Here within the lacking part of ultimate theory, i.e. the Scale-Symmetric Theory, we derived the fundamental equation of the Matrix Quantum Mechanics i.e. the commutator. It follows from the phase transitions of the non-gravitating Higgs field (of the inflation field) that are based on the half-integral-spin constancy. The fundamental equation results from the quantum entanglement that leads to the infinitesimal transformations. In reality, the Matrix Quantum Mechanics that describes excited states of fields (i.e. the quantum particles) is timeless and non-local i.e. non-deterministic. But the Matrix Quantum Mechanics leads to the time-dependent, so deterministic, wave functions that are characteristic for the Statistical Quantum Mechanics. It is the reason why the wave functions appear in the equations of motion. The Statistical Quantum Mechanics or the Quantum Theory of Fields, are the semiclassical/semi-quantum theories. The presented here extended Matrix Quantum Mechanics leads to the methods applied in the Quantum Theory of Fields but there appear some limitations. The idea of existence of many separated parallel worlds is incorrect.