Someone needs to defend string theory here. For one thing, it really is the only step beyond quantum field theory (the theoretical framework of the standard model) that actually works mathematically. And it contains gravity, along with all other types of force and particle observed. So it is still the best candidate for a theory of everything.
Part of what derailed string theory was actually an event in experimental particle physics - the discovery of the Higgs boson without any accompanying particles. Up until that point, theoretical physics had built up a certain paradigm for how to think about physics beyond the standard model. The nongravitational interactions would be unified in a "grand unified theory", and (slightly broken) supersymmetry would protect the Higgs boson mass from being massively increased by virtual particles. This paradigm is logically independent of string theory, but it was integrated into how string theorists think about reality, and in particular how "string phenomenologists" (the kind of people trying to identify which Calabi-Yau provides the shape of the extra dimensions) approach the task of applying string theory to reality.
The experimental evidence now tells us that this paradigm is almost certainly wrong. But there is no consensus on what should replace it, and there is very little attempt to identify new paradigms that would naturally find a home in string theory. String phenomenologists are still mostly looking at supersymmetric grand unification, and the string theory elders are pursuing topics in quantum gravity which are unlikely to yield empirical payoffs any time soon.
This comment section indicates that skeptics of string theory have won the battle for Internet public opinion. But smart money should bet on a revival of string theory once fruitful new paradigms are found.
Part of what derailed string theory was actually an event in experimental particle physics - the discovery of the Higgs boson without any accompanying particles. Up until that point, theoretical physics had built up a certain paradigm for how to think about physics beyond the standard model. The nongravitational interactions would be unified in a "grand unified theory", and (slightly broken) supersymmetry would protect the Higgs boson mass from being massively increased by virtual particles. This paradigm is logically independent of string theory, but it was integrated into how string theorists think about reality, and in particular how "string phenomenologists" (the kind of people trying to identify which Calabi-Yau provides the shape of the extra dimensions) approach the task of applying string theory to reality.
The experimental evidence now tells us that this paradigm is almost certainly wrong. But there is no consensus on what should replace it, and there is very little attempt to identify new paradigms that would naturally find a home in string theory. String phenomenologists are still mostly looking at supersymmetric grand unification, and the string theory elders are pursuing topics in quantum gravity which are unlikely to yield empirical payoffs any time soon.
This comment section indicates that skeptics of string theory have won the battle for Internet public opinion. But smart money should bet on a revival of string theory once fruitful new paradigms are found.