And Yet it Moves…

May 12, 2009 § 1 Comment

Dialogues Concerning Two New Sciences (Galilei, Galileo)

There are some books that are significant because of the novelty of their content, others for originality of form; a third and rarer kind exists, that derive their significance purely from knowledge of the historical context in which they were written, and the profound influence they have had in the history of ideas.

This is one such book.

It was written in 1638, by an old man (Galileo was 74) on the verge of going blind, an insomniac who had been severely reprimanded, placed under house arrest and ostracized by the Church six years prior to this date, as a consequence, it was said, of his defence of the Copernican system in his book Dialogue Concerning the Two Chief Systems, but mainly, it is suspected, for his unflattering portrayal of Pope Urban VIII as a kind of buffoon in the book.

The "Tuscan Artist" of Milton's poem (Portrait by Giusto Sustermans, courtesy Wikipedia)

Galileo, broken but not crushed, wrote Two New Sciences in 1638 as his final offering to posterity: a summary of his entire scientific body of work over the previous 30 years. He avoids astronomy scrupulously, but breezily chats about motion, gravity, statics, projectiles and simple harmonic motion, with loads of geometry thrown in. He is clearly one of the first “moderns”, intoxicated by the beautiful idea of a physical reality that can be described entirely in mathematical terms – inclined planes, arcs of circles and directrices of parabolas. I think, upon reading this book, that we do not do him sufficient justice as a pioneering scientist. Note this nugget on Page 74:

I begin by saying that a heavy body has an inherent tendency to move with a constantly and uniformly accelerated motion toward the common center of gravity, that is, toward the center of our Earth…

So much for the apocryphal story about Newton and the apple! Or when Galileo states:

Furthermore we may remark that any velocity once imparted to a moving body will be rigidly maintained as long as the external causes of acceleration or retardation are removed…

… which of course is Newton’s first, minus the hoopla about inertia! One also gets fleeting and fascinating glimpses of the world-view of the man. There is some bitterness:

…for human nature is such that men do not look with favor upon discoveries – either of truth or fallacy – in their own field, when made by others than themselves. They call him an innovator of doctrine, an unpleasant title…and by subterranean mines they seek to destroy structures which patient artisans have built with customary tools.

But there is much humility as well – as in this quote, remarkably similar to the pebbles-on-a-beach statement of Newton’s:

Profound considerations … belong to a higher science than ours. We must be satisfied to belong to that class of less worthy workmen who procure from the quarry the marble out of which, later, the gifted sculptor produces those masterpieces which lay hidden in this rough and shapeless exterior.

Galileo couldn’t find a publisher willing to touch him in all Italy, such was the ubiquitous fear of incurring Papal wrath. He found a patron and publisher in faraway Netherlands, whence copies flew, within a generation, to Flanders, Germany, France and England. Perhaps this was part of an overall movement of the center of gravity in arts, sciences and commerce, from Italian cities to Western Europe. We know Descartes read him, knew what horrors Galileo was subjected to for speaking the truth, and so wrote his own “Discourse on Method” (of cogito ergo sum fame) with much trepidation, many misgivings and couched in several loud protestations of deep faith. We know John Milton thought the world of Galileo, meeting him near Florence around the time of publication of this book and incorporating a mention of the scientist in Paradise Lost (“…the Moon, whose Orb / Through Optic Glass the Tuscan Artist views“). And yet, beyond doubt, there was at least one other man who was significantly influenced by Galileo’s works, someone who, from a safe distance, was able to whip up the winds of scientific change that blew away the cobwebs of medieval superstition in a way that Galileo simply couldn’t.

On 8 Jan 1642, Galileo Galilei died in Florence. On Christmas Day the same year, a baby was born in Lincolnshire, England, and named Isaac Newton…and finally, then, there was Light.


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§ One Response to And Yet it Moves…

  • ravi says:

    Great commentary, but for the other side of Galileo’s story and the traditional version of his tribulations, I highly recommend Paul Feyerabend’s take on the affair (unfortunately misappropriated by Ratzinger).

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