Hello, and welcome to Western SIV, episode two hundred and seventy one,
Galileo, Part three. Quote. When Galileo caused balls, the weights of
which he had himself previously determined to roll down an inclined plane, a light
broke upon all the students of nature. They learn that reason has insight into
only that which it produces after a plan of its own, and that it
must not allow itself to be kept, as it were, in nature's leading
strings, but must itself show the way. End quote Emmanuel Kant, Critique
of Pure Reason, seventeen eighty one. The question, of course, is
was Galileo an experimental scientist? To a large extent, I suppose that's been
the question I've continuously posed throughout this series. Few subjects in the history of
science are more contested. Even today. There are a number of possible sources
of confusion here. First, of course, what is an experiment? In
modern usage? The idea of an experiment involves the reproduction of some naturally occurring
phenomenon in a carefully controlled and therefore artificial setting what Kant called reason proceeding quote
after a plan of its own end quote. We might distinguish between an experiment
which is designed to play a part within an argument, perhaps even to test
a hypothesis, and an experience. An experience is different. I personally have
experienced thunder a lot, but I don't have any idea how to create an
experiment that would establish the cause of thunder. Now, the other part of
this is observation, because observation tends to be the phrase that gets used the
most, especially amongst early modern astronomers. Observation can be placed somewhere between experience
and experiment. Having observed, for example, that I see lightning before I
hear thunder, and having hypothesized that they both have the same cause, I
would actually be a good step of the way toward devising an experiment that would
make it possible to compare the speed of sound with the speed of light.
Now, of course, in order to avoid unnecessary complications, this is a
very loose determination of the word experiment, or at least the concept of experiment.
Galileo had experiments, and I've called them experiments, and frankly, it
would probably be more accurate oftentimes to speak of these as observations. For example,
Galileo's trajectile experiment, you know, is really more of a observation.
He probably just recognized that it formed a parabola based off what he was watching.
He didn't attempt a series of controlled observations. He didn't study what would
happen if he changed the speed dramatically of the projectile. In other words,
he didn't really tinker with any of the variables. Now, the distinction between
an observation and an experiment might be something that means refinement even in our modern
world. But everyone knows, i think, collectively, what an observation is
and generally how you do it. But such was not the case in Galileo's
world. Cicero's Latin had no word for either experience or experiment. Experimentum enters
Latin around the year sixteen hundred, but even Galileo rarely uses the term when
writing. He in fact, only uses the Latin for experiment twice, and
only once does he use the term in Italian. Galileo indeed assume that there
were only two types of knowledge, knowledge based on proof like mechanics, and
knowledge based on experience. He did, however, have a term for testing
a hypothesis In Latin. This is called periculum fosserae, which means literally to
put to the test. This is not necessarily the same thing as our modern
term hypothesis. It wasn't an open ended test. Instead, the idea was
more like having a range of possibilities you considered in advance, and then the
experiment ticked off the boxes yes or no. So really it's very much a
binary operation. It's either a zero or a one depending on what happens.
Thus, it's not clear yet if it should be too soon to say that
Galileo was an experimental scientist. It may be frankly anachronistic at best. Certainly
he used experiments or things that look like experiments, but he was never an
experimental scientist in our modern sense of the world. Not that that diminishes his
value to the development of experimental science in any way. A classical example of
our tendency to overestimate the value of our own knowledge is in a passage of
the Two Ciances by Galileo. Here he tells us to fill a glass container
with wine and seal it with a stopper containing a very small hole. The
hole needs to be so small that there will be no flow of wine out
of the container if we hold it upside down. Now, place this container
upside down in a basin of water. Slowly, very slowly, the wine
will drift out of the bottom of the container and fall to the bottom of
the basin, while the water will seat it up into the container. Essentially,
the water and the wine will switch spots. The great historian Andrea Corey
read this passage and thought it was ridiculous. Everyone knows that you can dilute
wine with water, so he reasoned that in this case you would both end
up with a basin and a container full of diluted wine. Thus, he
concluded that what he was reading and Galileo was actually a thought experiment. Galileo
could never have tried it out in practice. Corey's conclusion is remarkable, as
he could hardly have imagined that Galileo did not know that you could dilute wine
with water. But no one actually repeated this experiment until nineteen seventy three,
and when they did, it turned out that Galleo was right and Corey was
wrong. So there's an important general conclusion here that we can draw from this,
and that is there's no way of testing whether Galileo was an experimental scientist
other than by trying to replicate the experiments he describes. It used to be
thought that he had laid claim to a significant number of experiments that he had
never actually conducted. Yet there really appears to be in all of his writings
only one example of his representing a guestimate as if it were an actual experiment.
Hence, in the end, even if Galileo did not follow all the
tenets of experimental science as we call it today, there is no doubt,
at least in my mind, that Galileo effectively invented the modern idea of experimental
science, and the importance of that invention simply cannot be overstated. One of
the most important pieces of evidence we have relating Galileo and experimental science is a
letter from sixteen oh one in which he details a classic experiment designed to prove
the isochronicity of the pendulum. In order to understand this experiment is necessary for
us to take a quick step backward. In on Motion, Galileo describes experiments
involving bodies rolling down in kline slopes, Yet also in his textbooks on mechanics,
compared the force required to pull an object up an inclined slope a perfectly
smooth object, in this case over a perfectly smooth slope, with the force
required to just lift it vertically straight up. It was easy to see that
an incine slope was simply a way of slowing down the acceleration of a falling
object. It could be hypothesized at the speed at the bottom of the incline
slope, assuming no friction, would be the same as the speed that the
object would reach if it had fallen from the same height, and that the
time it would take to descend the slope would be in the same ratio to
the time of the fall as the length of the slope to the height of
the fall. If one could devise an exact enough way of measuring time,
one could confirm this hypothesis by rolling balls down polished surfaces. Galileo, of
course, didn't know that rolling balls behave slightly differently to sliding objects because they're
rotating at some point. Galileo carried out experiments to confirm this result, but
he will have been con fit of it long before he tested it. He
knew the results could never be perfect, of course, the ball would never
be perfectly round, the slope never be perfectly polished, but all in all,
the results were entirely satisfactory. Galleo then asked himself a follow up question.
Suppose an object takes one unit of time to fall an arm's length,
is there a formula for calculating the length and steepness of all the possible slopes
that an object would slide down in the same unit of time. Clearly,
the longer the slope, the steeper it had to be, until a slope
of eighty nine degrees is going to be nearly an arm's length. The shorter
the slope, the nearer it must approach the horizontal, until a slope of
one degree will have almost no length at all. Galileo probably doodled around with
lengths and slopes until you realized that if all the slopes ended at the same
point, then all the starting points would form a curve. What sort of
a curve? The simplest curve is a circle, And Galileo was soon able
to demonstrate, on the basis of his earlier hypothesis that if a circle were
placed either vertically, then an object sliding down any part of it to the
lowest point would take the same time as an object sliding on the other side.
There was no need to test this. It was simply had to be
true if the initial assumption was true, and any test of the initial assumption
would confirm this. Essentially, what Galileo is doing here is constructing a science
of falling bodies, which functions like mechanics. It was idealized, abstract,
and of course concluded only imaginary bodies. But it was of course deductively true
given an initial hypothesis and definition. But what about the pendulum. Surely all
pendulums of the same length would take the same time to swing through different arcs,
whether wide or narrow. Galileo could see that this should be true,
But try as he might, he could not find a geometrical method of proving
it. He had no mathematical procedure for handling a constantly changing angle of dissent.
Indeed, he was bluntly stuck. But this is when he stumbled upon
a new author named Gilbert, and Gilbert was all about experiments. In fact,
he had shown that you could prove theories through experiments. Could Galileo show
through an experiment that all pendulums of the same length will swing through differing arcs
at the same time? Could he prove this new law in fact, if
he couldn't in theory. It is precisely this experiment that Galleo describes in the
first of his letters. After he read Gilbert, he wrote to a friend
in Fact, describing pendulum experiments with which he claims he was able to demonstrate
this law. Now, these experiments for historians have always been difficult, because
we know that Galileo's hypothesis is false. The length of the pendulum has to
be made to alter very slightly as it swings if every swing, whether wide
or narrow, is to take the same time. Galileo says that a pendulum
swinging through a large arc and a pendulum swinging through a small arc will swing
together, never getting the swing out of step with the length of the pendulum.
Galleo describes the differences of arc that he has in mind. Modern theory
suggests that these two pendulums would be an entire swing out of step after only
thirty or more swings. The conclusion, therefore is either Galileo never actually conducted
the experiment that he describes in these letters, or he simply made up the
results, or maybe there's a third option. The third option is that if
you do perform this experiment incorrectly, you do get the result that Galileo describes,
because what happens is that Galileo was trying to allow for air resistance,
and therefore he changed the calculations in order to make it look like the pandulums
had swung at the same time. In other words, what he's doing is
his account trying to account at least for variable air resistance without being able to
do so, and to an extent, I suppose falsified the results, although
it was a falsification based on assumption that he certainly believed. So what all
of these experiments lead Galileo two is a final conclusion that gives an explanation of
a path followed by a projectile. In other words, he's finally able to
explain what he observed in fifteen ninety two. And really what this is is
the culmination of hundreds of different experiments and observations that finally allow him to prove
that a cannon would shoot furthest if it's set at an elevation of forty five
degrees, and he could use his pendulum now to measure time more accurately than
ever before. What he wanted to do, of course, was get these
results into print. They would establish a new science. They would encourage others
to adopt the experimental method. They would prove finally Galileo was a worthy successor
to Archimedes, and they would show Copernicanism was one hundred percent compatible with the
laws of physics. In sixteen oh four, Galileo was forty years old.
It had served a long apprenticeship. It was beginning, at long last to
make some headway against his financial burdens. He was about to become famous.
He began writing in Latin, of course, the book that he knew would
have an impact far greater than anything else. The evidence suggests indeed, by
sixteen oh eight he had come really close to finishing this book that we can
find its text produced in Latin, within its Italian dialogue on the two sciences.
But one thing that's really interesting about all of this is that if Galileo
was an experimental scientist, that is not how he wanted to present himself to
the world. He wanted Europe to look on him as another Archimedes, the
ultimate deductive scientist. The true role of experiment, in Galilee's mind was not
to explain the true role of experiment was to establish facts that deductive reasoning could
then explain. Galileo's experiments were preparatory procedures undertaken in his quest for proofs.
In fact, part of the reason Galileo fastidiously avoided using the term experiment was
his desire to avoid being labeled an experimental scientist. It did not work.
To one contemporary Galileo was quote the founder of the experimental method in all its
exactness end quote. After his death, Galileo's students founded the Academia del Cimento,
dedicated to the pursuit of scientific knowledge through experiment and experimentation. Frankly,
a Galileo published his book on Projectiles and Falling Bodies and done nothing else.
He would have been a significant figure in the history of science, the founder
of modern physics, the greatest physicist before Newton. In later years, Galleo's
friends urged him repeatedly to publish, but he didn't do so until sixteen thirty
eight. This is a thirty year delay that cries out for an explanation.
I mean Galleo had endless opportunities to publish. He could have published at any
time after sixteen sixteen. Banned from defending Copernicanism. This would have been the
sensible thing to do. He even had a clean copy of a draft prepared
in sixteen eighteen so that he could resume work. And for this delay,
there's really only one explanation that works, and that is in Galileo's mind,
this project was inseparable from the much larger and in his mind more important one,
the campaign to vindicate Copernicus. Prestige and fame weren't enough for Galleo.
Proving ours thought all wrong wasn't enough for Galleo. Revolutionizing physics is not enough
for Galileo. There was something else that mattered. But what exactly was that
something? And this is I think, really the question, because it defines
what Galileo was all about. And in Galileo's view, the answer to this
question is obvious. He wrote as follows. Quote. The constitution of the
universe, I that is, Galileo believe, may be set in first place
among all natural things that can be known, for coming before all others in
grandeur by reason of its universal context. It must stand above them all in
nobility, as their rule and standard. End quote. No other thing stood
above the universe in Galileo's mind, everything depended upon it, and in his
mind Copernicus had it right. But how to prove it well? The answer,
it turns out, as we'll turn to now, is you have to
change how you see. In autumn of six oh four, a new star
appeared in the sky. News of it spread rapidly amongst those interested in astronomy.
Thirty years earlier, in fifteen seventy two, ticobrahe had turned a new
star into quite the celebration throughout Europe. Now, of course, the problem
is is, according to Aristotelian philosopher, the heavens were unchanging, eternal,
perfect. There could be no change in the heavens, and any change that
did take place had to occur in the vicinity of Earth. In their view.
Consequently, the choice was simple. Either that new star wasn't new at
all, it had always been there, or it wasn't a star at all,
but some peculiar phenomenon in the atmosphere. Since Tico's new star soon disappeared,
the argument was left unfinished, to be immediately reawakened by the appearance of
this nova in sixteen oh four. As a Copernicus Galileo, of course,
knew where he stood. If Copernicus was right, the distinction between a sublunary
and superluinary world was misconceived. There was no distinction between Earth and the heavens.
The Earth was in the heavens and inseparable from them. If there was
some change on Earth, then equally there could be change in the heavens.
As someone who taught the military sciences, Galileo also knew how to measure distances.
He knew it was not necessary to approach an object to work out how
far away it was, so long as there was some other point of reference
whose distance was known. By looking at an object from different positions, you
could see how its relationship to other objects altered. Simple geometry could turn a
measurement of a parallax into a calculation of distance. If the new star,
when looked at from different places on the Earth's surface, had an unchanging relationship
to the star around it, then it was very far away, clearly much
further away than the moon. Galileo had soon collected the information to prove that
the new star was indeed a star, that it was certainly not closer to
the Earth than the moon. He gave a series of public lectures on the
new Star, attracting large audiences and provoking vigorous debate. Galileo must have considered
publishing a version of his lectures on the nova. Certainly, given the mood
in Europe at the time, they would have sold well and would have constituted
his first proper scientific publication. In the autumn of sixteen oh four, Galileo
could show that the new star's location appeared to be the same when viewed from
different European cities. The star then disappeared below the horizon of the night sky,
to reappear in the spring of sixteen oh five. It was clearly Galileo's
hope that when it reappeared, its relative position would have changed. If Copernicus
was correct, he would now be looking at it from a point distance from
his previous point of operation by the diameter of the Earth's orbit. Galileo must
have waited with anxious anticipation for the star's re appearance, but there was no
change in its location, and while this was a disappointment, it wouldn't have
been much of a surprise given Galileo's understandings. Be that as it may.
Galileo's letter made it clear this was a star. This was something in the
heavens, and it was new. And it turned out Galileo had some i'll
put it in air quotes support. You see. In addition to Galileo's letter
slash pamphlet, a second pamphlet appeared defending Galleo's interpretation of the New Star.
It was printed in Florence in sixteen oh six, and it was written by
ali Berto Mari. But it was a ruse. Mari was Galileo. He
had written under a pseudonym. Now, interestingly, in this pamphlet, MARII,
that is, Galileo never explicitly discusses Copernicism, indicating maybe he knew he
wasn't supposed to. But he does refer to Copernakiss a few times, always
with approval. So after just some heated arguments and good natured mockery of the
Ristotelian establishment, Galileo's first involvement in astronomy came to an end, and he
turned his attention back to physics. Early in sixteen oh eight, however,
a Dutch spectacle maker discovered that if a convex lens was held behind a concave
lens, you could enlarge the image. He mounted the lenses in a tube
with a sliding mechanism, thereby making the first telescope. Soon a number of
different people were claiming to be the inventor, and word of the discovery spread
rapidly. In May of sixteen oh nine, Galileo claimed to have quote unquote
reinvented the telescope. Would that really means in this instance is that he made
a telescope without ever really seeing one, and without having been given an account
of how one was constructed. He would later claim that reinventing was just as
difficult as inventing. Archimedes, after all, had invented weapons of war that
no one had been able to reinvent. Galileo would also claim that his knowledge
of optics was crucial for being able to reinvent and improve the telescope. Galileo
certainly had some knowledge of optics, but it is not clear that this played
a significant role in either the reinvention or the improvement of the telescope. All
that was involved was intelligent trial and error, in other words, experimentation.
Galileo saw at once that the number of possible lens combinations was limited, and
so all he had to do now was try them out. Galleo's first telescope,
using lenses made for spectacles, magnified only three times. The best Dutch
telescopes of the day magnified double that, about six times. The lens quality
definitely was poor. There would have been a halo consisting of the colors of
the rainbow around the edges of every object, and the image would have been
blurred because the curvature of the lens was irregular, its value limited. Galileo's
true genius, though, was that he grasped at once that the telescope could
be improved. Now today, we live in a world where manufacturers are constantly
offering us improved version of products. So if you or I had been shown
a primitive telescope, we would have asked immediately how it could be improved.
Galleo's world wasn't like this, though. Even new technologies guns, printing presses,
compasses were improved slowly and over very long periods of time. By the
summer of sixteen oh nine, there were thousands of people mathematician, scientists,
engineers who had seen and used the new telescopes, but Galileo was the only
person, the only one who immediately saw the challenge how could it be improved.
Everything that he had done throughout his life had prepared Galileo for this moment.
Galileos soon that a telescope that magnified eight times. He took this to
Venice, where he displayed it to the city's rulers. It may have been
the first telescope many of them had seen, though some will have known that
others were offering to sell the secret of how to make one. Standing on
the top of the bell tower in Saint Mark's Square, they looked out to
the sea and saw ships through Galileo's telescope that were invisible to the naked eye.
The technology had obvious military potential. Galleo assured them that additionally, equally
good telescopes could be made, supported by powerful friends and associates. He pressed
his claim for reward, and it was agreed that he should receive an appointment
at the university for life and a salary of one thousand ducats a year.
In return, he agreed to spend the rest of his life in the service
of the Venetian state. Now impartial bystanders soon started muttering the Galileo had practiced
nothing but deception. Telescope vendors were spreading out across Europe carrying packs full of
Dutch made telescopes. Soon one good bye a telescope quite cheaply in Saint Mark
Square, right where Galileo had demonstrated this new invention. Now, this,
of course is the first ambiguity, and we don't know the answer to this.
But had Galileo presented himself as the inventor of the telescope or merely as
an improver of the telescope? And of course that leads to another question.
If Galileo's telescopes were better than the other telescopes that were now generally available,
was there a secret to their construction? Or could anyone who put in a
little time and trouble produced an improved telescope. The Venetian establishment seems to have
had its doubts. They couldn't go back on their word unless they were prepared
to charge Galleo with a crime. But by the time the Venetian Senate came
to vote on his reward, it seems clear they felt like they had been
misled. Galileo's new appointment and his new salary was now only set to begin
when his existing appointment came to an end, and the Senate decreed that his
new salary was never to be increased. We could guess that Galleo was offended
by this restriction, seeing it as an invitation to seek patronage elsewhere. The
new salary was, after all, no better than one of his friends,
who went on to double his salary in the years that followed. Although he
didn't receive an appointment for life in sixteen oh nine, both Galleo and the
rulers of Venice were trying to make sense of this new technology. Galileo was
certainly in a position to guess that others would soon be able to produce telescopes
as good as his. But it's also the case that Galileo had kept a
lead in the production for the moment of high power telescopes. By the autumn
of sixteen oh nine, he had a telescope that magnified twenty times. Four
years later, by the beginning of sixteen thirteen, one that magnified thirty times,
and he was still well ahead of the competition. In fact, Galileo
managed to stay ahead for twenty years. Galileo really did have something to offer
Venice, but his telescope was not a new invention, nor was it made
with any special techniques. I don't think that there was any deception here when
dealing with the Venetian government. Rather, what the Venetian government failed to comprehend
was that when they were buying this new technology, they were buying the man
who was committed to improving it. But again, that just wasn't the mindset
of people in early modern Europe, so it's hard to fault them for it.
Now. Interestingly, this is just kind of an aside, But around
the same time we get some correspondence between Galileo and his younger brother. It
seems that Galileo sent him a few telescopes so that he could give them to
influential people and spread word of Galleo's discoveries. His brother sold the telescopes instead
and kept the money. He wrote to Galleo a bit later asking for more
telescopes to sell. Galleo didn't send any. The whole affair is an interesting
reminder of the reality that the great men and women in the past didn't live
in a bubble. They had annoying familial relations too. In Venice, in
June and July, there's about sixteen hours of daylight and only eight in December
and January. In the autumn of sixteen oh nine, as the days shortened,
Galleo turned his improved telescope toward the heavens. He mounted it on some
sort of stand, But still he had to learn how to slow his breathing.
Even his pulse seemed to shape the telescope, and as the evening temperature
dropped, the glasses kept missing up. In early January sixteen ten, he
discovered he could reduce the halo round objects by fitting a circle of masking material
with an oval hole on the end of it over the lens. In photographic
terms, he stopped the lens down. Still, the stars remained mere points
in the heavens, except that there were many more of them. Now he
discovered that the Milky Way was not a mysterious white band in the sky,
but a vast number of small stars, individually invisible to the naked eye.
Elsewhere there were new stars to be seen. It's easy for the significance of
these new stars to escape a modern reader. It might be thought, it
hardly matters how many stars there are. But Galileo's contemporaries believed that the universe
embodied a rational purpose the Sun, the Moon, and the stars existed for
one purpose, and one purpose only, to give light to the Earth.
Invisible stars were a weird new concept. What purpose could a star serve if
no one could see it? Only a few Copernicans had imagined a universe so
large that there were distant stars invisible from Earth. As for the planets,
through Galileo's telescope, they were not points, but tiny discs floating in space.
Naturally. Galileo turned his telescope to the Moon, which was so greatly
magnified that he could look at it less than half the time even with his
twenty power telescope. Everyone knew that the Moon wasn't perfectly uniform in a pearance,
but the philosophers still insisted that it had to be a perfect sphere,
even if parts of its surface were more reflective than others. If the Moon
were smooth, the line between the illuminated half and unilluminated half should be perfectly
irregular. But Galileo, looking through his telescope, could see that the line
wasn't regular. Moreover, near the margin between the illuminated and ulluminated half,
he saw two anomalies on the unilluminated side of the margin, he could see
little flecks of light. The sun was clearly reaching some areas before it reached
others. These must be high points. On the illuminated side, he could
see dark spots which the illumination took longer to reach. These must be shadows.
Galileo's interest in painting and his experience looking at paintings where the tricks of
light were used to convey textures and shapes, probably helped him understand what he
was seeing. But he also grasped at once that what he was seeing was
comparable to a familiar phenomenon on Earth. At dusk and dawn, the sun
stays on the mountaintops when the valleys below are deep in shadow. Galileo therefore
had discovered that the Moon had a landscape, a landscape of mountains and valleys.
In this respect, it was just like the Earth, and this was
corroboration of his view that the Earth seen from the Moon would look just like
an enormous moon. But there was so much more. On January seventh,
Galileo turned his telescope to Jupiter and noticed three stars arranged in a line,
with the planet toe to the east, one to the west. He had
assumed that these were yet more fixed stars, But the next day, when
he looked again, now all three stars were to the west of Jupiter.
Although Jupiter itself was moving from east to west, somehow, to fixed stars
had overtaken Jupiter. Galileo now began to observe Jupiter every night. By the
eleventh of January, he had decided that he was observing three satellites orbiting Jupiter.
On the thirteenth he discovered a fourth. Galileo now knew he had made
a truly momentous discovery. By January the thirtieth, he was in Venice arranging
for the publication of a book on his telescopic discoveries, the mountains on the
Moon, the nature of the Milky Way, the moons of Jupiter, all
the while continuing his observations. Galileo was in a hurry. He knew other
people had telescopes, and even if theres weren't as good as his, it
probably wouldn't be long until someone else had a telescope capable of looking at Jupiter's
moons, and so Galileo, now aged forty six, was writing a book.
As he worked, he consistently tinkered with the title suggesting he believed the
book was designed to become a work of great importance. It was common when
printing a book to print the body of the book first, and then to
add the prefatory matter. It's clear that this happened in the case of Galileo's
observations. The large title on the first page to be printed was Astronomous Nunicus,
which translates to the astronomical message or astronomical Messenger. In his correspondence,
Galileo referred to the book in Italian as avisio stronimko or astronomical news, or
maybe even starry news. But the fine old title, which was finished only
as the last pages went to press on March the twelfth, was Siderius nuncus,
or as we know the title today, the Starry Messenger, a Messenger
from the stars. The book proved to be a collection of observations, or
more like a report than a narrative work. Galileo despised books about books.
Prior to him, that was kind of all you really ever got out of
scientists. Galileo went out of his way in writing his book to prove it
was different. Indeed, after its publication, every other book on the stars
became irrelevant, at least according to Galileo. Galleo doesn't offer facts in The
Starry Messenger. He offers us observations. Some require no interpretation at all,
others just a little deductive reasoning. Shadows on the Moon become craters with a
little thought. For example, some of the illustrations of the moon within the
book book are amazingly accurate. They did have one significant flaw, however,
which is puzzled later scholars. A singular feature, a crater, which Galleo
describes as being as large as Bohemia. It appears in large effects, so
big that critics have complained that if the illustrations were accurate, it would be
visible to the naked eye. Now, the simple answer as to why this
appears is that Galleo was persuaded that this singular feature was far larger and more
noticeable than any other because he had already seen it with his naked eye.
In the end, what's happening here in The Starry Messenger is Galileo is embellishing
something because he believes so firmly that he is seeing it or has seen it
with the naked eye. Did he probably not, But it doesn't change the
fact that as a crater it's large. Now. Interestingly, after the Starry
Messenger, Galleo did not include any illustrations in his books, and the reason
is quite obvious. He expected readers to have or to obtain telescopes of their
own. It was as though he was saying to all of Europe, the
answers are there, go and see for yourselves. But then, on the
twelfth of February, Galleo received a letter from Belisario Vinta, the secretary to
the Grand Duke of Florence. He reported that the Grand Duke was quote unquote
stupefied by news of Galileo's discoveries. Galileo replied the very next day with the
Grand Duke, who was called Cosimo, he has succeeded his father here before,
like some of these new satellites to be named the Cosmic stars after him?
Or would he prefer them to be named the Medician stars, given that
they were four of them and he had three brothers. Quickly the answer came
back. It was written on the twenty of the February and would have reached
Galileo a few days later. Cosmic, they wrote, was too ambiguous it
would not automatically make people think of Cosimo Medician was better. Galileo made his
arrangements for publication at the end of January. He had an effect booked time
on the press and could not wait for a reply. When Vinta's letter relaying
the Grand Duke's choice arrived, the word cosmica was replaced with Medica. It
would have been shortly after this that Galileo chose the final title for the book
and wrote a prefatory letter in praise of Cosimo de Medici. There's another more
significant discovery to be made from examining the surviving manuscript. There are three passages
in this book in which Galileo unequivocally declares his support for Copernicanism. Now it's
clear that when Galileo received Vinta's letter on the twelfth of February, he had
virtually completed a draft manuscript which contained not a single reference to Copernicanism. The
first and third sections of the book open with references to Venus and Mars orbiting
the sun, but a knowledgeable contemporary would have been more likely to interpret this
as a reference to Tico Brahe, not Copernicus. In mid February. Therefore,
Galileo made two bold and consequential decisions. He decided to put a reference
to sideda Cosmiica in the title of his book and into its conclusion. And
he decided to commit himself explicitly to a Copernican argument and to include within his
book an implicit attack on Tico Brahe. Galileo explains then that the phenomenon of
earth shine and shows that the Earth lights the Moon just as the Moon lights
the Earth. As Galileo says, earth shine is powerful evidence in favor of
the Copernican claim that there's no difference between the Earth and the other heavenly bodies.
Of the discovery is reported in The Starry Messenger. This is one of
two which tell against the cosmology of Ticobrahe. The implications of the other,
the discovery that planets can have moons so that the Earth principle could be a
planet, were only put in the final pages. It's easy to see what
changed, or at least what Galileo hoped was about to change. When Galileo
entered into the contract with his princer, he was just an insignificant professor,
But after the twelfth of February, he became convinced that he was about to
receive the support of the powerful Medici family, and therefore he was ready to
come out in support of Copernicanism. It's worth pausing to see what Galileo was
doing in mid February. He was on the threshold of publishing a book that
would stupefy the scholarly world. Success was assured this was definitely going to sell,
and so he decided to raise the stakes and make a success uncertain.
He committed himself to dedicating the book to Cosimo Dimnici before he even had permission
to do so. Even more boldly, he decided to maximize the opposition to
his book and minimize support for it by not making it simply anti Ptolemaic but
explicitly Copernican. Of course, since he believed in Copernicanism, this had the
advantage of allowing him to speak his mind, but it was a rash move
to the extreme. Interestingly enough, if you look at the book, the
rhetorical high point occurs in almost the exact middle, and it's remarkable in about
three respects. It's transparently Copernican. It announces Galileo's great project, the system
of the world, and it's only one of two places where Galleo ever uses
the word experiment in Latin. Some of these passages lay out Galleo's thoughts on
these new discoveries, and with these words he both announces an imminent intellectual revolution
and provides a sketch of his much larger work, Dialogue, which would not
be published until sixteen thirty two. Here's the relevant passage quote, Let these
few things said hear about this matter suffice we will say more in our system
of the world, where with very many arguments and experiments, a very strong
reflection of solar light from the Earth is demonstrated to those who claim that the
Earth is to be excluded from the dance of the stars, especially because she
is devoid of motion and light. For we will demonstrate that she is movable,
and that she surpasses the moon in its brightness, and that she is
not the dump heap of filth and dregs of the universe. And we will
confirm this with innumerable arguments from nature. End quote. The story Messenger was
published on the thirteenth of March. Within a week, five hundred and fifty
copies were gone. Galileo, who was supposed to get thirty free copies of
the book received on these six. Because it's sold so quickly, there is
no doubt that fame for Galileo had arrived at last. But at what cost.