Stationary phase approximation path integral

1. What is the path integral approach?
2. Is the path integral rigorous?
3. What is Euclidean path integral?
4. What is the stationary medium approximation?

What is the path integral approach?

The path integral is a formulation of quantum mechanics equivalent to the standard formulations, offering a new way of looking at the subject which is, arguably, more intuitive than the usual approaches.

Is the path integral rigorous?

It is indeed folklore that path integral is not rigorous mathematically, or more precisely, the rigorous maths has not yet been rigorously developed. This is typical in physics.

What is Euclidean path integral?

Euclidean Path Integral. The oscillatory nature of the integrand eiS/¯h in the path integral gives rise to distributions. If the oscillations were suppressed, then it might be possible to define a sensible measure on the set of paths.

What is the stationary medium approximation?

what is the stationary medium approximation? n_a'' = 0 and x_a<<1 (advection is neglected) For diffusion in a stationary medium, the species diffusion flux is equal to the absolute flux associated with transport of the species.