Three Scientific Revolutions: How They Transformed Our Conceptions of Reality (6 page)

Following the sighting in 1604 of a brilliant nova, there was an event in 1609 that would soon transform the entire conception of the universe. Galileo had always exhibited a great curiosity in machines, along with a skill for inventing and using instruments, such as calculators, calibrators, quadrants, even constructing a number of compound microscopes and engaging an instrument maker to live with his family to assist him in his constructions. Thus when occupying the Chair of Mathematics in Venice at age fortyfive and hearing a “rumor” of a Dutch instrument called a “spyglass” that brought distant objects closer by magnifying them, it aroused his usual curiosity. As he later wrote in the
Sidereus Nuncius
(The Sidereal Messenger, translated as Starry Messenger):

About 10 months ago a rumor came to our ears that a spyglass had been made by a . . . Dutchman by means of which visible objects, although far removed from the eye of the observer, were distinctly perceived as though nearby. . . . This . . . caused me to apply myself . . . to investigating the principles and figuring out the means by which I might arrive at the invention of a similar instrument, which I achieved shortly afterward on the basis of the science of refraction. And first I prepared a lead tube in whose ends I fitted two glasses, both plane on one side while the other side of one was spherically convex and of the other concave. Then, applying my eye to the concave glass, I saw objects satisfactorily large and close. Indeed, they appeared three times closer and nine times larger than when observed with natural vision only. . . . Finally, sparing no labor or expense, I progressed so far that I constructed for myself an instrument so excellent that things seen through it appear about a thousand times larger and more than thirty times closer than when observed with the natural faculty only.
²³

His first lunar observations were made in December of the same year followed by vivid drawings the following March in the
Sidereus Nuncius
of the phases and irregular surface of the moon showing its pits, mountain ranges, and ravines that he interpreted as evidence of rivers, lakes, and seas. The drawings so clearly resembled the earth that they caused a sensation. Having experienced the videos of astronauts landing on the moon and the recent discoveries of the surface of Mars by the rover Curiosity, it is difficult today to appreciate the shock of those comparisons, since they completely undermined the ancient distinction between the celestial and terrestrial worlds. This was the first
observational evidence
contesting it!

Galileo also included his citing of the “four little stars” circling Jupiter and what are now known as the “rings of Saturn,” but that he described as “two opposite protuberances resembling ears,” along with the phases of Venus predicted from the heliocentric but not the geocentric system, further opposing the latter. Because it was a defining characteristic of the ethereal realm that it was eternally unchanging, these new appearances also were shocking and threatening to the established cosmology.

Yet perhaps even more astonishing was his telescopic disclosure of the seven stars known as the Pleiades, along with many other fixed stars that had never been sighted with the naked eye. Because they showed no evidence of parallax (indicating the
decreasing
displacement of distantly moving objects the further away they are) implying they were much farther away and that the universe was much more expansive than previously thought. This could even challenge the spherical nature and alleged finitude of the universe. Galileo mentions these implications, but because Giordano Bruno was burned at the stake in 1600 by order of the Holy Office for his heresy in advocating an infinite universe similar to that of Epicurus and adamantly denied the right of the inquisitors to decide what counted as heresy, he did not press the argument.

As these observations obviously conflicted with Aristotle's cosmological view, the latter's followers concocted explanations to discredit the evidence, such as declaring that it was an artifice of the lenses, that the “spyglass” was only effective when used on the earth, or that despite appearances the moon was covered by a transparent crystalline sphere. One is apt to forget how rigidly authority was accepted at the time, both that of the Catholic Church and that of Aristotle. The Aristotelian Cesare Cremonini refused to look through the spyglass on the grounds that the evidence could not be true because it was not mentioned in any of Aristotle's works. Galileo's reply was that it was “as if this great book of the universe had been written to be read by nobody but Aristotle, and his eyes had been destined to see all for posterity.”
²⁴

Undaunted by these arguments and confident of the soundness of his evidence, he wrote in the
Sidereus Nuncius
:

By oft-repeated observations . . . we have been led to the conclusion that we certainly see the surface of the Moon to be not smooth, even, and perfectly spherical, as the great crowd of philosophers have believed about this and other heavenly bodies, but, on the contrary, to be uneven, rough, and crowded with depressions and bulges. And it is like the face of the Earth itself, which is marked here and there with chains of mountains and depths of valleys. (p. 40)

Initially the Catholic Church had supported his telescopic discoveries. In 1611 the prestigious Jesuit School, the Collegio Romano, authenticated his observations and he was inducted into the distinguished Accademia dei Lyncei where, after a banquet in his honor, the name
occhilai
or spyglass was replaced by
telescopium
, according to Stillman Drake. Later, during one of his visits to Rome he was honored by two popes, Pope Paul V assuring him “that he knew of Galileo's integrity and sincerity,” and that “so long as he lived . . . Galileo remained secure” (p. 256). Even his successor, Pope Urban VIII (later his livid accuser of duplicity), was such an ardent admirer that when sent a copy of
Il Saggiatore
(The Assayer) he had even written a poem in his honor.

But as his controversial discoveries continued and his disagreements with both the Aristotelians and the ecclesiastical authorities over the interpretation of natural phenomena increased, so did the hostility. For example, when the Aristotelians explained the amount of support water gave to floating objects as due to their shapes, in contrast to Archimedes' principle of specific gravity, Galileo published a reply entitled (in translation),
Discourse on Bodies on or in Water
, supporting Archimedes. In 1612 he entered into a dispute with a Jesuit mathematician named Christopher Scheiner (who wrote under the pseudonym Apelles) over the nature of the recently cited dark spots circling the sun. Scheiner argued that they were tiny stars similar to the four stars circling Jupiter, while Galileo, based on their formation, maintained they were like clouds circling the earth. Again challenging the distinction between the celestial and terrestrial worlds, this proved quite contentious (today sun spots are explained as magnetic fields that emit massive bursts of energy that appear as dark areas on its surface).

Then in a famous “Letter to Castelli” written on December 21, 1613, he openly expressed his disdain for those ecclesiastical authorities who rejected his discoveries because they conflicted with traditional biblical beliefs. Conceding that regarding questions concerning salvation and faith there was no higher authority than Holy Scripture, he adds that

I should think it would be prudent if no one were permitted to oblige Scripture . . . to sustain as true some physical conclusions of which sense and demonstration and necessary reasons may show the contrary. . . . I do not think it is necessary to believe that the same God who has given us our senses, reason, and intelligence wished us to abandon their use, giving us by some other means the information that we could gain through them. . . . (p. 226)

Though a rationally sound objection, the clergy considered it not only as a rejection of the heavenly nature of the universe, but also as contesting the authority of scripture and the Church itself, a crucial turning point in his relation with the Church. The following year on December 21 a fiery young Dominican named Tommaso Caccini “denounced from the pulpit of Santa Maria Novella the Galileists, and all mathematicians along with them, as practitioners of diabolical arts and enemies of true religion” (p. 238). About the same time, the cardinals of the Inquisition started examining Galileo's writings to see if they contained heretical material. Hoping to defend himself, he journeyed to Rome at the end of 1615 but with little success.

A commission of theologians was formed in February of 1616 that decided against the motions of the earth and the centrality of the sun, instructing Cardinal Bellarmine to inform Galileo of its decision, after which he was told to abandon those suppositions. Bellarmine met with Galileo on February 24 before a notary and a witnesses, leaving a notarized but unsigned record stating, in the words of Drake, that he “told Galileo of the official findings against the motion of the earth and stability of the sun,” while the commissary of the Inquisition “admonished Galileo in the name of the pope that he must not hold, defend, or teach in any way, orally or in writing, the said propositions on pain of imprisonment. Galileo Agreed” (p. 253). This is crucial in connection with his final trial and conviction in that Galileo
did agree
“not to hold, defend, or teach in any way, orally or in writing the motion of the earth and stability of the sun.” An edict was then dispensed proscribing all books purporting to reconcile Christianity with heliocentrism, though none of Galileo's were included. Finally, in 1992, the Catholic Church acknowledged that Galileo was correct and it was wrong.

Then in the fall of 1618 the citing of three comets again evoked the question of the reality of the distinction between the celestial and terrestrial worlds depending on the location of the comets, the distinction that previously had been raised by Galileo's lunar observations. Orazio Grassi (writing under the pseudonym of Lothario Sarsi of Siguenza), a well-known astronomer and critic of Galileo's observations, argued that because there was no evidence of parallax (again no change in the position of the stars as one moved) nor of enlargement, they must be in the translunar world and thus should have caused no opposition on the part of Galileo. But because Grassi's (or Sarsi's) argument embraced Tycho Brahe's modified geocentric view that the sun, encircled by the planets, revolved around the central Earth, Galileo dismissed it because of its asymmetry. In his rebuttal he not only ridiculed Tycho's system, he also mocked the distinction between the two worlds so cherished by the Aristotelians and the Christians, declaring “[n]ever having given any place in my thoughts to the vain distinction (or rather contradiction) between the [terrestrial] elements and the heavens . . .”
²⁵
(brackets added).

His second reply to Grassi in the
Il Saggiatore
(or The Assayer) written in 1623, is extremely important because it contains a further crucial revision of the traditional worldview. Drawing a sharp distinction between the ordinary sensory world and the independent micro-mechanistic world whose particles, being devoid of sensory qualities, were defined in terms of measurable physical properties, such as mass, motion, shape, and size, this would greatly contribute to the transition to Newton's corpuscular-mechanistic cosmology whose reality and exact nature posed the central problem of science and philosophy during the following three centuries.

I know of no previous or even later analysis to match Galileo's meticulous justification of the distinction, in section xlviii of
Il Saggiatore
, by analyzing the nature and origin of sensory qualities. While we normally distinguish pains and tickling sensations as being obviously subjective, we think of colors, sound, tastes, hardness, and heat as residing in the objects surrounding us independently of their being perceived. But having learned more about how dependent these latter sensory experiences are on our sense organs, nervous system, and the brain, Galileo argued that they too should be considered as subjective. But as previously indicated, how neurophysiological processes in the brain create the perceptual world as we experience it is still one of the greatest (if not
the
greatest) mysteries confronting us.

Both scientists and philosophers talk as if the ordinary perceptual world, being dependent on our brains, exists in our brains.But does that really make much sense, any more than saying it exists in the pineal gland, as René Descartes held? Certainly the Apple® computer I am using in composing this does not simply exist in my brain, nor does the car I get into and drive, the apartment I live in, the wife I live with, or the body I have. If my body exists in my brain because it is perceived, then since my brain is part of my body it, too, must exist in the brain, which does not make sense. Does the pistol someone uses to commit suicide exist in their brain? Did the nuclear disasters in Hiroshima and Nagasaki merely exist in people's brains?

Does it not make more sense to acknowledge that the world in which we exist, which includes colors, sounds, tastes, etc., is objectively real
within the conditions in which we experience it
, which seems to be true of the various dimensional contents of the universe as a whole? This does not preclude the necessity of revising our conception of this world, as in the Copernican revolution, but of recognizing the conditional status of all that is experienced and exists. This is the thesis I will be defending: that the universe consists of a seemingly endless series of objective contexts or conditions that is the destiny of scientists to explore and understand.

Galileo's justification of the distinction between the independent external causes of these sensory experiences and their modifications or additions due to their interaction with the human organism is clearly described. Though he discusses each sensory quality individually, I think the clearest general statement of his position is the following: