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How much progress actually happens in theoretical physics?
dscft116

Physics is incredibly precise (only pure mathematics is more rigorous) and everything does indeed follows from a small number of basic principles. These principles are not sacrosent though, more like useful assumptions, and in quantum gravity we don't expect locality to strictly holds. The solution of the black hole information paradox mentioned above is precisely showing that the late Hawking radiation (which is very far from the black hole) is the same quantum system as the black hole interior. This is a manifestion of quantum entanglement which is reali... (read more)

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How much progress actually happens in theoretical physics?
dscft*130

String theorist here. Progress has absolutely not stalled. The last big theoretical breakthrough was the AdS/CFT correspondence ( https://arxiv.org/abs/hep-th/9711200  ). This was our Transformers moment. This paper revolutioned the field, has now 20k+ citations, the most for any physics theory paper. It did completely solve the problem of quantum gravity for AdS spacetimes (negative curvature). There are too many things that have followed from this but I can give a few tidbits. For example it was understood that quantum black holes are the most chaot... (read more)

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ChristianKl102

The paper you linked about the last big breakthrough seems to be from 1997, so roughly 28 years ago. What do you consider to be the biggest breakthrough since then?

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1James Camacho
I might sound a bit daft here, but do theoretical physicists actually understand what they're talking about? My main concern when trying to learn is it feels like every term is defined with ten other terms, and when you finally get to the root of it the foundations seem pretty shaky. For example, the spin-statistics theorem says particles with half-integer spins are fermions, and full-integer spins are bosons, and is proved starting from a few key postulates: 1. Positive energy 2. Unique vacuum state 3. Lorentz invariance 4. "Locality/Causality" (all fields commute or anti-commute). The fractional quantum Hall effect breaks Lorentz invariance (1+1D universe instead of Lorentz' 3+1D), which is why we see anyons, so obviously the spin-statistics theorem doesn't always hold. However, the fourth postulate shows up everywhere in theoretical physics and the only justification really given is that, "all the particles we see seem to commute or anti-commute"... which is the entire point the spin-statistics theorem is trying to prove.