Christina of Lorraine had astronomy questions for Fr. Benedetto Castelli, so she sat him down to get answers. The conversation occurred in December of 1613, and arguably Christina’s questions set the entire “Galileo Affair” into motion. Mario Livio opens his new book, Galileo and the Science Deniers, with that conversation between the mother of the ruler of Tuscany and one of Galileo’s friends. Livio says he wrote a book about Galileo because—
very few of the known biographies [of Galileo] were written by a research astronomer or astrophysicist. I believe, or at least hope, that someone actively engaged in astrophysical research can bring a novel perspective and fresh insights even to this seemingly overworked arena.
He also says he wrote it because he sees a connection between the Galileo story and the unscientific and anti-scientific attitudes present today in the broader world beyond working scientists (p. xv). Those are great reasons to write a book about Galileo. That broader world would surely benefit from a scientist’s look at Galileo’s work. Unfortunately, Livio leaves his scientist’s outlook elsewhere. Rather than providing a novel perspective, he re-tells an old tale that contributes to the very problem of science denial that he deplores in his book.
The problems with Galileo and the Science Deniers start in the first sentences of the book, with Christina and Castelli. Livio describes Christina questioning Castelli about the discoveries that Galileo had made since 1609 with his telescope, and pressing Castelli regarding whether the Earth moves, given that a moving Earth seems contrary to the Bible. Castelli, though intimidated by the prospect of arguing with royalty, politely and respectfully stands his ground. We know all this because Castelli described it all to Galileo in a letter of December 14, 1613, which still exists.
Christina of Lorraine is then the first in a long line of characters in Livio’s book who, for reason of what was in the Bible, opposed Galileo and his promotion of the heliocentric system of Copernicus. To Livio, Christina and company are Science Deniers who reject science for scripture. At one point (p. 115-116), Livio writes that such people—
were asking Galileo to give up convictions that had been forged on the basis of painstaking scientific observations and brilliant deductions, only because they appeared to contradict some ancient, vague, poetic texts—and only when those texts were interpreted literally rather than figuratively.... Should he have abandoned what he regarded as the only possible logical conclusions in favor of what amounted to a seventeenth-century version of political correctness?
Livio continues, noting that Galileo—
did his best to prove that, while interpretations of scripture could be reformulated in alternative ways so as to agree with what nature was presenting, facts were facts.
Yet, Christina of Lorraine and those of like mind did not disagree with the facts. Christina had a wingman in her conversation with Castelli—one Professor Boscaglia from the University of Pisa. Boscaglia emphasized to her that everything Galileo had discovered was true. However, he and Christina still both urged that the Earth does not move, both noting that a moving Earth is contrary to the Bible.
Livio relays all this. He describes how, following Galileo’s first publishing his discoveries in his 1610 Starry Messenger, some people did claim that Galileo was talking nonsense. Martin Horky, in particular, was most insulting in this regard. Yet by April of 1611 such claims were gone. A team of astronomers from the Society of Jesus verified Galileo’s discoveries, discoveries that showed that Jupiter had moons circling it, that Venus circled the Sun, and so on. Even Horky came around. Such is the power of reproducibility in science; everyone, even Horky, could eventually repeat Galileo’s observations and confirm his results.
But those observations of moons circling Jupiter, or Venus circling the Sun, did not show that Earth moved. Those discoveries were fully compatible with the ideas of Tycho Brahe, who Livio also discusses. Brahe envisioned the Sun, Moon, and stars circling an immobile Earth, while the planets circled the Sun. Tycho’s geocentric system and Copernicus’s heliocentric system were mathematically and observationally identical, insofar as the Sun, Moon, and planets were concerned.
Therefore, Christina and Boscaglia could accept that everything that Galileo had discovered was true—facts were indeed facts, after all—but not accept the Earth’s motion. They were not Science Deniers. The existence of Jupiter’s moons had been established through reproducible observations; Earth’s motion had not. Meanwhile, the Bible says (Eccl. 1:5),
The sun rises and the sun goes down; then it presses on to the place where it rises.
That might be poetic, and it might be ancient, but it is not vague. Sure, one might say that the Bible just speaks to things as we see them—after all, we do in fact see the Sun rise in the East, set in the West, and rise again in the East. But absent compelling argument for Earth’s motion, Christina, who Livio describes as a “singularly religious woman” (p. 148), would have no reason to prefer a less literal interpretation of the Bible.
Meanwhile, there were certainly compelling arguments for Tycho’s ideas.
Livio mentions the case of Cesare Cremonini, a staunch defender of the ideas of Aristotle. Cremonini, says Livio, refused to as much as look through a telescope. He was an atheist, so the words of the Bible would not have concerned him. But, as Livio reports (p. 98),
Cremonini wanted something deeper than what had been revealed by Galileo’s observations. He noted, for instance, that if the Moon was indeed a terrestrial-like body, as Galileo’s findings had implied, it should have fallen toward the Earth.
In terms of the scientific knowledge of the time, Cremonini was right. Terrestrial bodies fall down, they do not hang in the sky. Drop or throw a rock; it falls to Earth. The physics of the time, which was the geocentric physics of Aristotle, explained the motions of celestial bodies by assuming they were made of a substance not found on Earth, a substance that naturally stayed up in the heavens and moved in circles, as opposed to a rock which naturally fell toward the center of the Earth and stopped. Livio understands this, writing—
In the absence of a theory that could explain why this was not happening (a situation that lasted until Newton [decades after Galileo]), Cremonini was not prepared to give up Aristotelian views.
There were no physics to explain the motion of either the Moon or the Earth in the heliocentric system. By contrast, in Tycho’s system, the basic geocentric structure of Aristotelian physics remained intact. Tycho said that his system violated neither the laws of physics nor the words of the Bible.
Physics was one compelling argument for Tycho’s system. Another was the stars. In Tycho’s system the stars lay just beyond Saturn, whereas in the heliocentric system, they had to be very distant in order to explain why Earth’s motion was not reflected in them. But, as Livio writes (p. 65), given that vast distance,
one could then estimate the size that the stars had to be in order for them to be seen with their apparent dimensions observed with the naked eye. Those expanses turned out to be even larger than the diameter of the entire solar system, which seemed highly implausible. Consequently, Brahe concluded that the Earth could not be orbiting the Sun.
By contrast, in Brahe’s system stars were of reasonable size, comparable to the Sun and larger planets. Unfortunately, Livio presents this star size argument, but he never discusses it further. He just states that,
[Galileo] concluded that the apparent dimensions of stars as seen with the naked eye did not represent real physical sizes—they were just artifacts.
And here Livio fails to provide the broader world with a scientist’s perspective and insight; he leaves be the scientific problem of star sizes. In fact, while Galileo thought that the apparent dimensions of stars as seen with the naked eye did not represent real physical sizes, he thought that their apparent dimensions seen with the telescope did. He reported on those dimensions in various works that Livio cites: the sunspots letters, the reply to Francesco Ingoli, the Dialogo. Other astronomers, such as Simon Mayr, who Livio discusses, noted the telescopic dimensions of stars and the problems they posed for heliocentrism. Christoph Scheiner, another astronomer in Livio’s book, succinctly put it this way: if the orbit of the Earth cannot be detected in a heliocentric universe, but the size of a star can be, then the star must be larger than Earth’s orbit. Brahe’s stars problem did not go away; indeed, it was reinforced by the telescope.
Thus there were scientific arguments against heliocentrism that made the geocentric Tychonic system compelling. Scientists such as Mayr and Scheiner embraced that system, rejecting Earth’s motion, just like Christina of Lorraine. The reader might hope that a book written by an active scientific researcher would explore what these scientists had to say, discuss the dynamism and complexity of the scientific arguments of the time, and help the reader understand those arguments—but Galileo and the Science Deniers does not do that. Indeed, Livio portrays Mayr as not even understanding what Jupiter’s moons were (p. 69)—
Mayr may have independently detected the satellites [of Jupiter] before Galileo, but he failed to understand that the moons were orbiting the planet.
But Mayr certainly did understand that. He himself reported that—
by degrees [I] arrived at the following view, namely, that these stars moved round Jupiter, just as the five solar planets, Mercury, Venus, Mars, Jupiter, and Saturn revolve round the Sun.
In fact, Mayr was able to show mathematically that the observed motions of the moons indicated that Jupiter circled the Sun and not the Earth. Yet Livio misses this and misrepresents Mayr’s views. Note that Mayr does not include Earth among the planets—he subscribed to the Tychonic system, in which Earth did not move.
Scheiner also subscribed to the Tychonic system. And it was Scheiner, not Newton, who first proposed a physical explanation for how an Earth-like body could be in an orbit. Livio misses this scientist’s work, too. Scheiner envisioned an orbit being a perpetual falling action, much like Newton, but Scheiner was decades before Newton. Scheiner said his orbit theory would not really help the Copernican system, because heliocentrism had too many other problems. One of those, he said, was the star size issue. But another was the problem of falling bodies: how can objects fall straight down on a rotating sphere? The Earth is not like a cabin on a ship, in which everything moves together, like Galileo said (and Livio relays). On a rotating sphere, things move at different speeds—fastest at the equator, slowest at the poles, etc. Scheiner was right. Things can’t fall straight down on a rotating sphere. Anti-Copernicans envisioned what we now call the “Coriolis Effect”, long before the Coriolis for whom it is named. But they envisioned it as a scientific argument against Earth’s motion—its seeming absence showing Earth’s immobility.
The nuts and bolts of good scientific arguments against Earth’s motion should interest, and be understandable to, a scientist. Translations of Mayr’s and Scheiner’s work exist but are not in Livio’s Bibliography. Anti-Copernican scientific arguments undermine the very title of Livio’s book, as they further drive home the point that Christina, Mayr, Scheiner, and so on were hardly Science Deniers. Still, Livio gives little space to such arguments.
He gives no space at all to the flaws in Galileo’s own scientific arguments. As mentioned above, Livio overlooks Galileo’s statements about the dimensions of stars in several places. But he also misses that Galileo even claimed in the Dialogo to be able to split the telescopic disk of a star with an obstructing marker set up in the distance. That is impossible. The disk-like images of stars that Galileo claimed to see were indeed artifacts of the telescope. Being formed inside the telescope, they could not be split by something outside. A working astronomer, with experience in using telescopes, might have noticed and discussed this bogus claim, something that a historian might not catch, but Livio does not catch it either.
And Livio overlooks something else. Galileo argued that the tides of the oceans were evidence for Earth’s motion. The double motion of Earth rotating about its own axis while revolving about the Sun creates a daily variation in the speed of Earth’s surface which, Galileo said, causes the oceans to slosh back and forth in their basins, creating the tides. Livio refers to both Galileo’s 1616 tides discourse to Cardinal Orsini, and to his 1632 tides discussion in the Dialogo, but Livio misses a key difference in the two. If the daily surface speed variation drives the tides, that should produce a single high and a single low tide each day, with 12 hours between high and low. But Galileo noted that the tides in the Mediterranean Sea have 6 hours between high and low. He said that while the speed variation drives the tides, tidal periods in specific places were influenced by the characteristics of the local ocean basin, as the water surge was reflected back and forth within that basin, thus explaining the 6 hours as being characteristic of the Mediterranean only. And, in the 1616 discourse, Galileo claimed that the Atlantic Ocean tides observed in Lisbon, Portugal showed the full 12-hour period, in agreement with his theory. But in 1619 Galileo was informed (by Richard White of England, who wrote about it) that this claim was in error; tides are 6 hours at Lisbon. Under Galileo’s theory, the Atlantic tides should have a different period from the Mediterranean. Arguably, the Lisbon tides falsified Galileo’s theory; at the very least they strongly challenged it. Yet in 1632 Galileo presented the tides theory again, with one big change from 1616: he omitted mention of Lisbon and the Atlantic tides. In 1632 he put forward his tides theory, the thing he originally intended to be the title feature of the Dialogo, his big argument for Earth’s motion, simply omitting an important but inconvenient fact. It seems facts were not always facts. Despite being a working scientist, Livio misses this.
Christina of Lorraine may not have raised all these specific problems with Galileo, but others who opposed him did. Francesco Ingoli, who played a role in the censoring of Copernicus’s work in 1616, and Melchoir Inchofer, who played a role in the rejection of the Dialogo in 1633, each noted the star size problem in their writings. Zaccaria Pasqualigo, also involved in the actions of 1633, cited the issue of tidal periods.
Galileo and the Science Deniers is therefore wrongly titled. Christina of Lorraine and those like her were not Science Deniers. They chose, from between two theories that fit the new telescopic discoveries (Copernicus’s heliocentrism and Brahe’s geocentrism), the one that fit the Bible—and that fit the known laws of physics. They did not refuse to acknowledge established scientific fact.
Galileo responded to Christina’s challenge by focusing on the Bible. He responded to Castelli’s letter of December 14 with a letter of December 21 back to Castelli, and later with a larger letter to Christina herself. These letters are considered masterful discussions of science and religion, full of words like—
Holy Scripture and nature both equally derive from the divine Word, the former as the dictation of the Holy Spirit, the latter as the most obedient executrix of God’s commands
—and so on. But arguably Galileo’s words said little to a person who accepted the telescopic discoveries as true and was drawn to Tycho’s ideas for scientific reasons as well as religious ones. And those words were about religion. The letter to Castelli became in 1615 the subject of a complaint lodged against Galileo with the Inquisition. And thus “The Galileo Affair”, and its sorry story of religious politics, personality, and pettiness was off and running. Livio’s book is mostly about that, not about science or science denial, despite Livio’s occasional references to modern science denial.
To be clear, the fact that “The Galileo Affair” was about politics, personality, and pettiness, rather than denial of what was seen through a telescope, does not alter the fact that the Church did Galileo wrong. However, I live in the Archdiocese of Louisville, Kentucky, established in 1808 as the Diocese of Bardstown, Kentucky. It was the first inland diocese in the United States, and Kentucky was a slave state. A slave market existed in Louisville, within blocks of the cathedral. Bishops and religious orders and many others in the Catholic Church, officials and non-officials alike, bought in to the corrupt local culture and themselves kept people in slavery. In recent decades there has been much Catholic apologizing for this. Doing people wrong is something human beings and human institutions do: my city; my state; my country; my Church. What makes the Galileo case stand out is that it was supposedly about “science”, and “facts”. Absent someone rejecting scientific discoveries, “The Galileo Affair” falls well behind slavery in the line of Church wrongs—just a case of the Church cruelly bullying a well-connected old guy, who himself bullied opponents like Mayr and Scheiner with the harshest language.
Given that Galileo and the Science Deniers does not provide the sorts of novel perspective and fresh insights (especially as regards the science of the time) that a scientist might offer, and given that “The Galileo Affair” is indeed an overworked arena, why then does this book exist? It provides no ringing endorsement of freedom of thought, or freedom to be wrong. Livio writes that the big lesson from the Galileo Affair is that (p. 200)—
no officialdom, be it religious or governmental, should have the authority to impose punishments on scientific, religious, or any other type of opinions (whether correct or incorrect)…
—which sounds good, but then he adds this:
as long as those neither harm, nor incite others to harm, anybody else.
Since Livio also notes that Pope Urban VIII maintained that Galileo’s ideas were “not only false, but also perilous to humanity [p. 211]”, presumably the bullying of Galileo might be acceptable under the “harm” clause.
No, the book seems to exist to tell a tale of a hero. Consider two items from Galileo and the Science Deniers. One is Livio’s discussion of a copy Galileo made of the December 21 letter to Castelli (the one that was sent to the Inquisition). Livio writes (p. 110):
Probably aware that the letter, which Galileo wrote to Castelli rather hastily, could spell trouble, Galileo produced a slightly revised version, in which he more thoughtfully and cautiously presented the theological issues. He then sent the letter with an explanation to his friend the Florentine monsignor Piero Dini. Galileo asked Dini to show the letter to the Collegio Romano mathematician Christoph Grienberger and, if appropriate, also to Cardinal Bellarmino....
But what Galileo told Dini is that he was sending him a copy of the letter to Castelli “in the correct version as I wrote it”, stating that he suspected that “perhaps whoever transcribed it [the copy sent to the Inquisition] may have inadvertently changed some word”. Galileo presented the “revised” version to Dini as being the original version. Indeed, historians have long been in the dark as to what really was the original version. Only in 2018 was Galileo’s subterfuge discovered, when the original letter in his own hand, with his marks for the revision for Dini, was found mis-filed in a library. There was no transcription error in the version sent to the Inquisition. Thus in Livio’s tale a lie told to a friend to release a milder version of the letter becomes a revision sent to the friend with explanation.
The second item is Livio’s willingness to portray Galileo’s opponents in really poor terms. Simon Mayr’s understanding of Jupiter’s moons is not in Galileo and the Science Deniers, but Galileo’s labelling him a “poisonous reptile” and “an enemy not only of me, but of the entire human race” is (p. 69). Livio invokes “horrifying memories of totalitarian regimes past and present” in regards to the Inquisition (p. 191), and writes that
Cases such as those of self-exiled dissident Saudi Arabian journalist Jamal Khashoggi and Russian defector Alexander Litvinenko, both murdered by their native countries’ governments, immediately come to mind.
Galileo’s opponents are poisonous reptiles indeed.
Granted all this, and granted the book’s lack of interest in the scientific debate of the time, Galileo and the Science Deniers simply retells a tale about a hero. Livio does that well. He does not overlook the hero’s personality flaws; the book is not a hagiography. But he does overlook the hero’s scientific errors. The hero who omitted crucial facts in presenting his tides theory is logical and brilliant. His opponents’ interest in and acceptance of science is overlooked. Thus, there is the hero and his friends, and there are the bad guys—enemies so bad that the murder of Jamal Khashoggi comes to mind.
That is a shame, because science today does not need another version of this tale. Livio is right about the problem that science denial poses to science; his point there is important and right on the target. But science denial always involves tales of conspiracies on the part of big bad institutions to cover up the truth revealed by the lone hero, or the scrappy rag-tag band of heroes. As Bob Garfield of NPR’s “On the Media” very recently put it, “a victim, someone who has been silenced by ‘The Man’, a martyr to truth-telling... is a recurring theme in the conspiracy genre”. I have said many times on this blog, if we want to strike a blow against science denial, we need to stop retelling the hero tale—clearly the previous 40,000 retellings have not done any good. We need instead to tell how science really worked during the debate over Earth’s motion, and still works now, and how complex, dynamic, and interesting that debate was. We need to give Christina of Lorraine her due. We will not combat science denial and its associated conspiracy theories by telling people, contrary to the historical record, tales of how the very birth of modern science was marked by rejection of facts and a big conspiracy to hide The Truth. We will combat science denial by showing how vigorous scientific debate over a universally accepted set of facts was present at the very birth of modern science, as it often is in science today. Galileo and the Science Deniers does not do this, despite its author being a scientist. It retells a tale that is central to the genre of conspiracy and science denial, and so it will in all likelihood contribute the very science denial problem it purports to help solve.