# What is the quantum path?

## What is the quantum path?

The path integral formulation of quantum field theory represents the transition amplitude (corresponding to the classical correlation function) as a weighted sum of all possible histories of the system from the initial to the final state.

**Who invented path integrals?**

One usually refers the Feynman’s concept of path integral to the work of Norbert Wiener on Brownian motion in the early 1920s.

### Are path integrals 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. But the real problem is that, many people do not know they are doing handing waving when they are doing it.

**What is a propagator in quantum mechanics?**

In quantum mechanics and quantum field theory, the propagator is a function that specifies the probability amplitude for a particle to travel from one place to another in a given period of time, or to travel with a certain energy and momentum.

#### What is the difference between line integral and path integral?

A line integral (sometimes called a path integral) is the integral of some function along a curve. One can integrate a scalar-valued function along a curve, obtaining for example, the mass of a wire from its density. One can also integrate a certain type of vector-valued functions along a curve.

**What are path integrals used for?**

Path integrals are used in a variety of fields, including stochastic dynamics, polymer physics, protein folding, field theories, quantum mechanics, quantum field theo- ries, quantum gravity and string theory. The basic idea is to sum up all contributing paths.

## Is spacetime a Euclidean?

The geometry of Minkowski spacetime is pseudo-Euclidean, thanks to the time component term being negative in the expression for the four dimensional interval. This fact renders spacetime geometry unintuitive and extremely difficult to visualize.

**What is the purpose of a line integral?**

A line integral is used to calculate the surface area in the three-dimensional planes. Some of the applications of line integrals in the vector calculus are as follows: A line integral is used to calculate the mass of wire. It helps to calculate the moment of inertia and centre of mass of wire.