WEBVTT 1 00:00:00.000 --> 00:00:06.020 Good afternoon, ladies and gentlemen, and welcome to this penultimate session of the Adelaide Festival of Ideas. 2 00:00:06.460 --> 00:00:14.540 My name's Paul Davies, and it's my pleasure and honor to chair the meeting this afternoon with Owen Gingrich. 3 00:00:15.320 --> 00:00:18.160 Just a couple of housekeeping points before we begin. 4 00:00:18.600 --> 00:00:21.520 As ever, please turn off your mobile phones now. 5 00:00:23.120 --> 00:00:25.580 Secondly, there is a time factor. 6 00:00:25.580 --> 00:00:33.800 Because of the final session, which will be in this hall, which begins at 5 o'clock, we must depart sharp at 4.30. 7 00:00:35.060 --> 00:00:40.320 Owen's presentation will last just about an hour, which leaves us 15 minutes for questions, 8 00:00:40.460 --> 00:00:47.640 but we must keep those questions short and snappy, and must discourage people from coming forward at the end, 9 00:00:47.680 --> 00:00:54.280 because this will impede the attempts by the organizers to get the hall cleared and ready for the last session. 10 00:00:54.480 --> 00:00:55.560 So, if I could just... 11 00:00:55.580 --> 00:01:01.300 If I could just ask for your patience and cooperation in basically getting out fast at the end. 12 00:01:02.820 --> 00:01:08.140 Now, Owen Gingrich is an astronomer by profession. 13 00:01:08.280 --> 00:01:16.020 He works at Harvard in the United States, where he holds the dual positions of Senior Astronomer Emeritus 14 00:01:16.020 --> 00:01:23.880 at the Smithsonian Astrophysical Observatory, and he's Research Professor of Astronomy and the History of Science at Harvard University. 15 00:01:24.380 --> 00:01:25.560 So, he mixes... 16 00:01:25.580 --> 00:01:32.700 He mixes an interest in contemporary astronomical research with the history of science in general and astronomy in particular. 17 00:01:33.600 --> 00:01:37.120 And the subject of his presentation this afternoon is Galileo, 18 00:01:37.120 --> 00:01:43.340 who many commentators believe was, in some sense, the father of modern science as we know it. 19 00:01:43.480 --> 00:01:48.080 So, tremendously important, but also controversial figure in the history of science, 20 00:01:48.140 --> 00:01:54.420 not least because of his perceived clash with the established church at that time. 21 00:01:55.580 --> 00:02:01.100 I'm quite sure that Owen, as a magnificent scholar in this field, 22 00:02:01.200 --> 00:02:08.220 is going to put an interesting and personal interpretation on the life and work of Galileo and his relationship to the church. 23 00:02:08.360 --> 00:02:13.420 And I'm very much looking forward to hearing what he has to say and to seeing the slides. 24 00:02:14.520 --> 00:02:17.880 And just one thing that occurs to me as an afterthought standing here, 25 00:02:18.460 --> 00:02:20.880 and this is a remark to the organizers, 26 00:02:21.560 --> 00:02:25.300 I will remember the last Adelaide Festival of Ideas being in this hall, 27 00:02:25.580 --> 00:02:28.920 and the slides were rather badly affected by the house lights. 28 00:02:29.180 --> 00:02:34.460 I don't know if it's too late to just appeal to these lights at the front being turned down, 29 00:02:34.500 --> 00:02:36.800 if that's not already been taken care of, 30 00:02:36.900 --> 00:02:41.820 because I think it will prove a bit of a problem for people at the back seeing the slides on the screen. 31 00:02:42.000 --> 00:02:46.620 So, if anybody's in control of those lights, perhaps I'd be kind enough to dim them. 32 00:02:47.400 --> 00:02:51.020 Anyway, without further ado, I will hand you over to Owen Gingrich. 33 00:02:51.820 --> 00:02:53.480 Thank you very much. 34 00:02:59.460 --> 00:03:01.620 Thank you very much, Paul. 35 00:03:03.340 --> 00:03:09.500 In both America and Australia today, among those of us who take the Bible seriously, 36 00:03:09.960 --> 00:03:16.980 there is a wide spectrum of opinion and considerable tension over how scriptures should be interpreted. 37 00:03:17.940 --> 00:03:20.940 Did God really create the world in just six days? 38 00:03:21.460 --> 00:03:25.560 Must we believe that a 500-year-old man put two of every three in one book? 39 00:03:25.580 --> 00:03:31.960 A very kind of creature plus a year's supply of food into a closed wooden ship 500 feet long? 40 00:03:32.580 --> 00:03:36.840 Must we accept that the earth is fixed in a geocentric universe? 41 00:03:37.300 --> 00:03:40.120 After all, Psalm 104 says, 42 00:03:40.460 --> 00:03:44.840 The Lord God laid the foundation of the earth that it not be moved forever. 43 00:03:46.100 --> 00:03:52.300 And that was one of the proof texts that was very commonly used in the 17th century. 44 00:03:53.460 --> 00:03:55.560 In the 16th and 17th, 45 00:03:55.580 --> 00:04:00.080 17th centuries, which is the setting for my story this afternoon, 46 00:04:00.420 --> 00:04:06.480 there was, as today, considerable ferment over how the Bible should be interpreted. 47 00:04:06.800 --> 00:04:12.160 The Catholic Church had long taught that the scriptures were credentialed and understood 48 00:04:12.160 --> 00:04:14.960 through the commentaries of the church fathers. 49 00:04:15.740 --> 00:04:23.760 But in 1514, young Martin Luther performed an audacious hermeneutical act. 50 00:04:24.720 --> 00:04:25.560 He published the... 51 00:04:25.580 --> 00:04:28.880 The text of the Psalms with wide white margins, 52 00:04:30.000 --> 00:04:35.040 omitting the standard glosses from Augustine, Origen, and the other early authorities. 53 00:04:35.760 --> 00:04:40.160 The long standard allegorical interpretations were challenged. 54 00:04:41.180 --> 00:04:42.780 Civil history had been discovered. 55 00:04:43.140 --> 00:04:47.120 And Moses was seen as the first and most accurate historian. 56 00:04:48.020 --> 00:04:54.700 It's against this background that the so-called Galileo affair played out. 57 00:04:56.480 --> 00:05:02.260 Perhaps I can sharpen this just a little bit by reading a paragraph from a recent book 58 00:05:02.260 --> 00:05:06.340 by the Brown University biochemist Ken Miller, 59 00:05:06.580 --> 00:05:09.820 a book entitled Finding Darwin's God. 60 00:05:11.100 --> 00:05:14.760 The imagination of an age is shaped by its experiences. 61 00:05:15.260 --> 00:05:20.080 And these, in turn, are colored by its knowledge and understanding of the natural world. 62 00:05:21.020 --> 00:05:25.340 For thousands of years, humankind thought itself the focus of the universe. 63 00:05:25.580 --> 00:05:29.780 Watching the sun and moon revolve around a human center. 64 00:05:30.580 --> 00:05:35.100 And picturing the stars as decorations on a distant ceiling of the nighttime sky. 65 00:05:36.140 --> 00:05:40.260 This view was confirmed by a story of origins, 66 00:05:40.940 --> 00:05:45.080 detailing our species and all others brought abruptly into existence 67 00:05:45.080 --> 00:05:47.580 by the direct action of the creator. 68 00:05:48.300 --> 00:05:51.360 The great legacy of the scientific age 69 00:05:51.360 --> 00:05:55.120 is the understanding that neither of these stories 70 00:05:55.120 --> 00:05:55.560 are the same. 71 00:05:55.580 --> 00:05:56.880 The science of the universe is scientifically correct. 72 00:05:59.340 --> 00:06:02.660 For a dozen centuries, 73 00:06:03.880 --> 00:06:06.840 God was seen as the lord of a great manner, 74 00:06:07.740 --> 00:06:10.300 sitting just beyond the sphere of stars. 75 00:06:11.980 --> 00:06:14.760 When the idea, the heliocentric idea, 76 00:06:15.040 --> 00:06:19.500 of placing the sun and not in the center of the universe came about, 77 00:06:20.460 --> 00:06:24.460 there was always kind of implicitly in the background 78 00:06:29.260 --> 00:06:54.540 about the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the creator of the universe as the 79 00:06:54.540 --> 00:06:58.140 how do you interpret these things, what are their relative stands, 80 00:07:00.160 --> 00:07:08.860 was also a battle of turf as to who had the right to declare what was true. 81 00:07:10.880 --> 00:07:17.520 That story, the one about the arrangement of the heavens, has long since played out, 82 00:07:17.600 --> 00:07:22.300 and I don't think we have very much debate about it now. 83 00:07:22.300 --> 00:07:29.980 Now, the other story about the origin of the species is one that is still very controversial 84 00:07:29.980 --> 00:07:32.620 and is still playing out in controversy. 85 00:07:33.060 --> 00:07:36.280 And I think there are certain kinds of parallels in this story, 86 00:07:36.380 --> 00:07:39.140 and I'm not going to draw those parallels explicitly, 87 00:07:40.160 --> 00:07:45.220 but instead what I'm going to do is concentrate on the story of Galileo 88 00:07:45.220 --> 00:07:49.740 and try to paint it with a certain palette of grays, 89 00:07:49.740 --> 00:07:52.280 rather than in the stark black and white. 90 00:07:52.300 --> 00:08:02.300 In the central cosmological chapter of his De Revolutionibus, 91 00:08:03.060 --> 00:08:04.300 Copernicus exclaims, 92 00:08:07.820 --> 00:08:20.060 Well, of course, that was a rhetorical question not intended to be answered, 93 00:08:20.180 --> 00:08:21.780 because virtually everybody, 94 00:08:22.300 --> 00:08:26.780 would have said, yes, it must go some other place. 95 00:08:27.160 --> 00:08:30.680 Namely, out there, going around the earth every day. 96 00:08:30.760 --> 00:08:36.200 The whole notion that the earth is spinning on its axis every 24 hours 97 00:08:36.200 --> 00:08:37.740 seemed totally ridiculous. 98 00:08:38.480 --> 00:08:42.920 I mean, after all, if it's doing that and you throw a stone up in the air, 99 00:08:43.540 --> 00:08:46.400 it's going to land miles away. 100 00:08:48.200 --> 00:08:52.200 We know, just from our senses, that the earth is solidly fixed. 101 00:08:52.300 --> 00:08:58.740 And the interesting thing is that when Copernicus published his book in 1543, 102 00:08:59.020 --> 00:09:01.840 he had no proof of the earth's motion. 103 00:09:02.200 --> 00:09:07.120 It was essentially for him a theory pleasing to the mind. 104 00:09:07.320 --> 00:09:09.860 Something that he saw in mind's eye. 105 00:09:10.060 --> 00:09:12.300 A beautiful aesthetic view. 106 00:09:13.700 --> 00:09:18.480 And it explains some things much better than before, 107 00:09:18.600 --> 00:09:22.240 as far as the celestial mechanics and the appearances of the planet. 108 00:09:22.240 --> 00:09:22.960 And it's not just the planets were concerned, 109 00:09:23.200 --> 00:09:28.720 but it seemed just completely out of it when it came to the physics. 110 00:09:31.100 --> 00:09:34.500 Did Copernicus believe in the reality of his system? 111 00:09:36.600 --> 00:09:41.660 When the book was published, there was an anonymous preface added at the printers. 112 00:09:42.600 --> 00:09:47.560 The clergyman who had been hired as a proofreader in Nuremberg 113 00:09:47.560 --> 00:09:52.060 was brought in to write a kind of a, 114 00:09:52.240 --> 00:09:54.700 little document to help protect the book. 115 00:09:55.660 --> 00:09:59.820 He said, you may have heard something about the hypotheses in this book, 116 00:09:59.940 --> 00:10:03.940 and are afraid that all of liberal arts are about to be thrown into confusion. 117 00:10:04.160 --> 00:10:05.780 But don't worry about that. 118 00:10:06.040 --> 00:10:10.260 It's the astronomer's job to make observations, 119 00:10:11.080 --> 00:10:18.460 and then to make hypotheses to be able to predict the positions of planets at any time. 120 00:10:18.940 --> 00:10:21.960 But these hypotheses need not be true, 121 00:10:22.240 --> 00:10:23.220 nor even probable. 122 00:10:24.300 --> 00:10:27.420 Perhaps a philosopher will seek after truth, 123 00:10:27.680 --> 00:10:30.660 but an astronomer will just take what's simplest. 124 00:10:31.500 --> 00:10:36.000 And neither will know anything true unless it's been divinely revealed to him. 125 00:10:37.000 --> 00:10:41.160 So therefore, if you're entering expecting to find truth, 126 00:10:41.360 --> 00:10:44.780 beware lest you leave a greater fool than when you entered. 127 00:10:45.540 --> 00:10:50.120 Now the question is, would Copernicus have subscribed to that? 128 00:10:50.760 --> 00:10:52.220 He saw it for the first time. 129 00:10:52.240 --> 00:10:54.620 On his deathbed, 130 00:10:54.740 --> 00:10:58.440 when the final pages of the book were brought back to him in Poland. 131 00:10:59.120 --> 00:11:01.020 We can't be quite sure. 132 00:11:01.880 --> 00:11:03.440 But what we do know, 133 00:11:03.460 --> 00:11:05.580 is that Johannes Kepler, 134 00:11:05.800 --> 00:11:11.220 the first astronomer to write an enthusiastic Copernican treatise, 135 00:11:11.220 --> 00:11:12.560 after Copernicus himself, 136 00:11:13.500 --> 00:11:15.500 was a realist, 137 00:11:15.520 --> 00:11:16.980 believed it was real, 138 00:11:17.120 --> 00:11:19.220 and believed it was a physical description. 139 00:11:19.820 --> 00:11:22.020 And I think the same thing, 140 00:11:22.020 --> 00:11:23.940 was true of Galileo. 141 00:11:25.300 --> 00:11:31.920 It's exactly why Galileo accepted this strange idea. 142 00:11:32.160 --> 00:11:37.460 Well, I suspect it has to do with the psychological impact 143 00:11:38.020 --> 00:11:40.960 of a device which he found out about. 144 00:11:41.580 --> 00:11:42.240 He had been, 145 00:11:43.020 --> 00:11:44.920 he had written a letter to Kepler, 146 00:11:45.000 --> 00:11:47.300 said he was secretly a Copernican, 147 00:11:47.400 --> 00:11:49.340 but he wasn't public about it, 148 00:11:49.360 --> 00:11:51.240 and as he was teaching in Padua, 149 00:11:51.240 --> 00:11:56.260 he taught the standard geocentric system with the fixed earth. 150 00:11:57.760 --> 00:11:59.620 Now if we can go to the slides, 151 00:11:59.760 --> 00:12:01.960 I'll show you Galileo himself. 152 00:12:02.400 --> 00:12:04.060 A very bright-eyed, 153 00:12:04.200 --> 00:12:06.720 red-haired fellow. 154 00:12:07.440 --> 00:12:10.820 He had been born in Pisa, 155 00:12:10.940 --> 00:12:12.860 had gone to school there. 156 00:12:13.080 --> 00:12:14.880 He was sent by his father. 157 00:12:15.060 --> 00:12:16.520 His father was a musician. 158 00:12:16.720 --> 00:12:20.020 His father knew that music was not a good way to make a living. 159 00:12:20.160 --> 00:12:21.220 He wanted his son to be a musician. 160 00:12:21.240 --> 00:12:22.200 He wanted his son to be a doctor. 161 00:12:24.240 --> 00:12:26.940 Galileo was totally bored with medical studies, 162 00:12:27.080 --> 00:12:29.540 and there was a little family fracas, 163 00:12:29.600 --> 00:12:33.660 and then it worked out that his father allowed him to study mathematics. 164 00:12:34.060 --> 00:12:37.200 He became an assistant professor there at Padua. 165 00:12:37.400 --> 00:12:41.240 He was so feisty and controversial that he didn't get tenure. 166 00:12:42.200 --> 00:12:47.620 So he was lucky he found another job over in Padua, 167 00:12:47.760 --> 00:12:48.880 and it was there, 168 00:12:48.880 --> 00:12:51.220 where he had been teaching for some years, 169 00:12:51.240 --> 00:12:57.840 when he heard about that there were peddlers going around with a spyglass, 170 00:12:58.280 --> 00:13:00.980 something that made distant objects closer. 171 00:13:01.180 --> 00:13:02.200 He didn't see one, 172 00:13:02.320 --> 00:13:05.600 but he figured out by himself how to do it. 173 00:13:05.760 --> 00:13:07.260 And he was, 174 00:13:09.080 --> 00:13:13.980 he began to work with lenses and make the telescopes better and better. 175 00:13:14.140 --> 00:13:17.200 And I use the word telescope anachronistically, 176 00:13:17.360 --> 00:13:19.400 because it didn't have that name for a bit. 177 00:13:19.520 --> 00:13:21.220 The next slide will inform you. 178 00:13:21.220 --> 00:13:23.040 And he did, in fact, show us two of the telescopes. 179 00:13:27.220 --> 00:13:30.320 It's amazing because he made probably a hundred of them, 180 00:13:30.380 --> 00:13:33.680 distributing them among the nobility of Europe. 181 00:13:34.080 --> 00:13:41.980 And it's strange that only these two are authentic examples that have survived. 182 00:13:42.340 --> 00:13:46.900 I think there's a negotiation going on about getting some of the lights down. 183 00:13:47.180 --> 00:13:49.200 Yo-ho, let's have the next slide. 184 00:13:49.320 --> 00:13:49.760 Thank you. 185 00:13:51.220 --> 00:13:53.860 There you can see the two authentic examples, 186 00:13:54.120 --> 00:13:58.160 which are preserved at the History of Science Museum in Florence. 187 00:13:58.720 --> 00:14:03.000 Amazing that there are only the two Galilean telescopes still remaining. 188 00:14:04.500 --> 00:14:08.120 He demonstrated it to the members of the Senate. 189 00:14:08.240 --> 00:14:11.380 He was there in nearby Venice. 190 00:14:12.220 --> 00:14:16.280 He was, of course, hoping for some substantial honorarium. 191 00:14:16.360 --> 00:14:18.300 It was basically a military secret. 192 00:14:18.300 --> 00:14:24.540 You could see ships coming in long before you could get them with your naked eye, 193 00:14:24.660 --> 00:14:26.020 if you had this device. 194 00:14:26.540 --> 00:14:32.440 But Galileo was filled with curiosity, and so he turned it to the moon. 195 00:14:33.020 --> 00:14:39.700 And the next slide will show you what he saw in November of 1609. 196 00:14:40.540 --> 00:14:43.100 He took this piece of watercolor paper. 197 00:14:43.380 --> 00:14:47.300 He drew the crescent moon as it was hanging in the waves. 198 00:14:47.300 --> 00:14:49.920 He drew the crescent moon as it was hanging in the waves. 199 00:14:49.920 --> 00:14:54.400 He drew it with these little dots along the edge with such accuracy 200 00:14:54.400 --> 00:14:59.600 that it's possible to get the exact date of his observation, 201 00:14:59.860 --> 00:15:04.420 even though there's no date here. 202 00:15:04.620 --> 00:15:07.000 He made a second drawing the same evening. 203 00:15:08.020 --> 00:15:10.140 And then the next night he came out. 204 00:15:10.160 --> 00:15:14.800 By that time the moon was a little bit higher toward the southwest, 205 00:15:14.800 --> 00:15:18.520 so he turned his page the other way with this side up. 206 00:15:18.640 --> 00:15:19.840 He drew another one. 207 00:15:20.540 --> 00:15:25.720 And then a night or so later he drew another one down here. 208 00:15:25.820 --> 00:15:28.260 You see he's putting it in in this random kind of order. 209 00:15:28.440 --> 00:15:33.420 So I think this is the original sheet on which he made these washed drawings. 210 00:15:33.820 --> 00:15:37.700 There's no text, but it was interesting because he realized 211 00:15:37.700 --> 00:15:41.680 that these little spots of light were the tops of mountains 212 00:15:41.680 --> 00:15:44.780 with the sunlight just clipping them. 213 00:15:44.800 --> 00:15:46.760 Only illuminating the peak. 214 00:15:47.120 --> 00:15:50.480 And he was clever enough to see that with a little mathematics 215 00:15:50.480 --> 00:15:55.340 he could actually make a calculation as to how high the mountain must be. 216 00:15:56.160 --> 00:16:00.760 But apart from that, he didn't really have much to write about. 217 00:16:02.500 --> 00:16:11.120 Then in January of 1610, he turned his instrument to the planet Jupiter, 218 00:16:11.400 --> 00:16:14.540 which soon after sunset was very bright. 219 00:16:14.800 --> 00:16:16.100 And so he started looking for some light in the southeastern sky. 220 00:16:16.420 --> 00:16:19.000 And the next slide will show us what I consider 221 00:16:19.000 --> 00:16:24.780 to be the most exciting single page of manuscript in the history of science. 222 00:16:25.320 --> 00:16:31.300 Because this is a page in which he wrote night after night about his observations. 223 00:16:32.600 --> 00:16:35.100 I'm not sure if you can see it very easily, 224 00:16:35.260 --> 00:16:37.860 because even I have some trouble making it out, 225 00:16:37.940 --> 00:16:42.920 but here is the planet with a little companion, 226 00:16:44.800 --> 00:16:52.960 side and one on the other. He was surprised to see these little stars, and so, he says, guided by 227 00:16:52.960 --> 00:16:59.160 what fates he knew not, he went out and looked again the next night. And now he was very much 228 00:16:59.160 --> 00:17:05.600 surprised to find that all three of the little companions were on the other side. Surprised 229 00:17:05.600 --> 00:17:11.080 because he thought the planet was moving the other direction. So he was puzzled about that, 230 00:17:11.080 --> 00:17:19.060 and therefore came out again to take another look. The next night, there were only two, and on the 231 00:17:19.060 --> 00:17:26.920 other side, he figured one was behind the planet. He tried the next night, it was cloudy. So then, 232 00:17:26.940 --> 00:17:34.140 the next night, and now he's got, again, one on one side and two on the other. So now he's getting 233 00:17:34.140 --> 00:17:39.140 in earnest about this, and you see there's more text, because he's writing up more carefully 234 00:17:39.140 --> 00:17:41.060 what it was he was seeing. 235 00:17:41.080 --> 00:17:49.120 He tried again, and then again, and then this night, he got four of them, not just three. Three on one 236 00:17:49.120 --> 00:17:56.740 side, one on another, and then he says, or better, and he draws it again with a little care about the 237 00:17:56.740 --> 00:18:04.360 exact spacing of them. Because now, he's beginning to get the idea that these are companions, and 238 00:18:04.360 --> 00:18:09.620 they're accompanying the planet, and they're going around, and maybe he can begin to identify them. 239 00:18:09.800 --> 00:18:11.060 And so, here again, he's got four of them, and then again, he's getting in earnest about this, and 240 00:18:11.080 --> 00:18:11.280 he tries to figure out where the planet should go. So then, he tries to figure out where the planet should go. 241 00:18:11.280 --> 00:18:14.600 And so, here again, he's got four of them, and then he says, or better, and he draws it again with a little care about the 242 00:18:14.600 --> 00:18:15.060 four the next night. 243 00:18:16.260 --> 00:18:22.780 You turn the page over, the observations continue, but there's something different about the other side. 244 00:18:23.660 --> 00:18:28.140 This side of the manuscript is all in his native language, Italian. 245 00:18:29.300 --> 00:18:32.320 You go to the other side, and it's all in Latin. 246 00:18:32.900 --> 00:18:40.220 Why? Because Latin was the international language of science, and suddenly, Galileo has realized 247 00:18:40.220 --> 00:18:41.060 that he should have done something about the other side. 248 00:18:41.060 --> 00:18:47.120 has made an important discovery that is going to be worth writing about. And in fact, he rushes his 249 00:18:47.120 --> 00:18:56.080 book into print. You'll see the title page on the next slide. And then it's called the Sidereal 250 00:18:56.080 --> 00:19:05.280 Messenger, brought out by Galileo Galilei, son of Florence. Wait a minute, I just told you he was 251 00:19:05.280 --> 00:19:14.740 born in Pisa. Okay, this is a little piece of political propaganda. He is very bored with 252 00:19:14.740 --> 00:19:21.040 teaching in Padua and having to tutor students and house them and all of this coming and going. 253 00:19:21.260 --> 00:19:29.260 He was looking for a government job. He wanted to go over to the court of Cosimo de' Medici, 254 00:19:29.440 --> 00:19:34.640 the young man that he had tutored sometimes during the summer, 255 00:19:35.280 --> 00:19:44.220 and he wanted now to get a position because Cosimo had just come on the throne as the duke. 256 00:19:44.880 --> 00:19:52.060 So he's describing what he's seen with this instrument, the perspiculum, and it says about 257 00:19:52.060 --> 00:20:00.180 the spots on the moon, the circle of the Milky Way, and the four little planets, 258 00:20:00.860 --> 00:20:05.260 which are going around Jupiter, which he proposes to call... 259 00:20:05.280 --> 00:20:13.040 ta-da, the Medicean stars. You know what? It worked. He got the job. 260 00:20:15.360 --> 00:20:21.600 The duke's personal secretary wrote, you know, what salary do you want? And Galileo said, well, 261 00:20:21.640 --> 00:20:28.320 I leave it to his highness to decide this matter. I guess he sort of managed to get the hint across 262 00:20:28.320 --> 00:20:34.960 that his salary had been abruptly raised over in Venice. He had always smarted in Venice because 263 00:20:34.960 --> 00:20:35.260 his salary had been raised in Venice. He had always smarted in Venice because his salary had been raised in Venice. 264 00:20:35.260 --> 00:20:43.360 His friend had come from peace at the same time and was the professor of medicine and had three times his salary. 265 00:20:43.580 --> 00:20:57.300 And I always say, well, what's new? But there he was. But he did have a request. He didn't just want to be 266 00:20:57.300 --> 00:21:03.980 appointed the mathematician to the Grand Duke, that is to say the astronomer. He wanted to be mathematician 267 00:21:03.980 --> 00:21:05.240 and professor. He wanted to be a mathematician and professor. He wanted to be a mathematician and professor. 268 00:21:05.260 --> 00:21:12.180 Now, you'll remember in that anonymous preface to Copernicus's book, there was a little distinction 269 00:21:12.180 --> 00:21:20.320 made about the philosophers seeking after truth and the astronomers just working hypothetically 270 00:21:20.320 --> 00:21:29.800 with these mathematical models. Galileo wanted to be credentialed in order to begin to talk 271 00:21:29.800 --> 00:21:34.340 about cosmology, about how the universe might really be put together. 272 00:21:35.260 --> 00:21:43.060 When he wrote his Sidereus Nuncius, he didn't actually come out right away for the Copernican system, 273 00:21:43.120 --> 00:21:49.360 but he did say something interesting. Concerning those satellites of Jupiter, he said, 274 00:21:49.540 --> 00:21:56.120 we have here a splendid argument for taking away the scruples of those who are so disturbed in the 275 00:21:56.120 --> 00:22:01.660 Copernican system by the attendance of the moon around the earth while both complete the annual 276 00:22:01.660 --> 00:22:05.240 orbit around the sun that they conclude this system must be the only way to get to the moon. 277 00:22:05.240 --> 00:22:16.260 The answer is, if you throw the earth into orbit going around the sun every year, how in the world can it take the moon with it? 278 00:22:16.400 --> 00:22:24.620 Why doesn't the moon get lost? But, as he says, for our vision offers us four stars wandering around Jupiter 279 00:22:24.620 --> 00:22:32.900 while all together traverse a great circle around the sun. He doesn't know how Jupiter does it, but Jupiter can do it, 280 00:22:32.920 --> 00:22:35.100 and therefore the earth could do it. 281 00:22:35.240 --> 00:22:43.760 And here is an interesting kind of argument. It is not an argument that demonstrates that the 282 00:22:43.760 --> 00:22:52.080 Copernican system is true, but it is an argument that helps make the Copernican system more plausible, 283 00:22:52.800 --> 00:23:00.380 more intellectually respectable, one might say. All right, let's go on, because the next slide 284 00:23:00.380 --> 00:23:04.560 will show us what he was up to as soon as he got over there. Well, not quite. 285 00:23:05.240 --> 00:23:11.840 I just wanted to show you Cosimo in all his splendor, so you get a little bit of an idea of 286 00:23:11.840 --> 00:23:20.620 the luxuriousness of the court. And now to the next slide, which will show us a geometrical 287 00:23:20.620 --> 00:23:30.240 situation comparing the geocentric Ptolemaic system with the Copernican system. Over here 288 00:23:30.240 --> 00:23:35.040 on your left, you see a fixed earth. The sun goes around it. 289 00:23:35.240 --> 00:23:43.000 It goes around the earth every day because the whole system is spinning, but then it slowly goes 290 00:23:43.000 --> 00:23:50.220 with respect to the stars, so it gets around every year. The planet Venus travels on a large 291 00:23:50.220 --> 00:23:58.060 subsidiary circle that lies between the sun and the earth, and the center of this circle always 292 00:23:58.060 --> 00:24:05.060 keeps in line with the sun. So Venus, as it travels around here, is always reflecting 293 00:24:05.060 --> 00:24:05.220 on the sun. It's always reflecting on the earth. It's always reflecting on the earth. It's always 294 00:24:05.220 --> 00:24:09.740 reflecting its light back to the sun, and therefore you can never see a full face. 295 00:24:10.180 --> 00:24:17.680 The best you can do is see a crescent, Venus. Now, in the Copernican system, it's the earth 296 00:24:17.680 --> 00:24:23.960 that's moving, but just to show how it works, let me keep the earth here at this vantage point. 297 00:24:24.080 --> 00:24:29.860 As Venus goes around the sun, and now you see when it's on the opposite side of the sun, 298 00:24:29.980 --> 00:24:34.500 it can reflect light from its full face, and when it's over here, 299 00:24:34.500 --> 00:24:41.680 it will just show a crescent phase. So if you could look at Venus with a telescope so that you 300 00:24:41.680 --> 00:24:48.560 could see if it has phases or not, then you might be able to see what kind of phases they are and 301 00:24:48.560 --> 00:24:55.840 draw a distinction between the two schemes. So the next slide, I have deliberately made fuzzy 302 00:24:55.840 --> 00:25:01.980 to represent the way he might have been seeing Venus with his telescope, which was not all that 303 00:25:01.980 --> 00:25:04.480 great. I mean, you can easily own a pair of binoculars, but you can't see Venus with a telescope. 304 00:25:04.480 --> 00:25:07.180 So you can see that Venus is a little bit smaller than what Galileo had. 305 00:25:07.540 --> 00:25:16.240 This is Jupiter to the same scale, just so that you can see that, in fact, Venus was very small 306 00:25:16.240 --> 00:25:24.840 when he looked at it when he got to Florence at the beginning of August in 1610. You may ask, 307 00:25:24.920 --> 00:25:28.740 well, why didn't he look at it before when he was doing his Sidereus Nuncius? 308 00:25:28.820 --> 00:25:33.900 The only thing I can conclude is that Galileo really liked his sleep. I mean, there was no 309 00:25:34.480 --> 00:25:40.700 evidence of getting up before dawn to have a crack at Venus, which was then in the morning sky. 310 00:25:41.760 --> 00:25:47.260 All right. The 1st of September, still just a fuzzy blob. You could hardly tell anything, 311 00:25:47.400 --> 00:25:53.820 whether it had a phase or not. The 1st of October. The 1st of November. 312 00:25:54.740 --> 00:26:02.760 And then around November the 15th, he got a letter from a young protege who was a mathematics teacher 313 00:26:02.760 --> 00:26:03.760 over in Pisa. 314 00:26:04.480 --> 00:26:11.820 Saying, you know, you ought to turn your telescope on Venus because maybe you could sort out whether 315 00:26:11.820 --> 00:26:19.440 it's a Ptolemaic system or a Copernican system. And this threw Galileo into terror because by this 316 00:26:19.440 --> 00:26:27.300 time, the Jesuits in Rome also had the telescope. And he was afraid that they, if his protege 317 00:26:27.300 --> 00:26:32.460 Castelli could figure this out, so could Father Clavius down in Rome. 318 00:26:35.240 --> 00:26:41.780 Galileo, of course, wanted to make all of the discoveries. This was part of his personality. 319 00:26:42.640 --> 00:26:50.220 And also, he figured it was necessary for his status at the court. And now he was in a deep 320 00:26:50.220 --> 00:26:58.360 panic. I mean, if he announces it prematurely, maybe Venus is always beyond the sun and it's 321 00:26:58.360 --> 00:27:01.760 never going to show a crescent phase and it won't be Copernican at all. 322 00:27:04.480 --> 00:27:13.660 So what to do? So he got an idea. He would encode his discovery in a cryptic little Latin epigram, 323 00:27:14.320 --> 00:27:21.960 scramble the letters, write it down in a letter to Lorenzo de' Medici, Cosimo's brother, who was 324 00:27:21.960 --> 00:27:29.500 the ambassador to Prague. By that time, Kepler was the royal mathematician in Prague. And clearly, 325 00:27:30.340 --> 00:27:31.760 Lorenzo would show the 326 00:27:34.480 --> 00:27:38.960 document to Kepler. And then Kepler would go nuts trying to figure out what it said. 327 00:27:39.300 --> 00:27:45.780 So let's see it. Here's the next slide. We'll show you the letter that Galileo wrote. And here is the 328 00:27:45.780 --> 00:27:48.140 anagram at the top of the letter. It says, 329 00:27:48.280 --> 00:27:57.120 Haik imatura ame jam frustra liguntur. O-Y. Two letters left over. He wasn't able to get those 330 00:27:57.120 --> 00:28:03.680 to fit in. It means sort of these things rested from me prematurely. 331 00:28:04.480 --> 00:28:07.160 Now let's go on. The next slide will show what 332 00:28:07.160 --> 00:28:07.520 Now let's go on. The next slide will show what 333 00:28:07.520 --> 00:28:11.860 Now let's go on. The next slide will show what happened. Here is the planet on December the 1st. 334 00:28:11.860 --> 00:28:14.340 Now let's go on. The next slide will show what happened. Here is the planet on December the 1st. 335 00:28:14.340 --> 00:28:16.340 Now let's go on. The next slide will show what happened. Here is the planet on December the 1st. 336 00:28:16.340 --> 00:28:18.520 Now let's go on. The next slide will show what happened. Here is the planet on December the 1st. 337 00:28:18.520 --> 00:28:25.860 Now let's go on. The next slide will show what happened. Here is the planet on December the 1st. 338 00:28:25.900 --> 00:28:34.460 Now let's go on. The next slide will show what happened. Here is the planet on December the 1st. 339 00:28:34.460 --> 00:28:40.680 that Kepler actually published it. Interestingly, Galileo never published it at this time, 340 00:28:40.760 --> 00:28:46.560 but in a book about Galileo's discoveries, Kepler put it in. Here is where it says, 341 00:28:46.600 --> 00:28:53.280 Heike Matura, etc., and then down here he has unscrambled it. Synthiae Figurus Emulator 342 00:28:53.280 --> 00:29:00.940 Matur Amorum. Those of you who are really fast with your Latin will have got it. It says, 343 00:29:00.940 --> 00:29:11.900 The Mother of Loves imitates the shapes of Synthia. Got it? Well, it's sort of double-blind. 344 00:29:12.260 --> 00:29:18.820 The Mother of Loves is, of course, Venus, and Synthia is a classical name for the moon, 345 00:29:18.960 --> 00:29:28.880 so Venus imitates the phases of the moon. Ah, now the plot thickens. 346 00:29:29.320 --> 00:29:30.920 The next slide will show you the second slide. 347 00:29:30.940 --> 00:29:36.240 It will show us Cosimo's mother, who was sort of the power behind the throne, 348 00:29:37.040 --> 00:29:43.120 and she would have these intellectual brunches for members of the clergy, professors, and so on. 349 00:29:43.180 --> 00:29:47.600 The court, I think, was down at Pisa or something, so Castelli got an invitation, 350 00:29:49.160 --> 00:29:56.660 and Christina said, You know, how is this about these little moons around Jupiter? Are they real? 351 00:29:57.100 --> 00:30:00.840 And Castelli said, Well, of course they are. Even Father Clavius, 352 00:30:00.940 --> 00:30:08.600 has been able to confirm this. Well, she said, You know, how about this Copernican system business? 353 00:30:08.700 --> 00:30:16.720 After all, Joshua at the Battle of Gibeon did not command the earth to stop. He commanded the sun 354 00:30:16.720 --> 00:30:25.300 to stop. Oh, said Castelli, I'm sure Galileo can explain all of that. It must have come as a little 355 00:30:25.300 --> 00:30:29.420 bit of a shock to Galileo, who wasn't really very strong on church fathers, 356 00:30:30.940 --> 00:30:38.160 but so he went to work and read his Augustine and so on. The problem was no church fathers had 357 00:30:38.160 --> 00:30:43.500 really discussed heliocentrism, hadn't ever occurred to them, but there were various things 358 00:30:43.500 --> 00:30:50.220 about the interpretation of Scripture, and Galileo wrote back a letter to Castelli saying 359 00:30:50.220 --> 00:30:55.900 that the Bible is written in the language of common people so that it can be easily understood. 360 00:30:56.260 --> 00:30:59.060 It's not supposed to be a scientific textbook. 361 00:30:59.380 --> 00:31:00.740 The Bible tells 362 00:31:00.940 --> 00:31:03.680 how to go to heaven, not how the heavens go. 363 00:31:06.720 --> 00:31:10.380 It's just as wonderful in Italian as it is in English. 364 00:31:13.280 --> 00:31:20.180 Well, that document then began to circulate around a little, and some of the clergy in Florence were 365 00:31:20.180 --> 00:31:28.060 a little bit annoyed about Galileo sort of poaching on their territory, and so a copy of it 366 00:31:28.060 --> 00:31:30.280 was sent down. Next slide. 367 00:31:30.940 --> 00:31:38.480 The recipient, Cardinal Bellarmina, who was the leading theologian in Rome, and at the same time, 368 00:31:38.520 --> 00:31:43.920 Bellarmina got a little Copernican tract from a Carmelite monk in Naples, 369 00:31:44.860 --> 00:31:51.240 which had defended the Copernican system. And in his reply, the cardinal said, 370 00:31:52.000 --> 00:31:59.480 since you have little time for reading and I for writing, I shall be brief. I've often felt that I 371 00:31:59.480 --> 00:32:00.920 wished I could use that line in the Bible. I've often felt that I wish I could use that line in the Bible. 372 00:32:00.940 --> 00:32:03.580 And some of the letters of recommendation that I have to put out. 373 00:32:07.900 --> 00:32:14.180 First, I say it appears to me that your reverence and Signor Galilei did prudently to content 374 00:32:14.180 --> 00:32:19.320 yourselves with speaking hypothetically, as I have always supposed Copernicus did. 375 00:32:19.600 --> 00:32:24.780 In other words, Bellarmina had read that anonymous preface, and he thought it was Copernicus writing, 376 00:32:25.500 --> 00:32:29.960 saying that this is all just hypothetical. He goes on. 377 00:32:29.960 --> 00:32:36.140 For to say that assuming the earth moves and the sun stands still saves all of the appearances 378 00:32:36.140 --> 00:32:42.500 better than eccentrics and epicycles is to speak well. This has no danger in it, 379 00:32:42.520 --> 00:32:49.220 and it suffices for the mathematicians. But to affirm that the sun is really fixed in the center 380 00:32:49.220 --> 00:32:54.400 of the heavens and that the earth revolves very swiftly around the sun is a dangerous thing, 381 00:32:54.580 --> 00:32:59.840 not only irritating the theologians and philosophers, but by injuring our 382 00:32:59.960 --> 00:33:07.080 holy faith and making the sacred scriptures false. Notice that distinction again between 383 00:33:07.080 --> 00:33:14.100 the mathematicians and the philosophers. The mathematicians just doing their modeling, 384 00:33:14.260 --> 00:33:20.120 their mathematical hypotheses. The philosophers really worried about how it's made. 385 00:33:20.600 --> 00:33:26.280 Bellarmina goes on. If there were a true demonstration, then it would be necessary 386 00:33:26.280 --> 00:33:29.940 to be very careful in explaining scriptures that seem contradictory. 387 00:33:29.960 --> 00:33:35.580 But I do not think there is any such demonstration since none has been shown to me. 388 00:33:35.780 --> 00:33:40.760 To demonstrate that the appearances are saved by assuming that the sun is in the center 389 00:33:40.760 --> 00:33:48.100 is not the same thing as to demonstrate that in fact the sun is in the center and the earth in 390 00:33:48.100 --> 00:33:57.560 the heavens. Okay, this is a little dense. Let me review for you Aristotle's posterior analytics. 391 00:33:58.340 --> 00:33:59.760 We go on to the next. 392 00:33:59.960 --> 00:34:06.640 Slide, which will show you something about the two forms of logic. Here is induction. 393 00:34:07.160 --> 00:34:14.440 This is how we learn things, by generalizing. Robins reproduce by laying eggs, penguins reproduce 394 00:34:14.440 --> 00:34:20.320 by laying eggs, and so on down. You get enough examples and you decide that birds reproduce by 395 00:34:20.320 --> 00:34:28.940 laying eggs. Now, is this absolute truth positive? No, we haven't covered all the birds yet. There 396 00:34:28.940 --> 00:34:29.940 might be some exceptions. But we're going to go on to the next slide. 397 00:34:29.940 --> 00:34:37.600 So, we have something that's highly probable, but not guaranteed truth. If you want to get to 398 00:34:37.600 --> 00:34:44.240 guaranteed truth, you've got to use deduction. The next slide will show us an example of how you 399 00:34:44.240 --> 00:34:49.720 set up your premises. You have a major premise, like if it's raining, the streets are wet. 400 00:34:50.340 --> 00:34:57.300 And then, as a minor premise, you say it's raining. And so, you conclude that the streets are wet. 401 00:34:58.460 --> 00:34:58.980