Stephen Weinberg on Understanding Quantum Mechanics

[vanhees71]

Ah, I see. However, the path-integral formalism is also no new theory or even interpretation. It's QT (including both non-relativistic "1st quantization" and relativistic QFT) but offers alternative analytical methodology to evaluate things. It's for sure, together with the invention of Feynman diagrams, among Feynman's most significant contributions to the methodology of theoretical physics.

 

[bhobba]

Ah, I see. However, the path-integral formalism is also no new theory or even interpretation.

The formalism isn't an interpretation - just the math expressed a different way.

However when people say its taking all possible paths at once it is an interpretation - the path is a hidden variable. Its very novel because the idea of actually taking every possible path at once is, how to put it it, rather unusual.

That said I am not terribly fussed about it - its just semantics which isn't really that important - its the math that is.

Thanks
Bill

 

[vanhees71]

What you indeed do in the path integral is to evaluate probability amplitudes in a specific way, i.e., by integrating over all possible trajectories in phase space, leading to the propagator.