The 2020 Physics Nobel Prize was announced this morning, with half going to Roger Penrose for his work on black holes, half to two astronomers (Reinhard Genzel and Andrea Ghez) for their work mapping what is going on at the center of our galaxy. I know just about nothing about the astronomy side of this, but am somewhat familiar with Penrose’s work, which very much deserves the prize.
Penrose is a rather unusual choice for a Physics Nobel Prize, in that he’s very much a mathematical physicist, with a Ph.D. in mathematics (are there other physics winners with math Ph.Ds?). In addition, the award is not for a new physical theory, or for anything experimentally testable, but for the rigorous understanding of the implications of Einstein’s general relativity. While I’m a great fan of the importance of this kind of work, I can’t think of many examples of it getting rewarded by the Nobel prize. I had always thought that Penrose was likely to get a Breakthrough Prize rather than a Nobel Prize, still don’t understand why that hasn’t happened already.
Besides the early work on black holes that Penrose is being recognized for, he has worked on many other things which I think are likely to ultimately be of even greater significance. In particular, he’s far and away the person most responsible for twistor theory, a subject which I believe has a great future ahead of it at the core of fundamental physical theory.
In all his work, Penrose has shown a remarkable degree of originality and creativity. He’s not someone who works to make an advance on ideas pioneered by others, but sets out to do something new and different. His book “The Road to Reality” is a masterpiece, an inspiring original and deep vision of the unity of geometry and physics that outshines the mainstream ways of looking at these questions.
Congratulations to Sir Roger, and compliments to the Nobel prize committee for a wonderful choice!
Peter, a data point. About two decades ago, students requested that Roger Penrose give a physics colloquium at MIT, but they were vetoed by the faculty there, who thought his talk would be too fringe or non-mainstream
I saw someone speculate on Twitter that this may be a reaction to regret among the Nobel Academy that they didn’t give Hawking a Prize.
When I read the news that he had jointly won this morning I just immediately thought how right it was that he should win. I don’t know the rules around the prize, but he richly deserves an award for the singularity theorems, and as you say his other work (one day I will try, again, to get my head around twistors: there must be better resources on them now than there were in the 1980s) as well.
This is not to sneer at the other two recipients: the kind of experimental work which has gone on around GR since I stopped trying to be an academic is just heroic I think.
But the news made my day, anyway.
The Penrose-Hawking theorems were the main reason astronomers stopped deluding themselves that singularities were avoidable. No-hair theorems did not exist yet. (To be fully truthful, they don’t really exist to this day.) Big Bang models at the time were along the lines of Gamow’s Ylem. If you wanted to be sophisticated then, you did something like Lifshitz’s linearized perturbation calculations that incorrectly ignored self-gravitation.
Lars Onsager got the Chemistry Nobel; his Ph.D. is technically in chemistry from Yale, where he was a postdoc (actually accidentally predoc) and they suggested he use one of his published papers, but he did new research instead, on periodic solutions ofthe Mathieu equation. At the time none of the chemistry or even physics faculty at Yale could decide whether to award a Ph.D. for this, so they took it to the mathematics department who said that they would award a Ph.D. for it if nobody else did.
So Lars Onsager, got the Chemistry Nobel (but really for physics) while holding a Chemistry Ph.D., which was really a Mathematics Ph.D. (in sheep’s clothing).
Andrew P. Mullhaupt,
Thanks, I didn’t know the Onsager story. Too bad his prize wasn’t for his solution to the 2d Ising model. Then the first prize in mathematical physics would have been a prize in Chemistry to a Chemistry Ph.D….
From the Nobel prize press release about the massive object at the center of our galaxy: “Around four million solar masses are packed together in a region no larger than our solar system.” The Schwarzchild radius of the sun is about 3km, so for 4 million solar masses we have a Schwarzchild radius of 12 million km. This is much, much smaller than our solar system (for comparison, the distance between the Earth and the sun is 150 million km).
So how do we know that this is really a black hole?
It is pretty clear to me why Penrose did not receive the breakthrough prize.
First couple of breakthrough prizes went to string theorists who then became members of the board that decides who gets the prize. Penrose has never been hiding his strong critique of strings (in books, interviews et.c.), so it adds up.
This news made me check if Roy Kerr was still alive. And indeed he is.
On the topic of the mathematical physics, I wonder if physicists know or care about Christodoulou and Klainerman’s work, which to me is one of the summits of the subject in the last fifty years.
The real question is why it takes about 55 years to give such an award? I remember first reading about Penrose (and Hawking) in MTW’s Gravitation book published in 1973. I realize it helps to have observational evidence of black holes, but I think this has been around for quite a while. I am glad that he lived long enough to get his recognition from the Nobel Committee.
Besides the question of the title of the PhD, is there any other example of a Nobel prize awarded for a theorem ? As a side question: what about the Fields Medal ? Was Penrose already to hold for it, or was not it considered as a mathematically significant enough result ?
I never expected Penrose to get a Nobel Prize, but am very glad that he did. A true original thinker!
martibal/Mark Weitzman,
I don’t know of another example of a theorem getting a Nobel Prize. Hawking I think never got a Nobel prize because Hawking radiation is all too testable in principle, but not in practice and the theorems with Penrose were theorems and thus not something testable about the real world.
One guess as to what’s going on here is that the lack of good new testable ideas about fundamental physics in recent decades has meant that if the Nobel committee wants to stick to rewarding only things that pass experimental test, then they will have to give awards to less and less impressive results. At some point the fact that they are ignoring hugely important ideas like those of Hawking and Penrose starts to become an obvious problem and perhaps this has caused them to rethink their criteria. In Penrose’s case, the fact that he has a hugely impressive other body of work gives a good reason to find something to give him the prize for, even if they need to fudge their usual criteria. Hawking unfortunately didn’t live long enough to take advantage of this.
Dear Professor Woit,
I think the comment about the prize being awarded for a theorem in mathematics is a mischaracterization. It is not at all about making a previously known physical result rigorous!
In those days most physicists (including for example John Wheeler) believed that the singularities of the Schwarschild and Kerr solutions were unphysical and were due to either a poor choice of coordinates or because of symmetries.
Penrose showed that singularities were inevitable and physical, at least in the sense that empirically verified equations predicted them in generic situations (not only in special, symmetric solutions).
Hence, Penrose radically changed the physical picture and he did it by proving a mathematical theorem!
Why doesn’t anyone read the advanced information on the website?
https://www.nobelprize.org/uploads/2020/10/advanced-physicsprize2020.pdf
Nobel prizes are not given for theories. They are given for fundamental discoveries. Even Einstein’s Nobel was for one of his ideas proven through experimentation.
Clearly it was Penrose’s 1965 paper which won him this year’s prize. Hawking would not have shared the prize even if he were alive. Penrose’s ideas came before Hawking’s. The Nobel does not award subsequent or derivative work.
I cannot speak for physics, but it seems sometimes a chemistry prize is awarded to X for being who he is. Perhaps Penrose got the prize because he is Penrose and nobody else is.
DS,
You won’t find me arguing for a rigid distinction between math and physics, or that proving a mathematical theorem about a set of equations can’t provide new insight into them that counts as “physics”.
I have mixed feelings tbh. I love Penrose’s work, but, like with Hawking’s theorems, rigorous experimental verification is almost impossible by the very nature of the topic. So why relax prize requirements decades after the theorems were first proposed? Perhaps it’s to benefit the very theories Penrose dubs ‘Fashion, Faith and Fantasy’. What’s to prevent work on inflation from being awarded next year? I hate to sound conspiratorial but I actually think it’s very likely to happen now.
Frankly, Penrose deserved a share of the Nobel prize for quasicrystals back in 2011. It’s really strange how it all turned out.
The problem is that the time gap gets so large that it’s more important than the science. The main work was done by Einstein, Hilbert and Schwarzschild. They died long ago. Hawking died in 2018. Why waiting 2020, if this old work deserved a prize? And why not Kerr, given that LIGO/Virgo see rotating black holes?
By the way, in 2017 Quanta Magazine published this interview with Andrea Ghez.
This seems to be the anti-symmetric analog of Witten’s 1990 Field’s Medal. Wasn’t the math community surprised to see a physicist win the medal, much the same as some in the physics community are surprised to see a mathematician win the Nobel?
Max Born was another recipient of the Nobel Prize in Physics with a Ph.D. in Mathematics. (Source: https://en.wikipedia.org/wiki/Max_Born)
I was also delighted that Roger Penrose was awarded, although I’m not familiar with the details of his work on black holes. I’ve read his book The Road to Reality over and over and I’m slowly beginning to grasp more and more of it. It’s totally fascinating!
According to the Nobel committee, this is the first time in history that GR is awarded (remember that Einstein was not awarded for GR but for his work on the photoelectric effect).
Besidess, I think that Penrose could as well have been awarded the 2011 Nobel prize in chemistry for his work on “Penrose tilings” which paved the way for the discovery of quasicrystals.
Eugene Paul Wigner was given the Nobel prize ”for his contributions to the theory of the atomic nucleus and the elementary particles, particularly through the discovery and application of fundamental symmetry principles.”
Formally, Wigner was a chemical engineer, whose thesis was Bildung und Zerfall von Molekülen (“Formation and Decay of Molecules”). However, Wigner education, thanks to the flourishing interaction between the mathematical and physical sciences at Göttingen around the 1920’s, is not easy to define him into simple categories such as theoretical/mathematical physicist or a pure mathematician. After his thesis with PhD work with Michael Polanyi, he was interacting with people ranging from Arnold Sommerfeld to David Hilbert. So regardless what his PhD was for, it’s still worth mentioning that group theory was the main reason for his Nobel prize.
In this sense, I consider his nomination as a recognition of representation theory in QM, even before gauge theories and the geometrical theory of p-bundles became widely recognized as the mathematical language of the fundamental interactions.
This besides Bohr calling it Gruppenpest.
PS: Pascal Jordan certainly was a founding member of QM and a high caliber mathematician, and I am sure he did not received a Nobel prize for reasons which the interested reader may find for herself by searching his biography, e.g., Bert Schroer’s https://arxiv.org/abs/hep-th/0303241
I agree that “The Road to Reality” is a masterpiece. In ploughing through it repeatedly over the years, I’ve learned more from it about a wider range of topics than any other math/physics book I can think of. (Although I hate his tensor diagrams!)
For those complaining that the Nobel committe changed its criteria, in 1999 T’Hooft and Veltman got the Nobel prize for showing the renormalizability of Yang-Mills theories and as far as I know you can’t experimentally verify if a theory is renormalizable. Also as far as I can tell https://webspace.science.uu.nl/~hooft101/gthpub.html they did not make any experimental predictions in the work that was awarded the prize. The quote is “for elucidating the quantum structure of the electroweak interactions in physics” and analogously Penrose elucidated the structure of general relativity, showing it generically produces singularities.
On the whole, asking for experimental verification on Penrose’s work is nonsensical. If you went inside an event horizon and never met a singularity, the truthness of the theorem remains, it simply means that in the real world either the energy condition is broken or general relativity is incorrect at a certain scale. Either of these breakdowns would be revolutionary. The prize is due to: “for the discovery that **black hole formation is a robust prediction of the general theory of relativity**.” It is a statement about general relativity as a theory, not about reality.
Pascal,
I believe the most conclusive evidence that Sag A* is a black hole is that orbital motions have been detected very close to the innermost stable orbit of the object if it is indeed a BH, and that these observations agree very closely with models of what I think are hot spots in the accretion disk. These orbits have periods of under an hour and velocities around 0.3c. ArXiv copy of the paper on this is here: https://arxiv.org/abs/1810.12641.
Apart from that, there’s the question that we don’t have any other candidates for anything that would pack 4 million Solar masses into something the size of the Solar system, I think.
I am a bit surprised so many people love “The Road to Reality”. For a book that is supposed to assume no prior knowledge of physics, I found it confusing and very dense. I came at it with a prior knowledge of physics and it took ideas which I previously understood and made them confusing. Possibly fun to look at things from a new perspective, but a lot of work to plow through when the end goal is twistor theory, which seems to be a Penrose pet project that no one else really uses. Possibly this book is like the Feynman Lectures, supposedly aimed at the neophyte but only really read by the experts looking for a novel approach. Is anyone aware of someone without a degree in physics who was actually able to get something out of this. Who is the intended audience? Maybe the next Penrose ?
I think it was Pauli who first used the expression “Gruppenpest”.
Laurence Lurio,
It’s definitely not a book for beginners. It is highly original: Penrose is doing things his way, not the way that is in most standard textbooks. This is confusing at first, he’s asking you to think about the subject of space-time geometry in a different way than you are used to. I’m sold on the twistor point of view, but even if you’re not, his way of thinking puts front and center the conformal geometry of Minkowski space, which is rather different than the usual way of thinking about space-time geometry, and often more enlightening. The work he got the Nobel prize for grew out of this point of view, showing the power of it.
I consider Penrose a fine visual artist, something I appreciate all the more because he is able to express his ideas so accessibly with pictures. I encountered the famous figure representing trapped surfaces many years ago and found it stirring. Likewise the Penrose diagram of a Kerr black hole (however unphysical, I’m not aware of a more concise description of how bizarre it really is). The only explanation of Twistors I’ve really been able to get my head around came from him: Start by imagining the dome of the heavens, full of stars…
I always admired Penrose most for communicating a highly original perspective that is nonetheless bracingly lucid and (perhaps deceptively) comprehensible. I’ve had similar feelings about Feynman’s popularizations. They both (I hope) helped me understand better how incredible advanced concepts in established physics can still be.
I don’t know who really “deserves” a Nobel Prize, but I’m very encouraged that he got it.
I’m curious where my countryman Roy Kerr fits in on the Nobel front. My understanding is that the Event Horizon Telescope data from last year confirmed his model of black holes, but this year’s prize is about black holes but not about the EHT data?
Like Penrose, Kerr’s no spring chicken. Hang in there, Roy!
I have no physics degrees. I loved “Road to Reality”. I did not *understand* everything in it, but it’s a large book and contained much that was interesting – more details than a popular science book, fewer than a graduate text. Feynman’s QED is the only similar, though more basic, book I can think of.
Matt,
It should be mentioned that your professional background is in geometry, which should have helped a lot to make the book accessible.
Peter, in 1997, out of curiosity, I went to the “Strings” Conference in Amsterdam. Hawking spoke with his computer voice. He said: “It is a pity that a black hole has not been found yet, because then I would get the Nobel prize.” He was really unlucky …
Jules,
I think to count as experimental vindication of Hawking’s work, you’d need not just finding a black hole, but observing Hawking radiation from it. That hasn’t happened yet, and I suspect is a very long time off. As Nicole above pointed out, the singularity theorem for black holes was due to Penrose, not Hawking, so the reason this award went to Penrose would not have worked to justify an award for Hawking.
Roger Penrose is certainly a brilliant mind, but why does he think that consciousness somehow arises from the quantum vibrations of microtubules? This I cannot fathom.
I am the neophyte Laurence Lurio can’t see. My degrees are in economics and management, which are juvenile and silly attempts at intellectual disciplines. I have no great talent for mathematics, though economics did give me the basics of linear algebra – although it isn’t much. For all that I found The Road to Reality, with four readings of all of it and quite a few more for several bits, completely fascinating, wonderful, illuminating, and all the rest. The sort of thing Penrose does is to offer me the clearest explanation I know anywhere for basics (like Goedels theorem – can’t remember whether that is in The Road or one of his others – doesn’t matter), and then those marvelous diagramatic explations of more complex material. This neophyte is happy.
The Penrose Singularity
A singular prize
For a singular role
A singular surmise
’bout a singular hole
Laurence Lurio: My physics class in college, back in 1977, used The Feynman Lectures. As far as I can tell, the real complaint about them is that while they give a good “big picture” perspective on the material and provide what I thought was excellent intuition, they don’t actually teach you how to solve the homework problems.
So possibly this is another instance of the “shut up and calculate” mindset.
Thanks Peter to praise Roger Penrose’s inspiring original and deep vision of the unity of geometry and physics. It’s worth emphasizing it indeed more explicitly than (but also be glad with) Sean Carroll in his recent tweet:
Roger Penrose is the first “theorist” to win for work in gravitational physics since — well, ever. Even Einstein won for quantized light, not general relativity.
(https://twitter.com/seanmcarroll/status/1313489948578902018?s=20)
Do you or does any commenter know any kind of theoretical physics progress or experimental evidence could bring the conditions to convince the Nobel committee that the discovery of a 125 GeV scalar boson at the LHC has something to do with the discovery that the Standard Model Lagrangian is a robust prediction of some advanced new spacetime geometric theory?
I would be interested to read an answer from @martibal for instance.
If some theoretical particle physicists at CERN would consider this naive question, the hope the Higgs boson has something to say about spacetime geometry could become less dark & the hope for a future award to the achievements of LHC phenomenologists & experimentalists could materialize, couldn’t they?
Incidentally a framework for unification of all fundamental interactions including gravity I have in mind happens to have a connexion with Penrose twistor theory (cf conclusion at p 578 of https://onlinelibrary.wiley.com/doi/epdf/10.1002/prop.201000069, also available on arxiv https://arxiv.org/abs/1004.0464).
It’s not clear Hawking could have won the Prize. His theorem is about cosmology. Penrose is an unexpected but appropriate choice, given how much evidence there now is for black holes. The pictorial breakthrough of Penrose diagrams and the interplay of timelike and spacelike regions are physics gold, for the ages.
Cedric Bardot,
About the Sean Carroll comment, I think he soon realized other theorists have gotten Nobel prizes for gravitational physics. The unique thing about Penrose is that this is an the award for mathematical physics.
The rest of your comment is off-topic, but thanks for pointing to the reference by Connes-Chamseddine to twistors. I’ve been trying to figure out if there is any relationship between the ideas about twistor unification I’ve been thinking about and the non-commutative geometry unification program, so this is helpful. But it has nothing much to do with Penrose, so off-topic here. I’ll surely be posting again about twistors and unification…
Since I was mentioned in a comment, I give a short answer: I do not think the way the Higgs field appears in the noncommutative geometry description of the standard model can be viewed as a “proof of the Higgs” similar to the “proof of black hole” by Penrose’s singularity theorem. It would be off topic to develop my point here, but I do not think the two situations are comparable.
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I take this occasion to ask once more if anybody knows how much mathematicians value the singularity theorems ? Penrose was in his thirties in 65, so still in the competition for a Fields medal. Not that prizes are so important, but in our math department in Genoa we have a course specially devoted to the singularity theorems (and we did not open it because of the Nobel prize !). So far it attracts more the physics students than the maths ones. In our university, mathematical physics seems to be more appealing to physicist than mathematician, although in Italy “mathematical physics” officialy exists as a sector of math (not of physics). I was wondering if this is a general situation, and if so, what can be done to “sell” the subject better to mathematicians ? Maybe the Nobel prize may have a pervert effect, convincing mathematicians that all this stuff has definitely more to do with physics than maths 🙂
martibal,
At the time Penrose did this work, interest of mathematicians in questions related to physics was at a minimum, so not surprising Penrose was not likely seriously considered for a Fields medal.
The situation now is quite different. Here at Columbia there is a great deal of interest in the mathematics of classical black hole solutions in the math department, less in the physics department. This is the specialty of one member of our department, Mu-tao Wang, and there has been an active seminar on the topic, see
https://sites.google.com/prod/view/grgas/home
A frequent visitor has been Princeton’s Sergiu Klainerman who also works on this, see
https://web.math.princeton.edu/~seri/homepage/seri.htm
Another prominent mathematician who works in this area is Shing-Tung Yau. To inspire mathematicians, one thing you could point to is this relatively recent conference
http://www.fields.utoronto.ca/activities/workshops/international-conference-black-holes
at the Fields institute.
Regardless of mathematicians’ attitudes to physics in the 1960s, I don’t think Penrose’s singularity theorem would have merited a Fields medal as such. Certainly his other work (the Penrose triangle!) wasn’t top of the world, however fascinating it was.
There was some awareness of mathematical physics at the highest levels back then. Laurent Schwartz received his 1950 Fields medal for developing and applying the theory of distributions, which made rigorous the Dirac delta-function. Not that the physicists were concerned, or even noticed.
As for Yau, his solution with Schoen of the positive mass conjecture (a significant foundational question for general relativity) was cited as part of his reason for receiving the Fields medal 1982. Their method of proof involved generalizing Penrose’s 1965 arguments from 1D to 2D.
Hawking’s extension of Penrose’s work to cosmology and the Big Bang was certainly pivotal in forcing cosmologists to accept it. As for black holes, Hawking’s area theorem has now been experimentally verified numerous times by LIGO.
For people interested in this, see the comments by David Wiltshire and also Roy Kerr himself on Peter Coles blog
https://telescoper.wordpress.com/2020/10/06/the-2020-nobel-prize-for-physics/#comments
I’m really happy that Penrose won this prize. I wrote an explanation of the theorem he proved, that won him the prize.
I’m curious what people here think about the effect, if any, of how the prize will affect teaching and research at the institutional level.
Specifically, will students consider Penrosian ideas (and others) more favorably as they plan their research, and will faculty appointments be weighted towards research related to the prize. Perhaps even a curriculum shift of emphasis. Or is the status quo going to continue.
DrDave,
I think that kind of effect of the Nobel exists, but is fairly marginal. The prize gives Penrose’s work more attention, but it was already well-known to people in the field. A good example of the effect might be that the prize announcement encouraged John Baez to write the really nice explanation that he links to above, so that gets more people aware of this.
My own agenda these days is to promote twistors, so it would have been great for me if Penrose got the award for twistors, but that’s not the case. On the other hand, most people seem to believe that Witten got the Fields medal for work on string theory, so maybe some day they’ll all believe that Penrose got the Nobel for twistors…