for a theory of nature able to describe all particles and forces, including gravity, while obeying the strict logical rules of quantum mechanics and relativity. The good news is that string theory has no free parameters. It has no dials that can be turned. It doesn’t make sense to ask which string theory describes our universe, because there is only one. The absence of any additional features leads to a radical consequence. All numbers in nature should be determined by physics itself. They are no “constants of nature,” only variables that are fixed by equations (perhaps intractably complicated ones).
While giving the usual 1995 justification for the “M-theory” conjecture of a unique string theory, Dijkgraaf neglects to mention that, 23 years later, no one has a viable proposal for what this unique theory might be. He mentions none of the problems of moduli stabilization, or that the theorists “mapping the landscape in detail” don’t actually know what equations govern this supposed landscape and thus have hit a dead-end, unable to predict anything about anything.
The problem is that what Dijkgraaf is writing about is the situation of Theorists Without a Theory, trying to turn this failure into success by arguing that it is a radical new discovery, the discovery that “There are no laws of physics”. He ends with
A more dramatic conclusion is that all traditional descriptions of fundamental physics have to be thrown out. Particles, fields, forces, symmetries — they are all just artifacts of a simple existence at the outposts in this vast landscape of impenetrable complexity. Thinking of physics in terms of elementary building blocks appears to be wrong, or at least of limited reach. Perhaps there is a radical new framework uniting the fundamental laws of nature that disregards all the familiar concepts. The mathematical intricacies and consistencies of string theory are a strong motivation for this dramatic point of view. But we have to be honest. Very few current ideas about what replaces particles and fields are “crazy enough to be true,” to quote Niels Bohr. Like Alice and Bob, physics is ready to throw out the old recipes and embrace a modern fusion cuisine.
The argument seems to be that we need to throw out our highly successful quantum field theories, replacing them with a “radical new framework” describing “impenetrable complexity”. But what is this “radical new framework”? As best I can tell, what’s now popular at the IAS is the “it from qubit” idea that is the topic of this summer’s PITP program. It seems that Witten has taken up the study of quantum information theory, with a new expository preprint just out. I’ll look forward to seeing what the PITP lecturers present, but so far I haven’t seen the slightest indication that this “radical new framework” can get off the ground as a fundamental unified theory.
I seem to remember string theorists brushing off claims that their theory is unfalsifiable, saying something akin to ‘all you have to do to prove that String Theory is incorrect is to prove that Quantum Field Theory is incorrect.’ I guess even that is no longer the case.
It is not correct that string theory is “the only viable candidate for a theory of nature able to describe all particles and forces, including gravity, while obeying the strict logical rules of quantum mechanics and relativity.” Asymptotically Safe Gravity does this too, and if you ask me, ASG is much more viable than string theory since it doesn’t require a negative cosmological constant or extra dimensions or supersymmetry. And of course others have approaches which they claim can do it too.
I am pretty sure that Dijkgraaf knows this statement is wrong, and it’s really hard for me to read his piece as anything more than a desperate attempt at marketing.
(Since some people have recently asked me, no, I do not work on ASG.)
No guys I give up with physics if this is the mainstream idea of where our field is going. This is just babbling about something. It is like saying that the world stands on elephants on a turtle without proof. This guy has no equations, no theory, no vacuum of string theory that resembles the standard model, to coherent string theory with a positive comsmological constant, and blathers about all this. Simply incredible. Also science is entering the era of post-truth. Truth is what most of the people accepts or talk about or like, not the result of the scientific inquiry. I’m frightened that an IAS director talks like this.
Just as an historical aside, I’ll note that Dijkgraaf is incorrect in referring in his article to “the famous particle-wave duality discovered by Heisenberg.” Heisenberg didn’t “discover” wave-particle duality. Planck and Einstein (among others) had long ago supplied physical arguments that light had a particle-like nature, and de Broglie famously suggested in 1924 that electrons and other particles of matter had a dual wave-like nature. Heisenberg hadn’t burst onto the scene by that point. His big breakthrough was with matrix mechanics the following year, which was a decidedly non-wave-like approach to quantum theory.
At StringMath17 (here) I had reported on an approach to unravelling M-theory via super homotopy theory. I think it is fair to say that this looks promising, recent progress is surveyed here.
The logical flow of this article reminds me somewhat of books about the Holy Grail, Egyptian pyramids being built by aliens, etc. Possibilities are vaguely introduced, then subsequently assumed and embellished: for example para. 5 begins ‘if our world is but one among many…’ then para. 6 starts ‘the game changer that led to this switch of perspective…’ as though the new perspective was a done deal not a wild speculation.
There is also a pseudo-humility (we must accept that we cannot produce fundamental theories like the old ones) concealing an actual arrogance – i.e. there is little acknowledgment that perhaps the reason why we haven’t done it yet is because we are stuck, because it is hard, because a lot of focus is being invested in what Imre Lakotos would have called a ‘degenerating research programme’, etc. rather than because actually reality is fundamentally different to what we previously believed and we have reached the end of physics as traditionally conceived.
If this was a debate in literary theory it would be quite funny, but in physics it is sad and worrying, particularly as post-truth nonsense abounds in other areas with real and obvious real-world consequences.
I had expected better of Quanta. They’ve been reasonably good in the past at not publishing extraordinarily speculative stuff as if it’s the be-all and end-all, and they’re usually careful not to imply that high energy physics is the only branch of the discipline. Apparently not so now.
I know it probably isn’t, but I really, REALLY hope that sterile neutrino finding is valid. Because, my God, such smart people desperately need something better to be working on than this.
This isn’t so much post-truth as it is post-empiricism. And since empiricism is the sine qua non of science it is also post-science. “Impenetrable complexity” would seem the post-modern harbinger of a new dark age, one wherein the very purpose of science, to understand the nature of physical reality, is seen as a quaint anachronism.
I had the exact same impression of an earlier Dijkgraaf contribution: This is not up to Quanta standards. My suspicion at the time was maybe he was too busy to finish the article properly. Peter’s (probably more accurate) assessment was being an expert can make it very hard to write effectively for non-experts. Sometimes you need a really good science journalist to do the subject justice for lay audiences. Doubtless there’s a little of that problem involved.
But, again in agreement with you, the trouble runs much deeper. I want to know what this work tells us about OUR corner of the landscape. Because that’s the part human beings can do something remotely resembling what I like to think of as “science”, i.e. some day, some how, speculations make contact with empiracle observations. Otherwise, not only is the work perplexing, it’s profoundly BORING. I want to know what dark matter is. I want to know if there was an inflationary epoch or not. I want to know if gravity must be modified. Etc. By telling us about “everything” we are supposed to accept that it’s OK to learn precisely nothing specific about the universe we inhabit, nothing illuminating in any remotely constrained way about any of the highly observable mysteries we know exist. New experimental data can’t come fast enough.
Douglas, how can we expect better of Quanta magazine when this guy is the Director at IAS? Seriously, how can a magazine be expected to check this guy when his fellow scientists do not? This is embarrassing for the entire scientific community…
I don’t think Quanta would have published this if it were by a science journalist, it does come off as uncritical propaganda for dubious speculation. The most disturbing thing about it is that it’s not written by a lazy journalist, but by Robbert Dijkgraaf, one of the most respected and prominent figures in theoretical physics. Dijkgraaf has been one of the most influential scientists in the Netherlands and now is director of the IAS. In these roles he will have a great deal to say about the future of the field. At one point multiverse mania was concentrated on the West coast, with the IAS not following this. That seems to now have definitively changed.
Keep in mind, this isn’t the totality of physics. For perspective, high energy particle theory is only about 1% of the NSF physics budget, and only about half of that is spent on extremal ideas like this.
Unfortunately, it seems the MiniBOONE results, while congruent with LSND, are still just as confusing. Just saw a talk which explained it well. There are two elements to any neutrino oscillations–the mass difference, which gives the oscillation length, and the mixing matrix elements, which gives the oscillation amplitude. While the oscillation length from MiniBOONE/LSND suggest a 4th (sterile) neutrino, the mixing matrix elements needed are so large they should have been seen in other experiments. So it seems the simplest explanation, a 4th sterile neutrino, is still problematic. Apparently a third experiment, MicroBOONE, is in the works…
Interesting how institutions get captured by a given theory. When I was a postdoc, the Fermilab theory group was all into Technicolor. Michigan and Gordy Kane were all SUSY, all the time. And now the IAS seems to be into Landscape. I heard tales that Berkeley in the “Tao of Physics” era was the same way with whatever theory of hadrons they were peddling at the time.
I wouldn’t worry about it too much. Dark Matter and Dark Energy are still need to be explained, and the hierarchy problem isn’t going away anytime soon.
Aside from the content of the article (which people much more competent than I commented on), I’ve noticed that in form it was dumbed-down much more than I would expect in a Quanta article. All this baby talk about Chinese and Italian food, which as far as I can tell explains nothing, would not look out of place in mainstream media, if not Reader’s Digest, but not in Quanta…
On this background statements like “string theory has no free parameters” and “It doesn’t make sense to ask which string theory describes our universe, because there is only one” are especially puzzling. I wonder what he meant by this (if anything). My best effort in understanding the food analogy is that it tries to indicate that something like “all variants of string theory predict the same physical effects”, but since he himself implies that string theory does not predict any specific physical effects, I remain puzzled…
I’m actually rather encouraged about field moving toward it/qbit stuff. I think the chances of it leading to a TOE any time soon are pretty slim, but papers such as Witten’s expository one are rigorous, interesting to read, and connect with other disciplines. So as a taxpayer I’m getting some value from them. That was most assuredly not the case for 99% of what the field has produced over the past decade or two.
“It seems that Witten has taken up the study of quantum information theory”
It’s where the most funding is going to be available in the next 10-20 years. EU has provided a 20bn eur budget to fund quantum information science in that period, while China has a couple of orders of magnitude more than that — they already have a satellite in orbit, sending Bell pairs across continents and providing for quantum-crypto secure phone calls between China and Austria…
One would be stupid not to get string theory into the mix for a piece of the pie, regardless of any actual or potential “radical new framework” stuff. People who give the money won’t recognize any lack of content anyway.
But I’m completely baffled that Witten actually wrote a 30+ page recap of stuff that is readily available in textbooks, and written by actual experts on quantum information theory. What is he trying to achieve with that?
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Witten is lecturing at the PITP school this summer, I assume this document was prepared for that purpose. Also, best way to learn a subject is to write about it…
He also recently wrote this other expository article:
I doubt that funding has much to do with his getting interested in this, he’s someone whose research will get funded if he wants, whatever he is doing.
Dijkgraaf on the other hand has for many years not been doing much research, his main activity now is fund-raising. I think his writings for the public should be seen in that light: he would like to get people to believe that all is well with HEP theory, so that they can be more readily convinced to fund it.