Wednesday, April 28, 2010

Newton's Third Law of Motion

If you are acquainted with the physical sciences, the Law of Attraction will be a familiar term to you. Among the first to describe this law was Sir Isaac Newton whose Third Law of Motion—the Law of Reciprocal Actions—appeared in his Philosophiae Naturalis Principia Mathematica, published in Latin in 1687. Here is a translation of part of Newton’s Third Law from Principia. I find it fascinating:

To every action there is always opposed an equal reaction: or, the mutual actions of two bodies upon each other are always equal, and directed to contrary parts. Whatever draws or presses another is as much drawn or pressed by that other. If you press a stone with your finger, the finger is also pressed by the stone. If a horse draws a stone tied to a rope, the horse (if I may so say) will be equally drawn back towards the stone; for the distended rope, by the same endeavour to relax or unbend itself, will draw the horse as much towards the stone, as it does the stone towards the horse, and will obstruct the progress of the one as much as it advances that of the other...This law takes place also in attractions...

Though we can’t see the effect of this law easily with the naked eye, nevertheless, if you push on a stone with your finger, the stone pushes back!

In other words, a force placed upon a physical body or entity will always be met with an equal and opposing force. Another way to put this is that a force attracts an opposing force. Likely this is where the concept “opposites attract” comes from.

I think of these opposing actions or forces like these two arrows pointing at each other:
This science, I believe, is at the root of the idea of the law of attraction.

: Newton’s understanding of this law was influenced by the earlier work of Galileo, Johannes Kepler, and others, and is further refined in his own law of universal gravitation (see S. Chandrasekhar, Newton’s Principia for the Common Reader, (Oxford: Clarendon, 1995) 370) and the work of later physicists.

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