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.

I completely agree with you on this citation index business. They are totally silly. I also agree with the politics of theoretical physics. But Witten is Witten not only for h-index or politics (although they might have played a role). His abilities are unmatched in many many ways. He is undoubtedly a mathematical power house. His physical intuitions are legendary. Men are political animal and there is hardly any field where politics does not play any role. I see Witten as the greatest intellectual hero of our time because he is the most deserving. When Mandelstam was active he was unfortunate enough for not getting his due credit. But he is very old now and not active anymore.

Mandelstam is 80, give him a break, I really think he is the best of the best, and he needs a Nobel prize or something for what he did so tirelessly for two decades while getting dumped on.

Witten is a great physicist, and I never speak ill of great physicists. I read his work and I think he is fantastic.

comment deleted

Witten has contributed extremely significantly to mathematics, but so did Candlin with the Berezin integral, and so did Berezin with the proto-SUSY, and most significantly Pierre Ramond, who created graded algebras. You can't forget Ramond. And Belavin, Polyakov, Zamolodchikov and Knizhnik, who quadruple-handedly founded one of the most active fields of mathematics. Witten too, and Witten's contributions are closer to the center of what mathematicians find interesting, but you see how the stupid politics gets in the way--- he is praised so much, you can't praise him as he deserves without feeling you are neglecting other people.

The problem with mathematics is that the evaluation of quality is often by human judgement, not by nature, and that can lead to politics too. That's also somewhat true in physics, but physicists have ways to get around that, by doing experiments, or by pretending to do certain experiments and then breaking our head to come up with an answer as to what happens. The mathematicians have their own "though experiment" solution benchmarks, these are famous conjectures.

Witten solved many interesting mathematical problems of great depth, and also formulated and solved many physical problems (one of my favorite works of his is the superconducting cosmic string paper from the mid 80s, another is a failed paper to try to solve the cosmological constant problem from the 90s, failed, but he gave it a major creative inspirational shot). But stop trying to rank people on a line, it's really stupid.

If there were such a line, Mandelstam would be on top, because he was first, and the first stuff is the hardest to formulate.




---

Witten did a history degree, then after graduation went into politics for a year or so. Then read a few books on physics over summer that were sufficient to get him onto a top physics graduate course. Wouldn't you say that level of talent is scary?

He knew exactly what he was doing, politically and also physics. He was the first physics to understand the political lessons of the 1960s (and also the mathematics). Witten had a physicist father, a General Relativist, and this is where he made his early major, major breakthroughs (the positive mass theorem the bubbles of nothing Schwarzschild instanton, the gravitational compactifications of supergravity), he certainly knew General Relativity and Quantum Mechanics since high school, perhaps earlier, maybe in middle school (once you learn calculus, some differential equations it's easy enough to learn the rest in high school), he studied on his own (like almost every other decent physicist), especially mathematics, in his college years, so he chose a bullshit major he could do in his sleep, but one he was genuinely interested in, because he GOT the politics of the 1960s, and he knew it was going to replace the staid Soviet/Eisenhower/De-Gaulle bureaucratic politics of the 1950s. He also just studied all the math he could, probably wanting to do pure math.

He did a bunch of politics and linguistics, but McGovern lost, and that meant it was going to be terrible in the US for a while longer (nobody guessed how long). Physics in 1972 was still very politically stagnant--- the field was split in two, S-matrix and field theory, everyone was stoned and nobody was calculating anything (in Feynman's words, from that era). Also, it had an atom-bomb stench, maybe that was a factor, maybe not. It certainly was for others back then, who refused to study physics because of the association with atomic bomb work.

Then in 1974 or so, it becomes clear this young Dutch guy named 't Hooft has renormalized gauge theory, and 't Hooft is producing monumental results left and right, on anomalies, instantons, new gauges, Feynman diagram summations, 2-d models, everything. When he sees this (and he saw it for sure) Witten immediately switches fields. He applies to a graduate program in applied mathematics where he knows David Gross is active (he has a plan), goes over to David Gross and talks physics to him, at which point Gross arranges for him to switch departments, and Witten is considered a phenom, because he already knows everything (it was a stupid trick in the print era-- if you just read the literature, and you look like a genius--- he was also a genius though).

Then he gets a PhD under Gross (who is by this time very famous, Gross knows S-matrix theory, he studied under Chew, but he is also a major leader in field theory, after asymptotic freedom, plus he knows condensed matter and does 2d stuff too, all things Witten expertly absorbed). He gets a job on the East Coast, at Harvard, where S-matrix and strings are taboo. Then he collaborates with all the big shots, Venziano, Coleman, and so on. Coleman is impressed to no end, and starts studying gravitational things in this era. (Witten is also doing great solo work at this point, like the nonabelian bosonization), and the endless schmoozing and obvious talent and knowledge pushes his h-index to the roof.

Then he goes to Princeton, where he switches and supports string theory, bringing every other marginalized voice up from the gutter, and now he is ABSOLUTELY UNTOUCHABLE, politically, he is Albert Einstein. One cannot thank him enough for this, it was the most important political move in physics history, and that's not an exaggeration. He also does amazing work to push string theory forward from this point on, formulating open string field theory, finding realistic compactifications, and finding subtle physical consequences of string theory which would give possible observational signatures. He also does amazing work in all fields of high energy physics, and has pure mathematics breakthroughs.

Witten, ignoring the politics, is the best physicist in the world, seriously, I don't know why the politics has to happen. It was obviously necessary in the 1970s, and 1980s, considering how awful the academic world was becoming, but it's no longer necessary now. People can't get away with stuff like they did back then.

---

Not my downvote, but Witten wasn't the creator of string theory, he was still a boy when it was formulated in 1968-1974: the creators were Mandelstam, Chew, Venziano, Fubini, Susskind, Thorne, Goddard, Olive, Scherk, Schwarz, Ramond, Neveu, Lovelace, Kaku, Kikkawa, and a lot of other people from the 1960s and 1970s, Witten got the field the attention it deserved, and pushed it forward with pioneering extending contributions in the 1980s and 90s, and until today. That's not a slight on him, but you can't blame him for string theory--- it's not the political winds that tell you if it is right, it is the theory and nature.

Even if string theory is wrong for our universe, it cannot be disproved mathematically, it is a consistent mathematical framework of quantum gravity, probably (but not yet certainly) the only such framework, and for this, it cannot ever lose importance, because we really had no clue before how to do this. A future idea will have to build on and link to string theory insights.

Further, it has an application in QCD and nuclear collisions, where it is an approximation to hadronic scattering which is correct in the ultra-confined limit, the limit you can't solve with perturbation theory diagrams.