Short Galileo Quotes

There’s a reason for this. Curiosity is unruly. It doesn’t like rules, or at least, it assumes that all rules are provisional, subject to the laceration of a smart question nobody has yet thought to ask. It disdains the approved pathways, preferring diversions, unplanned excursions, impulsive left turns. In short, curiosity is deviant. Pursuing it is liable to bring you into conflict with authority at some point, as everyone from Galileo to Charles Darwin to Steve Jobs could have attested.

With the best of intentions, the generation before mine worked diligently to prepare their children to make an intelligent case for Christianity. We were constantly reminded of the superiority of our own worldview and the shortcomings of all others. We learned that as Christians, we alone had access to absolute truth and could win any argument. The appropriate Bible verses were picked out for us, the opposing positions summarized for us, and the best responses articulated for us, so that we wouldn’t have to struggle through two thousand years of theological deliberations and debates but could get right to the bottom line on the important stuff: the deity of Christ, the nature of the Trinity, the role and interpretation of Scripture, and the fundamentals of Christianity. As a result, many of us entered the world with both an unparalleled level of conviction and a crippling lack of curiosity. So ready with the answers, we didn’t know what the questions were anymore. So prepared to defend the faith, we missed the thrill of discovering it for ourselves. So convinced we had God right, it never occurred to us that we might be wrong. In short, we never learned to doubt. Doubt is a difficult animal to master because it requires that we learn the difference between doubting God and doubting what we believe about God. The former has the potential to destroy faith; the latter has the power to enrich and refine it. The former is a vice; the latter a virtue. Where would we be if the apostle Peter had not doubted the necessity of food laws, or if Martin Luther had not doubted the notion that salvation can be purchased? What if Galileo had simply accepted church-instituted cosmology paradigms, or William Wilberforce the condition of slavery? We do an injustice to the intricacies and shadings of Christian history when we gloss over the struggles, when we read Paul’s epistles or Saint Augustine’s Confessions without acknowledging the difficult questions that these believers asked and the agony with which they often asked them. If I’ve learned anything over the past five years, it’s that doubt is the mechanism by which faith evolves. It helps us cast off false fundamentals so that we can recover what has been lost or embrace what is new. It is a refining fire, a hot flame that keeps our faith alive and moving and bubbling about, where certainty would only freeze it on the spot. I would argue that healthy doubt (questioning one’s beliefs) is perhaps the best defense against unhealthy doubt (questioning God). When we know how to make a distinction between our ideas about God and God himself, our faith remains safe when one of those ideas is seriously challenged. When we recognize that our theology is not the moon but rather a finger pointing at the moon, we enjoy the freedom of questioning it from time to time. We can say, as Tennyson said, Our little systems have their day; They have their day and cease to be; They are but broken lights of thee, And thou, O Lord, art more than they.15 I sometimes wonder if I might have spent fewer nights in angry, resentful prayer if only I’d known that my little systems — my theology, my presuppositions, my beliefs, even my fundamentals — were but broken lights of a holy, transcendent God. I wish I had known to question them, not him. What my generation is learning the hard way is that faith is not about defending conquered ground but about discovering new territory. Faith isn’t about being right, or settling down, or refusing to change. Faith is a journey, and every generation contributes its own sketches to the map. I’ve got miles and miles to go on this journey, but I think I can see Jesus up ahead.

Many people today acquiesce in the widespread myth, devised in the late 19th century, of an epic battle between ‘scientists’ and ‘religionists’. Despite the unfortunate fact that some members of both parties perpetuate the myth by their actions today, this ‘conflict’ model has been rejected by every modern historian of science; it does not portray the historical situation. During the 16th and 17th centuries and during the Middle Ages, there was not a camp of ‘scientists’ struggling to break free of the repression of ‘religionists’; such separate camps simply did not exist as such. Popular tales of repression and conflict are at best oversimplified or exaggerated, and at worst folkloristic fabrications (see Chapter 3 on Galileo). Rather, the investigators of nature were themselves religious people, and many ecclesiastics were themselves investigators of nature.

U.S. launch vehicles are these days too feeble to get such a spacecraft to Jupiter and beyond in only a few years by rocket propulsion alone. But if we’re clever (and lucky), there’s something else we can do: We can (as Galileo also did, years later) fly close to one world, and have its gravity fling us on to the next. A gravity assist, it’s called. It costs us almost nothing but ingenuity. It’s something like grabbing hold of a post on a moving merry-go-round as it passes—to speed you up and fling you in some new direction. The spacecraft’s acceleration is compensated for by a deceleration in the planet’s orbital motion around the Sun. But because the planet is so massive compared to the spacecraft, it slows down hardly at all. Each Voyager spacecraft picked up a velocity boost of nearly 40,000 miles per hour from Jupiter’s gravity. Jupiter in turn was slowed down in its motion around the Sun. By how much? Five billion years from now, when our Sun becomes a swollen red giant, Jupiter will be one millimeter short of where it would have been had Voyager not flown by it in the late twentieth century.

Many of the important principles in twentieth century physics are expressed as limitations on what we can know. Einstein's principle of relativity (which was an extension of a principle of Galileo's) says that we cannot do any experiment that would distinguish being at rest from moving at a constant velocity. Heisenberg's uncertainty principle tells us that we cannot know both the position and momentum of a particle to arbitrary accuracy. This new limitation tells us there is an absolute bound to the information available to us about what is contained on the other side of a horizon. It is known as Bekenstein's bound, as it was discussed in papers Jacob Bekenstein wrote in the 1970s shortly after he discovered the entropy of black holes.

This is an empirical claim: Look closely enough at your own mind in the present moment, and you will discover that the self is an illusion. The problem with a claim of this kind, however, is that one can’t borrow another person’s contemplative tools to test it. To see how the feeling of “I” is a product of thought—indeed, to even appreciate how distracted by thought you tend to be in the first place—you have to build your own contemplative tools. Unfortunately, this leads many people to dismiss the project out of hand: They look inside, notice nothing of interest, and conclude that introspection is a dead end. But just imagine where astronomy would be if, centuries after Galileo, a person were still obliged to build his own telescope before he could even judge whether astronomy was a legitimate field of inquiry. It wouldn’t make the sky any less worthy of investigation, but astronomy’s development as a science would become immensely more difficult. A few pharmacological shortcuts exist—and I discuss some of them in a later chapter—but generally speaking, we must build our own telescopes to judge the empirical claims of contemplatives. Judging their metaphysical claims is another matter; many of them can be dismissed as bad science or bad philosophy after merely thinking about them. But to determine whether certain experiences are possible—and if possible, desirable—and to see how these states of mind relate to the conventional sense of self, we have to be able to use our attention in the requisite ways. Primarily, that means learning to recognize thoughts as thoughts—as transient appearances in consciousness—and to no longer be distracted by them, if only for short periods of time. This may sound simple enough, but actually accomplishing it can take a lot of work. Unfortunately, it is not work that the Western intellectual tradition knows much about. LOST

In many fields—literature, music, architecture—the label ‘Modern’ stretches back to the early 20th century. Philosophy is odd in starting its Modern period almost 400 years earlier. This oddity is explained in large measure by a radical 16th century shift in our understanding of nature, a shift that also transformed our understanding of knowledge itself. On our Modern side of this line, thinkers as far back as Galileo Galilei (1564–1642) are engaged in research projects recognizably similar to our own. If we look back to the Pre-Modern era, we see something alien: this era features very different ways of thinking about how nature worked, and how it could be known. To sample the strange flavour of pre-Modern thinking, try the following passage from the Renaissance thinker Paracelsus (1493–1541): The whole world surrounds man as a circle surrounds one point. From this it follows that all things are related to this one point, no differently from an apple seed which is surrounded and preserved by the fruit … Everything that astronomical theory has profoundly fathomed by studying the planetary aspects and the stars … can also be applied to the firmament of the body. Thinkers in this tradition took the universe to revolve around humanity, and sought to gain knowledge of nature by finding parallels between us and the heavens, seeing reality as a symbolic work of art composed with us in mind (see Figure 3). By the 16th century, the idea that everything revolved around and reflected humanity was in danger, threatened by a number of unsettling discoveries, not least the proposal, advanced by Nicolaus Copernicus (1473–1543), that the earth was not actually at the centre of the universe. The old tradition struggled against the rise of the new. Faced with the news that Galileo’s telescopes had detected moons orbiting Jupiter, the traditionally minded scholar Francesco Sizzi argued that such observations were obviously mistaken. According to Sizzi, there could not possibly be more than seven ‘roving planets’ (or heavenly bodies other than the stars), given that there are seven holes in an animal’s head (two eyes, two ears, two nostrils and a mouth), seven metals, and seven days in a week. Sizzi didn’t win that battle. It’s not just that we agree with Galileo that there are more than seven things moving around in the solar system. More fundamentally, we have a different way of thinking about nature and knowledge. We no longer expect there to be any special human significance to natural facts (‘Why seven planets as opposed to eight or 15?’) and we think knowledge will be gained by systematic and open-minded observations of nature rather than the sorts of analogies and patterns to which Sizzi appeals. However, the transition into the Modern era was not an easy one. The pattern-oriented ways of thinking characteristic of pre-Modern thought naturally appeal to meaning-hungry creatures like us. These ways of thinking are found in a great variety of cultures: in classical Chinese thought, for example, the five traditional elements (wood, water, fire, earth, and metal) are matched up with the five senses in a similar correspondence between the inner and the outer. As a further attraction, pre-Modern views often fit more smoothly with our everyday sense experience: naively, the earth looks to be stable and fixed while the sun moves across the sky, and it takes some serious discipline to convince oneself that the mathematically more simple models (like the sun-centred model of the solar system) are right.

The model favoured by Schreck, one that had been in existence for some forty years, placed the planets in orbit around the sun, and the sun and moon in orbit around the earth. Complex though this was, it appeared to a majority of astronomers the one that best corresponded to the available evidence. There were some, however, who preferred an altogether more radical possibility. Among them was a Czech Jesuit, Wenceslas Kirwitzer, who had met Galileo in Rome, and then sailed with Schreck to China, where he had died in 1626. Prior to his departure, he had written a short pamphlet, arguing for heliocentrism: the hypothesis that the earth, just like Venus and the other planets, revolved around the sun.24 The thesis was not Kirwitzer’s own. The first book to propose it had been published back in 1543. Its author, the Polish astronomer Nicolaus Copernicus, had in turn drawn on the work of earlier scholars at Paris and Oxford, natural philosophers who had argued variously for the possibility that the earth might rotate on its axis, that the cosmos might be governed by laws of motion, even that space might be infinite. Daring though Copernicus’ hypothesis seemed, then, it stood recognisably in a line of descent from a long and venerable tradition of Christian scholarship. Kirwitzer was not the only astronomer to have been persuaded by it. So too had a number of others; and of these the most high profile, the most prolific, the most pugnacious, was Galileo.

The swing of a pendulum may be long or short, but as long as it swings, it invariably measures the same amount of time.

Nearly forty years later, while Galileo was employed as the First and Extraordinary Mathematician of the University of Pisa and Mathematician to His Serenest Highness, Cosimo II, the Grand Duke of Tuscany, he wrote a short essay on gambling “in order to oblige him who has ordered me to produce what occurs to me about the problem.”17 The title of the essay was Sopra le Scoperte dei Dadi (On Playing Dice). The use of Italian instead of Latin suggests that Galileo had no great relish for a topic that he considered unworthy of serious consideration. He appears to have been performing a disagreeable chore in order to improve the gambling scores of his employer, the Grand Duke.

In order to exemplify the way in which a soul seeks to actualize itself in the picture of its outer world — to show, that is, in how far culture in the "become" state can express or portray an idea of human existence — I have chosen number, the primary element on which all mathematics rests. I have done so because mathematics, accessible in its full depth only to the very few, holds a quite peculiar position amongst the creations of the mind. [...] Every philosophy has hitherto grown up in conjunction with a mathematic belonging to it. Number is the symbol of causal necessity. Like the conception of God, it contains the ultimate meaning of the world-as-nature. [...] But the actual number with which the mathematician works, the figure, formula, sign, diagram, in short the number-sign which he thinks, speaks or writes exactly, is (like the exactly-used word) from the first a symbol of these depths, something imaginable, communicable, comprehensible to the inner and the outer eye, which can be accepted as representing the demarcation. The origin of numbers resembles that of the myth. Primitive man elevates indefinable nature-impressions (the "alien," in our terminology) into deities, numina, at the same time capturing and impounding them by a name which limits them. [...] Nature is the numerable, while History, on the other hand, is the aggregate of that which has no relation to mathematics hence the mathematical certainty of the laws of Nature, the astounding Tightness of Galileo's saying that Nature is "written in mathematical language," and the fact, emphasized by Kant, that exact natural science reaches just as far as the possibilities of applied mathematics allow it to reach.

Consider this famous passage from Galileo: Shut yourself up with some friend in the main cabin below decks on some large ship, and have with you there some flies, butterflies, and other small flying animals. Have a large bowl of water with some fish in it; hang up a bottle that empties drop by drop into a wide vessel beneath it. With the ship standing still, observe carefully how the little animals fly with equal speed to all sides of the cabin. The fish swim indifferently in all directions; the drops fall into the vessel beneath; and, in throwing something to your friend, you need throw it no more strongly in one direction than another, the distances being equal; jumping with your feet together, you pass equal spaces in every direction. When you have observed all these things carefully (though doubtless when the ship is standing still everything must happen in this way), have the ship proceed with any speed you like, so long as the motion is uniform and not fluctuating this way and that. You will discover not the least change in all the effects named, nor could you tell from any of them whether the ship was moving or standing still Galileo’s point is that the absolute velocity of a system of bodies is not detectable by any means available to a scientist who is part of that very system, because the relative motions of the bodies are unaffected by their overall velocity. Only by relating the bodies to some external system can the motion be detected

In the case of Newtonian physics, velocity boosts—transformations where all bodies are increased in speed by the same amount, in the same direction—are, provably, symmetries. And so Galileo is right: velocity boosts are undetectable in Newtonian mechanics. The postulate that velocity boosts are symmetries is called the principle of relativity. In popular culture it is of course associated with Albert Einstein, but the basic idea is hundreds of years older. And it creates a potentially severe problem for Newton’s physics: it tells us that, contra Newton’s suggestion, it is in principle impossible, according to physics itself, to detect whether or not something is moving with respect to the rest frame.