David Madore's WebLog: Ex ungue Leonem

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Entry #0417 [older|newer] / Entrée #0417 [précédente|suivante]:

(Saturday)

Ex ungue Leonem

I forgot to record this here two days ago, but a great man came to Earth on December 25: arguably the greatest even, who would bring eternal Light to mankind.

I refer, of course, to Isaac Newton, who was born in Woolsthorpe, Lincolnshire (prematurely) on Christmas day of 1642, and of whom Alexander Pope would write—if sarcastically:

Nature and Nature's laws lay hid in night;
God said: Let Newton be!—and all was light.

Much is sometimes made of the fact that Newton was born on the very year that Galileo Galilei died, a broken man, in his home in Arcetri (near Florence): for in many ways did Newton vindicate Galileo and prove him right; the fact may even have been perceived by Newton himself. Unfortunately, it isn't true: Galileo died on January 8 of 1642 in the Gregorian calendar, which was then used in Italy, but this would have been December 29, 1641, in the Julian calendar, which remained in use in England until September 1752, and Newton's birth date is January 4, 1643 in the Gregorian calendar (so the time is not yet ripe to celebrate it).

Furthermore, Newton himself did not care so much for physics as his genius in the field is now recognized: it seems that he considered himself a mediocre physicist, a talented alchemist, and a theologian of great genius; certainly he was a mystic of a kind. Needless to say, this is not exactly what we now think of him: this brings a new twist to his famous saying,

I do not know what I may appear to the world; but to myself I seem to have been only like a boy, playing on the seashore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me.

It is also often pointed out that Newton's celebrated inverse-square law of gravitation had been, in fact, obtained (but probably not rigorously derived) by Robert Hooke in 1672, some time before Newton. I do not propose to revisit one the bitter scientific quarrels that set the Royal Society afire, nor that which opposed Newton to Leibniz as to who discovered calculus; nor do I wish to belittle the work of Christiaan Huygens, which in many ways foreshadowed Newton's own. Yet it can be said that, undoubtedly, the Philosophiæ Naturalis Principia Mathematica (1687) remain as a major landmark in mankind's scientific history, at par with very few others (such as perhaps Darwin's Origin of Species).

In 1696, Johann Bernoulli challenged the world's most able mathematicians of the time to solve the problem of the brachystochrone (finding the curve of fastest descent between two given points under gravity; the answer is a cycloid). Besides Johann Bernoulli's own, four other solutions were proposed: by Leibniz, Guillaume de l'Hôpital (Johann Bernoulli's student), Jacob Bernoulli (Johann's brother), and Newton. Newton solved the problem on the very evening that he received it, and published his solution anonymously; however, it was immediately recognized as being his: as Johann Bernoulli put it, ex ungue Leonem (you can tell the Lion by his claw).

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