Theorists with a Swamp, not a Theory | Hacker News Reader

Theorists with a Swamp, not a Theory

math.columbia.edu

30 pointschmaynard15 comments

Anyone have insight into how theoretical quantum field theory is developing outside of string theory? Not just high energy physics but also condensed matter physics. I'd imagine understanding quantum field theory more deeply leads to more efficient modelling and computation, but that sort of incremental advancement doesn't get much public exposure.

The breadth of your question makes it difficult for any one person to give a representative answer. I'll give a few examples, biased by my limited background.

1. Amplitudology: https://www.quantamagazine.org/physicists-discover-geometry-...

2. Conformal bootstrap: https://www.quantamagazine.org/using-the-bootstrap-physicist...

3. Tensor networks: https://arxiv.org/abs/1306.2164

Well yea, of course. It was an open invitation :) thanks for replying!

I'd say all three of these are topics related to string theory and worked on by string theorists. I don't think of them as part of string theory exactly, but it's roughly the same set of people doing the research. What does that mean? The two possibilities that occur to me are a) that the age when one could make a career purely as a string theory specialist is ending, and b) that knowing string theory is a competitive advantage for anyone doing formal theory.

I would say that all three of those topics are being worked on by researchers who have also worked on string theory (among many other people), but string theory is not directly relevant to most of the work in those topics. Especially tensor networks, which is largely driven by condensed matter physics and thus far has limited relation to string theory. Eg: most of the research at the interface between tensor networks / high-energy physics is restricted to a particular tensor network known as MERA, and its association with holographic spacetime [1].

If I might make a sociological observation, people who work on "string theory" have had to do the hard work of understanding quantum field theory in its many contortions, and the "good researchers" among them often have a thorough understanding of a good chunk of ideas in fundamental physics and related math. This also puts them in a position to capitalize on any related research avenues which they consider promising, even if those topics have little to do with string theory as such. So, IMHO (b) definitely carries weight, and I do not have a complete enough picture to comment on (a).

[1] PS: I have worked on this topic. Also, FWIW, I wouldn't claim to have a string theory background, but I did learn a little string theory in grad school.

I enjoy Peter Woit's writing and especially loved his book "Not Even Wrong." I also enjoy shitting on string theory from the comfort of my armchair. Maybe this is "productive," in the sense that getting people to stop investing in string theory will get them to work on investing in something else, but again from my armchair, I just don't see what positive work is happening. It feels like there are not enough holes in the standard model that need plugging and no big theory trying to supplant it or handle gravity gaining ground.

I think there's an unexamined assumption that a "theory of everything" must exist.

As it stands now we don't have a working theory of the turbulent motion of fluids. We don't know why hurricanes and eddies happen, but we're investing brainpower in understanding particle physics in a neighborhood of the big bang? Get out of here.

It must exist because we still haven't reconciled quantum mechanics with relativity. That matters if we ever want to understand what happens inside black holes, or the moment of the big bang itself. As of right now, our physics literally breaks, it stops working. If a black hole was a computer program, we'd get a critical systems fault the moment it began running.

“Theory of everything” is a bit of a misnomer. Rather, the goal is to understand the fundamental laws of nature. That doesn’t mean all problems about complex, composite systems like turbulence will be solved. Think about it like finding the underlying simple rule of a cellular automaton, as opposed to all the phenomena such a rule gives rise to. Sometimes the fundamental is more simple than what emerges from it.

His book contains several factual inaccuracies that he either has failed to correct or refuses too (as of last year). It makes me think a lot less of him and his position on string theory. It makes me wonder what else has he misrepresented in his criticisms.

Keep in mind science is not free of "agendas"; people in competing areas love to bash the competition because they're competing for funding, aka their livelyhood.

care to share some of the inaccuracies?

Can you point me to something about these inaccuracies?

Bored medieval philosophers speculated on how many angels could dance on the head of a pin. Bored modern philosophers peculate on string theory. Neither put forth experimentally testable hypotheses, so one is about as scientific as the other.

I suppose that's true in some sense, but at least string theorist have done some interesting math?

(It may not be math that applies to the real world, but math being math is eternally valid as long as the axioms hold... and sometimes you get surprising applications later on.)

Well, if angels are physical in the slightest, modern philosophers have computed an upper bound of how many of them could dance on the head of a pin, before they collapse into a black hole

Reply on news.ycombinator.com