# What is the principle of least action? [duplicate]

I want to understand the principal of least action intuitively, away from any mathematical proof.

## marked as duplicate by Chair, Qmechanic♦ classical-mechanics StackExchange.ready(function() { if (StackExchange.options.isMobile) return; $('.dupe-hammer-message-hover:not(.hover-bound)').each(function() { var$hover = $(this).addClass('hover-bound'),$msg = $hover.siblings('.dupe-hammer-message');$hover.hover( function() { $hover.showInfoMessage('', { messageElement:$msg.clone().show(), transient: false, position: { my: 'bottom left', at: 'top center', offsetTop: -7 }, dismissable: false, relativeToBody: true }); }, function() { StackExchange.helpers.removeMessages(); } ); }); }); Sep 12 '18 at 14:46

• I'm removing the quantum mechanics tag because I believe that it's best understood in the context of classical mechanics/newton's laws and only later applied to QM. – Chair Sep 12 '18 at 13:09
• Possible duplicate of Why the Principle of Least Action? – Chair Sep 12 '18 at 13:10
• Note that your intuition may or may not have anything to do with my intuition. You say 'least action' and I see a fuzzy green carpet in my mind. – Jon Custer Sep 12 '18 at 13:24
• Are you familiar with Occam's razor? – Lewis Miller Sep 12 '18 at 13:35
• Is Feynman's take on this good enough to answer your question? feynmanlectures.caltech.edu/II_19.html – Farcher Sep 12 '18 at 14:43

What I mean by "least complicated" can be understood by an example: Suppose that a classical particle has to move inside an isotropic space from a point $A$ to a point $B$. Then according to the least action principle, it has to propagate on the straight line connecting these points. It must not follow any other way because it doesn't have to complicate things (since the space is isotropic for example).