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for most of recorded history, mankind, including its astronomers, held that the Earth was the motionless center of the universe that was expressed in a formal way by Aristotle about five centuries before the common era, or the birth of Christ. And the theory was formulated more exactly by Ptolemy about 150 years before Christ or before the common era.

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And it was challenged only in medieval and Renaissance times, principally by Copernicus in the 15th century and later by Galileo. Galileo was a very interesting person because he attempted to demonstrate Copernicus his view that the sun was the center of the universe, or to express the theory more exactly that the Earth moved contrary to the Ptolemaic position.

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But there was another person in the wing, so to speak, who was a near contemporary of Galileo named to Cobra, a Danish astronomer who, shortly before Galileo did his work, came to a different kind of conclusion. He held that while the Earth did not move nonetheless, the planets revolved around the sun.

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While it's all very complicated, there being two major schools, Geo centric school which held that the earth was the center of things and Helio centric school, which held that the sun was the center of things. We'll try to work out the complex factors here, but the better way to do it is not by my talking about it.

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The better way to do it is to talk with Galileo and Tycho Brahe themselves, and we'll meet them when I return in a moment. Mhm, mhm conversation from the University of Florida and exchange of ideas in the fields of history, literature, science, religion and public affairs.

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Your host is Michael Gannon, professor of history and associate dean of the College of Liberal Arts and Sciences. My guests on this conversation are Galileo Galilee, Florentine philosopher, physicist and astronomer. I thank you very much, Galileo, for going to considerable trouble to be on conversation, and my other guest is, as I say, Tico Tico, you are a Danish astronomer noted for the accuracy of your measurements before the time of the telescope.

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I thank you very much also for coming on conversation. Thank you, Mike, considering the the alternative, it's most pleasant to be here. May I ask you a few biographical data because with all due respect, were not as familiar with you by name, as we are with Galileo.

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Your name is Tico bra, and that's Danish. That's correct. Technically, my Danish name would be Tig. But as common with my contemporaries have legitimized the form to Tico. And you embarked upon a career at the University of Copenhagen, teaching mathematics and astronomy and so on. And you interested yourself in the measurement of the heavenly bodies.

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Why and how well, I became very interested. Early on, I saw an alignment of Jupiter and Saturn. It's called a conjunction, and what interested me was that the current tables available those of, uh, so called Alfonsin tables. And those called the Plutonic tables, which were based on the work of Copernicus, were woefully inadequate.

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In fact, the Plutonic tables were several days off in predicting this alignment, so that spurred my interest to set about observing the planetary motions in in an attempt to correct them. Accuracy, I think, is critical to good science, and you constructed devices that helped you in the measurements.

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They were not telescopes as yet. What were the these devices? That's correct. Traditionally, in astronomy, we used handheld quadrants, quarter circles or sexton, 60 degree likes and I had the very best craftsman available. Create in particular a large wall mural, which was a quadrant, some 7 ft radius.

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And they were very carefully graduated. So I was able to make observations for planets down to about four minutes of arc, which is, uh, infinitely better than that of Ptolemy or any medieval or ancient thinker. Um, for various stars, it was even better, perhaps down to two minutes of accuracy, so very proud of the quality of my instruments and hence by observations as well.

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Now, as regards the great controversy between the followers of Ptolemy and the followers of Copernicus, you seem to have devised third mhm theory or opinion which held not that the sun and planets revolve about a motionless Earth, but that the planets revolve around the sun. And that conglomeration, if I could call it that, revolves around a stationary earth.

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That's correct. Well, now, before I get back to your theory, I want to know from Galileo. Why could you not by that as an acceptable compromise? Well, for several reasons you see, I did have an advantage that Tico did not have. I had the telescope which I learned not by my own devising, but from the Dutch.

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Now, that was a little bit later, of course. And I had the advantage of being able to observe the heavens with the help of this object which made things seem a lot clearer. And so that perhaps might have been one of the reasons why I came to accept the Copernican theory.

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I hasten to point out that I had not always been a Copernican. I was schooled in Ptolemy. I knew Ptolemy very well taught Ptolemy at the University of Pisa and at the University of Padua and only slowly came to become a Copernican. So it wasn't an easy road.

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But I did have the telescope that was an advantage. Justify May. Did you see anything with the telescope Senior Galilee that I didn't see with my naked eye instruments? Well, I did detect there were moons of Jupiter and I don't believe that anyone prior to my observing these new satellites that would revolve around a central body prior to my time these new ones.

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I don't think that you were aware of those nor do I know of any other individual who knew that Jupiter also had moons in addition to our earth. And that proves what precisely? Well, well, it doesn't prove that Copernicus was correct. I concede that I didn't notice, of course, that the moon was very different from what Aristotle had taught.

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Aristotle, as you may know, taught that the moon was perfectly smooth. With my telescope, I was able to detect that there were mountains and craters on the moon, just like there are in the Earth. And to me, that undermined the veracity of the Aristotelian Ptolemaic system and consequently cast doubt in my mind as to the acceptability of these ideas.

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You also discover the phases of Venus, did you not? Yes, That was a little bit later I wrote a book in 16 10 called The Starry Messenger, in which I laid out for all to see these observations that I had made with the telescope. But in that book, I did not mention that the fact that Venus has phases, it's interesting that you bring that up because the phases of Venus is a phenomenon that cannot occur in the Ptolemaic system.

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And when I was able to detect that with my telescope, you see well, then I knew that Ptolemy had some major adjusting to do, in fact so major that he would not be able to withstand such criticism. And that, as I suggest, was one of the reasons why I came to accept the doctrine of Copernicus.

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Okay. The doctrine of Copernicus then holds that the sun is stationary and that the planets and earth revolve around the sun and the earth. And the other planets that were well known Mercury, Venus, Jupiter, Mars, Jupiter, Saturn. But they all go around the sun as the central body.

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Yes, that's true. Tico you allow with Copernicus that the planets go around the sun. Why not the Earth to? Well, um, there are several good reasons, Not least common sense. Um, it doesn't seem to me that the Earth moves. One certainly doesn't feel the earth move.

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One shoots a cannonball into the air. It doesn't fall to the west. The earth would be moving. According to Galileo, it's some 1000 miles 1000 MPH. Of course, these are not necessarily critical concerns, but common sense is critical. Secondly, in terms of the observations of the heavens, um, there's nothing to demonstrate that the Copernican system is correct.

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Galileo suggested the phases of Venus where it goes through a crescent form and face as the moon does. In my theory, in my model, that is perfectly consistent as well. A third main concern, of course, is Scripture. Um, but before you bring up my unfortunate dealings with the church, you have provided me an opportunity to ask Tico bry, a question that I had long desired to ask him.

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Namely once you demonstrated that Ptolemy's spheres you remember those crystalline spheres that people used to believe in long ago. Indeed I do. I shattered them. Yes. In fact, it was he and his work that showed us that there were no such things as crystalline spheres in the heavens carrying the planets around in their orbits.

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I disagree with Aristotle and Ptolemy. Fine. When you destroyed those, I've always wanted to know how you explained why they were still carried in some kind of regular pattern. They obviously are not running around up there loose and going hither. And John, they are following a definite order.

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Now what accounts for that in your system? Can you tell me that, sir? I admit it is a good point suggests two main observations that separate my career, where with your telescope, you made no clearer, more precise observations of the planets. I spent time carefully quantifying the motion of the planets.

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I also observed the great star of 15 72 demonstrating that there is change in the heavens, contrary to Aristotle. And I demonstrated through parallax arguments very simple arguments that the stars above the sphere of the moon. Most importantly, and to your question, I demonstrated that the great comet of 15 77 moves in the area above the moon, contrary to Aristotle and I hasten to add Galileo, contrary to your published beliefs, The question, though, is what makes the planets move.

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And my response is, I don't know Galileo, and I find that to be a great deficiency in your system, sir. I find it a deficiency to assume a conclusion rather than to demonstrate it. Why do the heavenly bodies move? Is there a prime mover, Galileo, Do you believe that there is a first or prime mover, which is the ultimate causation of all movement?

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Well, no, not in the old sense. You see, uh, Aristotle taught that whenever you have motion that something must be causing that motion. All motion has a movement. I think he was wrong. And I have suggested as a means of correcting this deficiency that I am trying to unearth here of Tika Brize.

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I think that there is one case in which there is motion and there is no mover and that is motion at a uniform velocity in a perfect circle. If we have that kind of motion, I think that that is an equivalent state of being if I'm a wax philosophical to rest and therefore you cannot tell whether you are at rest or whether you are participating in this kind of motion.

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All right, that's the law of inertia. That's correct. Later, it has become known under that rubric. But you see, if that's the case, if I am right in my assumption, then one would not feel like one was in motion. Because the Earth is turning on its axis would still mean that you might be in motion since being at motion in this way and being at rest would be equivalent states of being, and there'll be no discernible way from within the system to tell that you were in one or the other state.

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Doesn't that position place you in jeopardy with the Catholic Church to which you belong? A church which holds, for example, to the Aristotelian philosophy and to Thomas Aquinas is reading of that philosophy. Quinn has developed proofs for the existence of God, one of which holds that nothing is moved.

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Niecy motivator, Abba Leo and less moved by another. And ultimately all movement must go back to a prime mover. Who is God? You now take the ground away from that argument. Tico is nodding. I quite agree. Uh, it's It's illogical that there should not be a prime mover of first cause.

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And if you assume an inertial, as you call it form of motion, it defies common sense and the logic of the origin of things. For example, when I push a cart or push a chair, Aristotle says with a quickness that the chair will continue to move, so long as I push it, you suggest that once I push it, it will continue to go on forever.

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That's absurd is contrary to experience Galileo that it fails the I. I understand that your that your objection is raised from within the realm of our ordinary experience. I understand also that I am stating a condition, which is, I suppose, somewhat abstract. It's not sensible, it's nonsensical now.

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I disagree that it is non sensible in the sense that it makes no consistent system. I believe that it does make a consistent system. For example, not only does it justify the Copernican position by answering why such things as a ball thrown upward does not come back down at a point far distant from the one that from which it was thrown.

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If the earth is moving under it, that should happen. It does not happen. Why? Because this rock and the earth are both participating in the same motion. They are carried together in their revolution, around the sun and in their rotation. That is a perfectly consistent system, and it not only is consistent, but it answers that major deficiency of your system.

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That is when I have asked the question of myself. Why, in fact, do the planets continue to go around when there are no crystalline spheres to carry them? It is natural for them, so to do, they are merely exhibiting this natural state of motion that I claim exists.

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Uh huh. When you published the Starry Messenger in 16 10, I believe you told correct there were many objections to your theories from the Aristotle Ian's in the schools, academies and universities. They held that your theory could not possibly be sustained because if the Earth moved, we would leave the moon behind us.

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How do you respond to that? Well, again, I would respond in the same way that the Earth and the moon are a system. The er moon is revolving around the earth. The earth is revolving around the sun. Both of them participate in this perfect inertial motion circular inertial motion, and that that requires no explanation because it is as natural as rest.

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If you find it necessary to explain why something is at rest, then perhaps you would find it necessary to explain why something is in this kind of motion. I find no reason to explain why something is at rest. It is at rest because it is at rest.

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And likewise these objects are in their systematic motions because they are in this natural state. Tico, you base a part of your theory on Scripture that is the Hebrew Scriptures and the Christian New Testament. I wonder if you are not referring to just one or two moments in Scripture as, for example, when Joshua commanded the sun to stand still.

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Am I correct that you're referring to just a few such incidents as these, which might have been mythological or figurative in nature? Perhaps we would grant that I base my argument on observation, and I see no observational proof for Galileo's position. I base it on accuracy, and I see none, no greater convenience with that of Copernicus.

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I base it on common sense, and I base it on Scripture to be sure. The scripture speak of, for example, the four corners of the earth. And we know the Earth spherical. By the same token, the Scriptures raised the point that we should not proliferate hypotheses.

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So I used that point against Galileo in the following sense. We would grant, for example, in the cabin of a moving ship, and if you were to play cards that the cards would would move, they would move with the ship. They would not fall behind. I would grant if the Earth were to move with this principle of inertia that a ball falling from the top of the tower would fall at the foot of the tower.

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But I will not grant that We must assume this to be true. For if the earth is fixed and stable, the ball will fall at the foot of the tower. We need not proliferate examples We need not get into these abstractions and absurdities of a moving earth when there is no proof this is consistent with the scripture.

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Why doubt Scripture when common sense when the observation in the simple logic of science suggests not now on that point, if I may, I wrote to the Grand Duchess Christina. Yes. On this matter of Joshua and the Sun standing still, you know, Joshua is said to have commanded the sun to stand still in the day was therefore longer.

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And it was assumed by my critics and Copernicus critics that if Joshua commanded the sun to stand still, then the sun must have been in motion. Otherwise it makes no sense to have it stand still. And if the sun is in motion, then of the two bodies, the sun and not the earth is in motion.

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Well, if you think about it, you realize that the sun's proper motion not the motion of the heavenly orb, the gigantic pro premium mobile A that you referred to a minute ago that carries the sun across the sky from day to day or night today. Not that motion.

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That's the sun's motion by virtue of its participation in this giant orb. The sun's proper motion lags behind that and is carried eastward instead of westward across the sky. If Joshua commanded the sun to stand still, I suggest then he was commanding the proper motion of the sun to cease.

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That, in fact, would mean that the sun would not lag behind that gigantic vault but would be carried even quicker toward the horizon. The day would actually be shorter. So you see, it at least means that the simple reading of that text would suggest Ptolemy must be interpreted in some kind of interesting fashion, not the clear, obvious faction fashion that my critics have suggested.

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Galileo. I cannot let this occasion pass without asking you about an incident widely attributed to you. Tico mentioned a moment ago an example of dropping an object to the base of the tower. Did you really drop to objects of unequal weight from the leaning Tower of Pisa to test Aristotle's theory that velocity is a function of weight?

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Well, let me give you a few facts, and then I will allow you to judge the matter for yourself. It would have been when I was somewhat old. I would have had to carry two gigantic, leaden balls up the tower, which was considerably high, as you know.

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And you had a double hernia all your life. I did. And therefore I suggest that these facts may in turn, provide you with enough information to make up your own mind on this matter. All right. Thank you. I I assume that you did not do the experiment widely attributed to you.

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It's part of the Galileo legend, Tico. I'm satisfied with your response. It's based upon the measurements of which you were capable at your time. But you did not have the telescope. Do you mean to say that you do not think that a new technology such as the telescope would have qualified some of the views that you expressed in your lifetime?

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I believe that's true. And I think if we were to question Galileo closely, who would admit as well that there was nothing revealed by this new marvelous instrument that demonstrated the Copernicus was correct? Certainly the claim would be made. And I suspect this is why Galileo ignored discussion of my system, that iconic system in his greatest work, the dialogue on the two chief systems of the world.

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It's curious, Galileo that you would oppose the Ptolemaic system and the Copernican system in 16. 32 when no one no one knowledgeable in these matters accepted the Ptolemaic system. I suspect you were setting up a straw man. Could you respond to that? Uh, on, I suppose.

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Uncomfortable. Galileo. Well, it's the truth. What he says may have a kernel of truth in it. That is to say, the telescope. Yes, it did make things clearer to me. I can see to someone of his ilk why they may not have had to become a Copernican simply because of what you could see with the telescope.

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I know that in his system he can account for the observations that the telescope reveals. It was not the telescope in that sense. But the reason that I did not address your system, you see, was I did not wish to make. The issue is so complicated.

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Complicated. Truth is a complicated matter, Galileo. Well, I am so firmly convinced that my new inertial principle will stand the test of time and will become part of the assumptions of every good scientist and astronomer that I deemed it unnecessary to complicate the issue at this time.

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By bringing in all of the difficulties that are associated with your system, it was easier to contrast the two major systems. Could I could I get away from the systems just for a few minutes? You both strike me as rarefied intellectual types, men who lived the life of the mind.

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And yet, at the risk of offending you, I must say I have looked in your dossiers and have discovered that you have lived very human lives. Indeed, as a matter of fact, if I may put it bluntly, I think the two of you have been womanizers.

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And what shall I say? People who have even been profligate at times tico I would admit that I am a man. Yes, I am had a number of good times as it were on the Continental trip. As a young man, Hawking and Horn was standard fare for men of noble quality.

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Unlike Galileo, who has a noble birth but noble standing, Uh, and of course, I took a common law wife and had a number of Children out of wedlock out of formal wedlock. Galileo, I think yours is something of the same type story. Well, you have to understand my position.

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You see, I was the eldest son in a family of four daughters and three sons. Now I've just taken a new position at the University of Pisa. Within three years my father died. That left me the responsibility of providing a dowry for all four of my sisters.

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It was a difficult life. I never had a good financial standing until later, when the starry messenger assisted me in Prague and, uh, obtaining the patronage of the Grand Duke. But early in my life, I needed some diversity of pleasure, and I did find and establish a very meaningful relationship with a woman who, incidentally, provided me with three Children, a son and two daughters, and I suppose you count it redemptive.

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that both of the daughters became nuns. Well, I did take a certain gratification in that. Mhm. You also didn't have to pay dowries. Galileo. Yes, I'll let that pass. Galileo, why did you not obey the good counsel given you by Pope Urban the eighth, Which was, as you recall, that you hold to your theory as a hypothesis only and not attempt to propagate your doctrine as proven fact.

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But, you see, he would have escaped censure, condemnation and a possible you almost went to jail over this very good sense. Go to jail. I was confined to my house. Yes. Excellent question. Well, I did. You see, I did do all of those things in my own mind.

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Maffeo Barberini. I knew him before he became pope as cardinal and Barberini and I had had talked about things even after he became Pope Urban the eighth. I went to Rome and had six long conversations with him. And I thought we were of one mind on this matter.

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You see, when the church representative Cardinal Bellarmine had called me in 16 16 to clarify certain of these issues that were of concern to the clergy and to the hierarchy of the Catholic Church. Well, I was told at that time that I was not to teach or defend.

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Now, in my book, the one for which I was censured, I did not teach an orphan or nor defend. I had a discussion among three interlocutors and we discussed objections to the theory and people were allowed to make their own mind. I did not think that I was teaching or defending anything.

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And consequently I was greatly surprised, humiliated, shocked to learn that I had offended where I had not sought to as well. You would, Galileo. You put the words of the pope in the mouth of Simplicio. That was perhaps my most unfortunate error. Yes, that was an error of judgment, I believe.

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And it led to numerous troubles which pursued you until your death. That's correct. You spent your last year's in house arrest under house arrest. I went blind. It was not a pleasant time, although I did work on some really good scientific works that have stood the test of time.

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And now, gentlemen, if we may pass from one dimension to another, namely the present, may I identify two of you as Professor Robert Hatch of the Department of History in the College of Liberal Arts and Sciences at the University of Florida, and Professor Gregory of the ST Apartment Professors of the History of Science, possible by a grant from W.

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L. U s featuring the music of your life, US 98.