What the hierarchy problem asks — why is gravity so much weaker than the other three forces

How many types of fundamental forces are represented in the Standard Model of particle physics and which gauge bosons mediate each of these forces?

Four fundamental forces: electromagnetic (photon), weak (W and Z bosons), strong (gluons), gravity (graviton, not yet confirmed)

What the electroweak unification achieved — Glashow, Salam, and Weinberg showed EM and weak force are one

Unified electroweak theory: EM and weak force as one interaction

Which gauge symmetry underlies the unification of the electromagnetic, weak, and strong forces at high energies, and how does it manifest in the Standard Model?

SU(2)xSU(3) gauge symmetry unifies forces in the Standard Model, manifesting as weak and strong interactions

What QCD (quantum chromodynamics) describes — the strong force between quarks mediated by gluons

QCD describes the strong force interactions between quarks via gluon exchange

What string theory proposes — fundamental objects are 1D strings vibrating in 10 or 11 dimensions

String theory posits fundamental objects as 1D strings in 10 or 11 dimensions

What the cosmological constant problem is — quantum field theory predicts vacuum energy 10^120 times too large

Quantum field theory overestimates vacuum energy by 10^120 times, causing the cosmological constant problem