Here are three questions that appeared on Quora answered by Ron Maimon. Accurate or not, I still got the feeling he makes really good points.

First question: Who are some of the most underrated physicists?

The most underrated are those that contributed enormous things, but are not fully recognized for their contributions. This means, you probably never heard of them. I will focus on those theorists I know are shafted:

1. Ernst Stueckelberg: This fellow invented relativistic perturbation theory in 1934, almost 2 decades before Feynman and Schwinger. He discovered that positrons are back-in-time electrons in 1938 (and Feynman got the idea through Wheeler indirectly from him). Stueckelberg proposed renormalizable electrodynamics in 1941 but his paper was rejected from physical review, it took Hans Bethe’s 1947 Lamb-Shift estimate to reintroduce the subject. Stueckelberg should have recieved the 1965 Nobel prize along with Schwinger and Feynman, while Tomonaga could have shared his with Luttinger for 1d liquids (which is a bigger contribution of Tomonaga’s anyway). Stueckelberg didn’t rest on his laurels, he went on to discover the Abelian Higgs mechanism and the renormalization group too. Each of these are major discoveries in themselves, but to have one person discover all of them raises him to Bohr-Einstein status. He died insane and neglected, although he recieved some awards late in life. He is the godfather of underrecognized physicists, and he must by at the top of any list.

Why was he underrecognized? He was antisocial.

2. Alexei Starobinsky: This Russian fellow discovered inflation, Alan Guth was second. There is a lot of chauvanism in physics, and the great Soviet scientists were often neglected for no good reason. The mechanism was somewhat different, but the main predictions were the same, and the Soviet school calculated the fluctuations in CMB long before the famous inflation conference in 1983 reproduced their results (in a more primitive approximation, and with mistakes)

Why was he underrecognized? He was Soviet.

3. David John Candlin: this guy invented the Fermionic path integral, but credit accrued to Berezin, who wrote about it in a book a decade later. There is no dispute that David John Candlin is the inventor, his paper is a clear description of the anticommuting variables, reconstructing the state space, and producing the integral for them with the modern definition. Berezin was no slouch either, but he didn’t invent the thing. This is not an attempt to steal credit from Berezin, but to attribute the result properly: David John Candlin is the sole inventor. Everyone else in 1956 had the wrong idea, including Feynman, Schwinger, and Salam. David John Candlin is still alive, and lives in Edinburgh, so there might be time to get his historical perspective on those events.

Why was he underrecognized? He didnt publish a lot.

4. Stanley Mandelstam: This guy is certainly the greatest living physicist, although he is very old. In 1957, he discovered the double-dispersion relations, and essentially refounded S-matrix theory, which was proposed by Heisenberg in 1941, but lay dormant for nearly 20 years. This theory became string theory, after many twists and turns, and Mandelstam is the original formulator of 2-d conformal fields, fermionic correlation functions, string field theory, and the arguments for finiteness of string perturbation theory which convinced the world that the theory had no ultraviolet divergences. He also made pioneering contributions to field theory, and really, he deserves a major overdue Nobel Prize, but he’ll never get it.

Why was he underrecognized? He was too advanced for people to understand.

5. You can’t say Mandelstam without Geoffrey Chew. This fellow prosalytized for S-matrix theory so effectively, it dominated high energy physics from 1964 to 1974. He proposed that Regge trajectories describe hadronic physics, along with Frautshi, and Mandelstam’s theory of cross-channel high-energy/unphysical-angle relations gave the theory mathematical form. This is the birth of string theory. The string description of hadrons is underrecognized today.

Why was he underrecognized? He was not a formal wizard (unlike his collaborator Mandelstam), and people characterized him as a dimwit, ridiculously, since his physical intuition was spot on and now known to be more correct than that of Gell-Mann, Mandelstam, Weinberg, and other formal wizards. His phenomenonlogical calculations were also sound and competent.

6. Vladimir Gribov: Another S-matrix giant. This fellow gave form to Pomaranchuk’s idea that proton-proton and proton-antiproton collisions have equal cross sections at high energy, and predicted the Pomeron trajectory (attributed to Chew and Frautschi in the west, wrongly, although possibly independently). This prediction is stunning, and it is completely verified in the 1990s when proton anti-proton collisions at hundreds of GeVs showed that the cross sections do become equal. Did the S-matrix folks who predicted this in the early 1960s get a Nobel prize? No, they were booted out of academia, and mostly had to scrounge around in accelerators.

Why was he underrecognized? He was Soviet.

7. Tamiaki Yoneya: This obscure Japanese physicist was first to discover that string theory includes a graviton, a real graviton, not just a spin-2 particle that could be a graviton. He made the argument exceedingly elegant throughout the 1970s. He is still active in string theory today, and his underrecognition seems to be fixing itself.

Why was he underrecognized? He was a string theorist in the 1970s.

8. Joel Scherk: This guy is the godfather of modern physics. Although he is well known to string theorists, he is not well known enough, and he was driven to madness and possible suicide just before 1980, His death is mysterious, there are several conflicting reports, but his mental deterioration is well attested, and it is perhaps due to the fact that string theory was so thoroughly neglected in the 1970s.

Why was he underrecognized? He was insane. Also, string theorist in the 1970s.

9. Shoichi Sakata: Sakata proposed that hadrons are made of the proton, neutron and lambda. While this is incorrect in the details, the model works well, because these three particles are stand-ins for the up, down, and strange quarks, except with integer electric charges. His model was the direct precurser of the quark model, and is the reason that Gell-Mann and Zweig were able to formulate the correct theory independently. But he was first, and made a major contribution, if not the major contribution, to this idea.

Why was he neglected? He was a Marxist.

10. Pasqual Jordan: This guy co-discovered quantum mechanics, discovered Fermionic fields independently of Fermi, and made major contributions to early field theory.

Why was he neglected? He joined the Nazi party. This one I can sort of understand.

11. Iosif Khriplovich: This physicist discovered the negative beta function (asymptotic freedom) in nonabelian gauge theory in 1968-1969, three years before ‘tHooft discovered it (but Veltman did not allow him to publish), and five years before the pioneering papers by Coleman/Politzer and Gross/Wilczek that established the result for good. The Nobel prize to Gross Politzer and Wilczek should have gone to Khriplovich, who had a much more physical argument than a direct calculation with a finicky sign, he showed why the effect happens physically, that it is due to gluon polarization. David Gross is no slouch, he could have won for greater contributions, such as the heterotic strings, or the Gross Neveu model, or a host of things (he is really great), while Wilczek could have won for condensed matter anyons or the superconducting strong-matter high-pressure state (he also has great discoveries). The beta function was not the only great contribution Khriplovich made, he also discovered parity violating effects due to the weak interactions in atomic physics, and explained them as due to nuclear anisotropies interacting with the electron fluid. This research continues, and it is truly remarkable, considering the amount of speculation on P-violation in atomic physics in the 1980s, speculation which post-dated both Khriplovich’s theories and the experiments which verified them.

Why was he neglected? He was Soviet.

12. Robert Kraichnan: He is responsible for modern turbulence theory, including the inverse cascade in 2d. The inverse cascade is the prediction that turbulence in 2d takes small scale disturbances up to large scales, violating decades of physical intuition from 3d turbulence and the statistical ultraviolet catastrophe, it is truly a remarkable prediction. He is also responsible for many statistical physics models of turbulence, including the first “large N” approximation, something which took over physics when ‘tHooft discovered a more central high-energy version (although one can see Wigner and Dyson’s random matrix theory as another precursor to this). Anyway, he was working for decades on this, and recieved adequate support, so you can’t complain too much. But nobody read him.

Why was he neglected? He was not in academia.

13. Tony Skyrme: Tony skyrme discovered his eponymous model in 1960. It took a full 2 decades for this model to be rediscovered in large N QCD by Rajeev, Nair, Balachandran and then by Witten, and then he got some recognition, but promptly died. While trying to get a better handle on 4d Skyrmions in the 1960s, he also discovered the interpretation of 2d solitons like those in the sine-Gordon model as Fermions in a dual description, something which was refined by Coleman and Mandelstam in the mid 1970s into an exact identity of two dimensional field theories, the two dimensional bosonization/fermionization which is so central to physics today.

Why was he underrecognized? He was doing unfasionable unified field theoretical physics when simple particle models were in vogue.

14. Leo Kadanoff: He discovered the modern renormalization group, and the operator product relations which are central to determining critical exponents, work which was turned into an elegant 2d theory by Belavin, Polyakov, Zomolodchikov. He isn’t neglected anymore, but he was not awarded the Nobel prize with Kenneth Wilson (much to Wilson’s surprise), and he should have been (along with Wolfhardt Zimmermann, another neglected giant whose 1950s work was the true source of the operator product expansion, and which is now active mathematics, thanks to Connes and Kreimer). Kadanoff still keeps plugging away, and his stature keeps growing, so this is fixing itself.

Why was he negelected? Damned if I know. Perhaps that’s why he is neglected less and less with time.

And finally, I must end this list with a choice that is sure to be controversial, and is the most scandalous:

15. Martin Fleischmann: Having discovered the most suprising thing in the universe, namely that deuterated palladium sustains nuclear reactions, almost certainly of the deuteron-deuteron fusion sort, his reputation was scandalously

blackened, and his great work diminished, until his name became synonymous with fraudulent or delusional science. It is clear now, two decades later, than he was not delusional, but this realization came too late for Fleischmann, who was suffering from Parkinson’s disease at the end of his life. His memory drives one to work harder, with no hope of compensation, every day.

Why was he neglected? He was a chemist. Chemists are not allowed to discover fundamental challenges to all known nuclear physics, and his discovery stepped on well financed hot-fusion toes.

That’s the end for now. I could go on, because so many of the major discoveries in physics are scandalously underrecognized, Many of the physicists on the list who got some credit for the discoveries of others were still underrecognized for their own original contributions. There is not so much bad-faith— a lot of things were discovered simultaneously in ignorance of prior work— and the mechanism of credit accrual is mysterious and capricious, very rarely accruing credit to the proper author (but it happened: Einstein, Bohr, Heisenberg, Dirac, Feynman, Schwinger, Dyson, these folks got credit for their own original work) Attention to research was a scarce quantity in pre-internet times because it took decades to understand what the people were talking about. the Feynman’s and Schwinger’s of the world are an exception, not the rule. I hope people try to emulate the people on this list, not those that suppressed and heckled them.

I edited this for typos, included an extra neglected fellow, and added information on David John Candlin status.

Second question: Is Ed Witten really the world’s greatest living theoretical physicist?

I think the greatest living theoretical physicist is Stanley Mandelstam. His thinking and insights (usually with Chew) are the only reason there is such a thing as string theory. But this is just a stupid opinion, like “what’s your favorite pizza topping”.

Physics is not a sport, like chess, where you can be the best by winning. It is not a competition, or rather, the competition is against nature, and each discovery is a win where nobody loses. You discover stuff, and you tell people, and then you go discover something else. At the end of your life, if you’re lucky, like Ed Witten, or any of the other folks, you have at best a handful of discoveries compared to the size of the field. Then to ask who is greater, it’s a question of whether discovery X plus discovery Z is more important than discovery Y, which is completely inane.

Witten is a great physicist, and never speak ill of a great physicist. However, his number one position has been granted by a corrupt and wrong political process, similar to the h-index, and this is not an acceptable way to go about doing science. It turns a discovery art into a contact sport where the main activity is citation sowing and reaping. The people who win at contact sports are the ones that trample over the field and hurt others.

The physics h-index works like any other star-making procedure, you select a small basket of people to be famous, using early career competence as a test. Then you apply political selection on the famous folks after the fact to get the “best of the famous”. This process is bankrupt, because the best most original ideas come from absolutely nowhere, from the bottom of the barrel, from complete nobodies, just by the laws of statistics, because there are more nobodies than famous people. Nobody listens to these nobodies. In the old days, you needed people on top to endorse them, otherwise, they were just thrown out, like Everett, or the string theorists.

If you have famous people around, in the world before the internet, especially when hardly anybody could actually read the whole literature, like physics or mathematics in 1983, the famous people could sometimes get more famous by taking the work of a complete nobody, and republishing it as their own. In the early 1980s, nobody could read the whole literature, and you could get away with it, because nobody would know except for the author, and the author wouldn’t find a job, because people would assume that the nobody was plagiarizing the somebody, rather than the other way around. Of course this doesn’t work today. This type of corruption became worse during the reign of Ed Witten’s. Einstein, Feynman, Schwinger, ‘tHooft, Susskind always did stuff that was unmistakably completely 100% original, they never ever stepped on anyone else’s toes.

Since the process of making Ed Witten leader was political, one should describe how it works for future generations, so they will see how fragile pre-internet science was: the way you got more famous is by making famous research buddies who you cite, and pull up, and they pull you back, in a corrosive feedback process that requires a feedback amplificaiton mechanism to select a few people for the top, this is the h-index. This process of feedback citation marginalizes all really good people, because a person with a new idea is not going to get cited, they are going to be laughed at, no citations , then the idea suddenly becomes obvious, no citations again (Einstein’s Nobel prize winning photon paper has, like, 4 citations). This is not some weird exception, it is all the best work.

Ed Witten was transformational, because Ed Witten, through intelligence, foresight, and political shrewdness, made this horrific crappy system work pretty ok, at least throughout the 1980s and 1990s, by first rising to the top (quickly) through making the right friends and doing a bunch of competent field theory research with the right people, then once he got to the top, quickly recognizing and pulling up the RIGHT PEOPLE, the completely original people who were stomped on through the 1970s, the string theory people, and at the same time, all the while doing his own completely original work, which was unusually heavily mathematical, and pushed the field forward also. Ed Witten became a leader essentially because he was the only baby boomer on the East Coast physics departments who actually could read. He became a superstar when he endorsed strings, thereby giving East Coast journal people a way to check whether string papers are correct (ask Ed to referee it), and suddenly the field boomed, and everyone needed to make friends with Ed, because he was going to referee their string papers. Back then, people who weren’t John Schwarz or Michael Green couldn’t evaluate string papers.

The baby boomers had a drug catastrophe in the 1970s, which played a role in this. When people are burned out, they needed someone to follow in order to know what to do. Ed Witten played this leadership role in physics, emulating and displacing ‘t Hooft somewhat, who was the previous leader. I am trying very hard not to insult Witten here, rather to insult everyone else of his generation instead.

Third question: How does Edward Witten know so much math?

Researchers are expected to learn the stuff they need, and be familiar with everything. Since this is somewhat unrealistic, it just means you try to keep up all the time, and nobody feels they know enough, you always feel like you’re missing something.

Witten came before the internet, and one cannot overestimate how much more difficult it was to study mathematics back then. When you opened a math book, if you didn’t know the definitions, you couldn’t google them, you were just screwed. He studied mathematics (among other things) as an undergraduate, I remember he was grateful for the proper mathematics education he recieved, but he continued to read mathematics and internalize it also as a grad student and through his post doc and into his professorial career. He said he considered going into mathematics at one point, also perhaps linguistics at some other point. He was a young lefty in the 1960s, there were a bunch of exciting things to do, but he eventually decided that physics was where he would make the biggest impact. He was up to date on the mathematics of the 1960s, that’s extremely unusual for a pre-Witten physicist. Now, it’s expected, but it’s expected mostly because of Witten!

All physicists know the elementary mathematics curriculum, that’s no big trick. Most physicists have mathematical competence in the areas related to their chosen field, to the level of a beginning researcher. But what makes Witten special is his deep intuitive understanding of ALL fields of mathematics, especially deeply the 1960s topology stuff, that he clearly just learned for the heck of it, it wasn’t before useful in physics, all the homology, homotopy theory and algebraic geometry constructions mathematicians were doing back then. It became central with string theory.

For example, one of his famous works in the 1990s was a note identifying the structure of brane anti-brane annihilation as a type of K-theory, which is a Grothendieck construction which didn’t have a physical intepretation before, nor is it something you would expect any physicist would know about. Witten is the exception, because he knows the mathematics field as well as any mathematician, and he just likes the material, he reads it, and rediscovers large chunks for himself.

While it is not polite to speculate about people who are alive (you can just ask them), I suspect he learned a large chunk of advanced mathematics during his Harvard postdoc, in the late 1970s. Jaffe and Coleman are influenced by him, probably the influence goes both ways, Coleman begins doing topological instantons, then he did the vacuum decay work, the false-vacuum instanton thing which was so influential for inflation theory. Witten is also associated with two enormous Harvard pure-mathematics names, Bott and Yau. His mathematics had a Harvard feel to it, the 1985 Calabi Yau paper, the Morse theory paper, these are popular Harvard topics.

He won a fields medal, and this is for a beautiful interpretation of the Jones knot polynomial from large N 3d topological Chern-Simons gauge theory, a theory that he defined. In another related idea, just a few years ago, he showed with his student or postdoc that the volume conjecture (due to Thurston I think) is related to a property of these topological theories under analytic continuation, and modulo the standard problem of precisely defining the path integral, they gave what should be a proof of the conjecture. He has a bunch of recent mathematical work I couldn’t understand at all related to pure algebraic geometry.

He also has a bunch of non-mathematical physics work too which are famous classics, like the superconducting cosmic strings, the bubble of nothing instantons, the Witten anomaly, the Seiberg Witten theory and brane-stack constructions, the AdS/CFT constructions, a bunch more I probably forgot. One thing that is not considered a classic is a 1992 or 1993 cone idea about supersymmetry breaking that is very clever and simple idea for stabilizing the cosmological constant, but it probably doesn’t work (there seems to be a mistake, I don’t remember what I thought it was), but boy is it inspirational. it’s really intimidating, as all his work is of extremely high quality, and everything is for sure required reading. It is a little difficult to follow, because it requires knowing earlier physical and mathematical work, but it’s as if it was made for the age of the internet, because now you can learn the associated material without being in a fancy place.