Category Archives: Physics

Principle of Least Action (Part One)

Yes, we are lazy most of the time; we constantly persist in an inertial state of being, we tend to not strain ourselves in our daily actions, we incline toward alleviating either psychological or physiological effort or even both simultaneously, we prefer saving┬ánumbers to memorizing them, we prefer plugging digits into calculators to crunching them, riding to walking, screaming to reasoning, plunging to planning, common sense to scientific reasoning, “half-knowledge”* to “full-knowledge” and the rest… In response, our “elders” constantly nag at us and try to compel us to act against this innate inclination to slack-off — although they themselves may be staunch militants of the famous “Do as I say, not as I do”, which is in a way another form of the above described tendency. But what if I told you that this penchant has a foundation in both macroscopic and microscopic Physics?

First things first: after reading this post, don’t go running off to your parents and telling them that you won’t do your chores just because some quirky scientist on the Internet said that such laborious tasks will violate some LAW of Physics. “And we wouldn’t want that mum, would we?” Primo, it’s a principle not a law. Secundo, I’m not a scientist (not yet at least). And tertio, if necessary, I prefer the term “outlandish”. Having stopped that snowball from falling down the slope, let’s start by defining the “Principle of Least Action”. In layman’s terms, it is a principle that governs the action of a mechanical system, hence allowing scientists to foresee its motion, trajectory, etc. In this sense, a rope suspended by both ends takes on a shape corresponding to the minimal value of gravitational potential energy (GPE). In other words, its center of gravity will be at its lowest possible altitude in these conditions…

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