# Lagrangian Action

1. Mar 2, 2005

### rayveldkamp

Hi, i've just started a course in Classical Mechanics, in 3rd year undergraduate physics, and i'm a bit confused as to what exactly an ACTION is.
All we've been told is that the action, S is defined as the integral from t1 to t2 of the Lagrangian with respect to time.

Ray Veldkamp

2. Mar 2, 2005

3. Mar 2, 2005

### rayveldkamp

Thanks for the help, i'm sure I'll have plenty more Classical mechanics questions this semester

4. Mar 2, 2005

### dextercioby

It is the essential functional in all theoretical physics...For discrete systems,it is indeed the integral of the function called LAGRANGIAN wrt time between specifed fixed limits.

Daniel.

Adn the extremum principle joining it is the fundamental principle in nature.

5. Mar 2, 2005

### Andrew Mason

The action is easy enough to define mathematically but its physical meaning is a very difficult thing to understand. I struggle with it. I would highly recommend Feynman's lecture - Chapter 19 in Volume II of The Feynman Lectures on Physics.

AM