Hello, could you tell me a bit about supersymmetry and what problems in physics could be solved? Thank you
Well, the original motivation was a problem called “the hierarchy problem” in physics. In a nutshell, the problem is that if we try and naively predict what the masses of the particles ought to be, by say, combining fundamental constants, we get a value on the order of the Planck mass, which is about 10^22 times heavier than an electron and is about 10^17 times heavier than the heaviest particles of all, like the top quark and the Higgs boson.
Supersymmetry was developed to “protect” the masses of the Standard Model particles by offering a method to cancel the heavy parts out: for each particle in the Standard Model there is a supersymmetric partner particle. If you hypothesize this, you don’t just get a more sensible prediction for particle masses, you also get a candidate dark matter particle (the lightest supersymmetric particle) and the coupling constants all meet at some super-high energy: a hint for grand unification.
Of course, that’s what’s appealing about supersymmetry. What’s not appealing is that the predicted masses of the supersymmetric particles are on the same order as the masses of the Standard Model particles, and we can definitively say that the LHC has ruled this out. In grand unification, the proton is unstable; many experiments have ruled that out. And the dark matter searches have been specifically searching for particles that would have the properties of the lightest supersymmetric particle, and have all come up empty.
So SUSY is a good idea that was worth exploring, and it could solve many problems if it were correct. But the evidence sure doesn’t point to it being correct.