Subdivisions of string theory are completely misunderstood by critics

Tetragraviton wrote an insightful blog post

Most of String Theory Is Not String Pheno

where he tries to clarify some brutal misconceptions believed by Backreaction – as well as most laymen who read similar "sources" – about "what various string theorists actually do". He points out that Hossenfelder pretends to be a hero fighting against a powerful community, the string theory community, but in reality, she is only waging jihad against a small minority of the string community that is actually less numerous than groups such as the "loop quantum gravity fans" and others.

I completely agree with his main point.



This is the key pie chart that Tetragraviton has created. The string theory research has some vaguely defined parts. And because Hossenfelder considered "the research of less understood aspects of quantum field theory using string theory ideas" to be OK or a success, and this branch is actually a majority of the research – e.g. according to the pie chart that categorizes talks at the Strings 2015 annual conference, Hossenfelder is actually trying to fight against string cosmology and string phenomenology only, something that is researched just by more than a hundred of people.

Tetragraviton believes and I do believe that these subfields of string theory are actually understudied Cinderellas. They should be much larger than they are!




The pie chart has some problems. Many research projects can't be easily categorized. The percentages are inaccurate. Also, I am not sure where I would count all research on things like topological string theory, monstrous moonshine, and black hole information puzzle in string theory. Most likely, all these things belong to the "formal strings" slice (well, a part of the information puzzle would belong to "holography") which makes it even more insane how small this slice is.

(Update: I overlooked Tetragraviton's special group "Quantum gravity" where the black hole information loss issues clearly belong.)




Because of Maldacena's revolution and other things, the slices "holography" and "QFT" have grown a lot in the recent 20 years or so. Maybe the relative size of all the other subfields was basically constant. People keep on doing all these things. But because of the implications of string theory for quantum field theory, many string theorists began to do things that could be classified as "QFT", after all. The border between string theory and QFT has gotten blurred.

Much of this "QFT" work has only been reported at the string annual conference because either

1. the speakers used to be clear string theorists and still count themselves in this way, so their work was considered string theory because of the ad hominem arguments
2. some elementary ideas for studying quantum field theories in these ways came from string theory at the very beginning or they can be seen to be morally stringy a posteriori

These are very problematic reasons to count some research as "string theory". It's clearly just a matter of classification, terminology, convention, and sociology of conferences. But I think that most of this research – in the largest slice of the pie – shouldn't be considered string theory. Also, I think that an overwhelming majority of the "amplitudes" slice where Tetragraviton belongs (the light orange thin slice at the top) shouldn't be counted as a part of string theory. If something has no one-dimensional objects (strings) or an exact relationship (e.g. duality) with a theory that has these objects, it's simply not string theory. And if someone hasn't mastered the introductory courses or textbooks of the subject and has never written a string theory paper as defined in the previous sentence, he is not a string theorist. In particular, I think it's right to say that Tetragraviton is not a string theorist.

Maybe we should correct Tetragraviton: the likes of Hossenfelder try to assault not only string cosmology and string phenomenology but also formal string theory (where I would have counted most of the research from the times when I was publishing and surely most of the research that I am doing now and not publishing). But even these groups combined incorporate less than 500 active and paid researchers in the world.

Tetragraviton points out that the last String Pheno had 130 participants while the Loop Quantum Gravity conference had 190 participants. He makes a point I have made many times in the past: that it's actually much more sensible to compare loop quantum gravity to a subfield of string theory and not string theory as a whole and they're indeed comparable in size.

It's like the comparisons of Cuba or North Korea to the U.S. These small communist countries (Cuba is struggling to become a softcore, Obama-style communist country recently but let's ignore these "details") may claim to be the flagships of something really big. So North Korea or Cuba may defeat and mock the American imperialistic dwarfs, they assure their citizens in their propaganda outlets. However, a much better "counterpart" of Cuba is something like Florida and, you know, even Florida is much more important and much wealthier than Cuba these days (Florida's GDP is 11 times greater than Cuba's $80 million GDP). My point is that the boasting by folks in loop quantum gravity that they're "on par" with all of string theory is as silly as similar boasting by the leftover communist countries.

At the end, the crackpot community doing loop quantum gravity is actually more numerous than the set of string phenomenologists – the actual state-of-the-art experts who construct the most accurate and most complete theories or models of Nature. It's sort of scary – because what they have produced is clearly vastly less valuable and even vastly less extensive than the work by string phenomenologists (the gap is at least similar to the Florida/Cuba gap) – but it can't be surprising. The reason is simple. A majority of the people who can complete a college with some exact sciences in it has enough brainpower to do something like loop quantum gravity. But only hundreds or at most thousands of people in the world have enough brainpower to become string phenomenologists. The pool for loop quantum gravity folks is some 1,000 times larger than the pool for string phenomenology.

What's important is that the string phenomenologists are vastly more intelligent, vastly more caring about the evidence and all the details, results, calculations, and vastly more likely to learn whole new subfields of mathematics if they need them. They have also found many more real results. They are also surely more well-paid in average, by dozens of percent. But the income gap is dramatically lower than what it should be according to the meritocratic criteria.

I think it's unfortunate that there are only at most a "few hundred" people doing string phenomenology for the living in the world. It's equally unfortunate that the number of formal string theorists is just a little bit higher. If you estimate the size of these communities (including the stringy "quantum gravity") as 500 people and each of them gets some $200,000 a year in average including all the overheads and taxes, you will see that the mankind is really paying approximately just $100 million a year to extend its knowledge of physics at the true cutting edge. That's just a little bit more than one millionth of the world's GDP (which is approaching $100 trillion per year).

I just find it crazy for the mankind to pay just one millionth of its GDP to improve its understanding of the most fundamental laws of physics according to the most promising project to do so. And it's even more crazy that there are bullies and šitheads who would love to reduce this percentage further.