When Social Distancing from the Plague Pays Off

It sure did for Sir Isaac Newton, this from The World of Mathematics:

Newton took his degree from Cambridge early in 1665.  In the autumn of that year the great plague, which was raging in London, caused the University to close, and Newton went back to live at the isolated little house at Woolsthorpe where he was born in 1642.  Here he spent most of his time until the spring of 1667, when the University reopened and he returned…Newton is throughout his life an enigmatic figure, but nothing is more extraordinary than his development in the period from 1663 to the spring of 1667…By the time of his return to Cambridge it is tolerably certain that he had already firmly laid the foundations of his work in the three great fields with which his name is for ever associated–the calculus, the nature of white light, and universal gravitation and its consequences.

Newton himself describes it in this way:

In the same year [1666] I began to think of gravity extending to the orb of the moon, and having found out how to estimate the force with which a globe revolving within a sphere presses the surface of the sphere, from Kepler’s rule of the periodical times of the planets being in a sesquialternate proportion of their distances from the centres of their orbs [sesquialternate means one and a half times, or, as we say, the square of the years are as the cubes of the orbits] I deduced that the forces which keep the planets in their orbs must be reciprocally as the squares of their distances from the centres about which they revolve: and thereby compared the force requisite to keep the moon in her orb with the force of gravity at the surface of the earth, and found them answer pretty nearly.  All this was in the two plague years of 1665 and 1666, for in those days I was in the prime of my age for invention, and minded mathematics and philosophy more than at and time since.

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