WEBVTT 1 00:00:02.200 --> 00:00:10.560 You see, something's going to happen. What's going to happen? 2 00:00:15.480 --> 00:00:25.960 What I help? On a winter night in sixteen oh four, 3 00:00:26.519 --> 00:00:28.600 a new star burned through the velvet of the sky 4 00:00:29.600 --> 00:00:33.560 in Prague, A thin, nearsighted mathematician stood at a window 5 00:00:33.560 --> 00:00:38.320 and took notes by kindlelight. That man Johannes Kepler believed 6 00:00:38.320 --> 00:00:41.320 the heavens were legible, that number and harmony were the 7 00:00:41.320 --> 00:00:45.079 alphabet of creation. I made this episode because Keppler sits 8 00:00:45.119 --> 00:00:47.759 exactly where our show loves to work, at the scene 9 00:00:47.759 --> 00:00:51.880 where mysticism meets measurement, where sacred geometry becomes celestial mechanics, 10 00:00:52.079 --> 00:00:55.960 and we're an astrologer, school teacher, refugee, and court mathematician 11 00:00:56.359 --> 00:01:00.560 chisel law out of wonder. Kepler's life is a parable 12 00:01:00.600 --> 00:01:02.719 for anyone trying to keep faith and reason in the 13 00:01:02.759 --> 00:01:06.439 same room. He cast horoscopes to pay rent and scrapped 14 00:01:06.439 --> 00:01:09.439 circles for eclipses because the data said so. He wrote 15 00:01:09.480 --> 00:01:12.480 prayers into his proofs. He defended his mother in a 16 00:01:12.480 --> 00:01:15.640 witchcraft trial and still found the patients to compute mars 17 00:01:15.680 --> 00:01:20.959 for years. His voice, equal parts devout and defiant, tells 18 00:01:21.040 --> 00:01:23.359 us that truth is the daughter of time, and in 19 00:01:23.439 --> 00:01:27.239 his time, we let him speak tonight. We follow him 20 00:01:27.239 --> 00:01:31.560 step by step, from Wilderstadt to the lecture halls of Tubingan, 21 00:01:32.000 --> 00:01:35.400 from the platonic dreams of Mysterium Cosmographicum to the hard, 22 00:01:35.439 --> 00:01:38.680 stubborn numbers of Estronomia Nova, from the music of the 23 00:01:38.719 --> 00:01:42.040 spheres and Harmonisius Mundi to the glass and light of Diopters. 24 00:01:42.359 --> 00:01:46.120 From Graz to Prague to Linn's to Ulm, carrying tables, 25 00:01:46.319 --> 00:01:49.120 depths and a vision of order that outlived the Thirty 26 00:01:49.200 --> 00:01:53.040 Years War. We're here to read Kepler in his own words, 27 00:01:53.400 --> 00:01:56.079 to place him in the world. He walked mud streets, 28 00:01:56.280 --> 00:02:00.239 church bells, printing presses, played cards, and to ask what 29 00:02:00.359 --> 00:02:04.280 his laws, his optics, his reformed astrology, and his lunar 30 00:02:04.319 --> 00:02:08.759 dream mean for art, ritual and the modern imagination. If 31 00:02:08.759 --> 00:02:11.400 you ever looked up and felt that hush, the sense 32 00:02:11.479 --> 00:02:15.599 the sky isn't just scenery but syntax, this is your episode. 33 00:02:16.159 --> 00:02:19.599 Johannes Kepler lived from fifteen seventy one to sixteen thirty 34 00:02:19.919 --> 00:02:22.159 and he lived in an age of religious turmoil and 35 00:02:22.240 --> 00:02:27.159 scientific rebirth. He was a German astronomer, mathematician, astrologer and 36 00:02:27.280 --> 00:02:31.520 natural philosopher, a visionary who helped transform Renaissance s mysticism 37 00:02:31.759 --> 00:02:36.240 into empirical science of the Scientific Revolution. Kepler is best 38 00:02:36.280 --> 00:02:39.919 known for discovering the laws of planetary motion, foundational principles 39 00:02:39.960 --> 00:02:43.199 that guided later scientists like Isaac Newton towards the theory 40 00:02:43.240 --> 00:02:47.280 of gravity. But Kepler was more than a mathematician. He 41 00:02:47.360 --> 00:02:50.360 was a man of deep faith and imagination, convinced that 42 00:02:50.400 --> 00:02:54.360 the cosmos was an orderly creation imbued with meaning. Those 43 00:02:54.479 --> 00:02:57.919 laws of nature are within the grasp of the human mind. 44 00:02:58.560 --> 00:03:01.520 God wanted us to recognize by creating us after his 45 00:03:01.599 --> 00:03:04.680 own image, so that we could share in his own thoughts. 46 00:03:05.439 --> 00:03:08.639 Kepler wrote expressing the belief that deciphering the heavens was 47 00:03:08.639 --> 00:03:12.439 a way to think God's thoughts after him. His life's 48 00:03:12.479 --> 00:03:15.439 work was driven by this almost spiritual quest for cosmic 49 00:03:15.479 --> 00:03:20.080 harmony and truth. And telling Kepler's story one finds a 50 00:03:20.159 --> 00:03:23.120 narrative as dramatic as the times in which he lived. 51 00:03:23.680 --> 00:03:27.080 He witnessed the fading of old certainties, the geocentric Earth, 52 00:03:27.319 --> 00:03:31.280 Earth centered universe, and the sharp divide between science and superstition, 53 00:03:31.680 --> 00:03:35.080 and he helped usher in new understanding, grounding, and observation 54 00:03:35.479 --> 00:03:41.039 geometry and physics. Yet Kepler's path was not easy. He 55 00:03:41.159 --> 00:03:45.680 endured war, religious persecution, personal tragedies, and even a witchcraft 56 00:03:45.759 --> 00:03:50.080 trial against his own mother. Through it all, he remained 57 00:03:50.120 --> 00:03:54.599 scrupulously honest to the data and to his convictions. The 58 00:03:54.680 --> 00:03:58.080 result was a legacy that spans astronomy and optics, music 59 00:03:58.120 --> 00:04:02.759 and mysticism, religion and philosoph This episode follows Kepler's journey 60 00:04:02.879 --> 00:04:07.000 chronologically from his humble beginnings and education, through his wanderings 61 00:04:07.000 --> 00:04:10.840 across Europe in search of intellectual refuge, to his scientific triumphs, 62 00:04:11.039 --> 00:04:14.719 while also exploring the rich tapestry of influences, ideas, and 63 00:04:14.840 --> 00:04:18.879 historical events that shaped his work. As we shall see, 64 00:04:19.000 --> 00:04:22.800 Kepler much preferred the sharpest criticism of a single intelligent 65 00:04:22.879 --> 00:04:26.040 man to the thoughtless approval of the masses, forging a 66 00:04:26.120 --> 00:04:29.560 unique path that married rigorous science with a profound sense 67 00:04:29.560 --> 00:04:35.839 of wonder. Johannes Kepler was born on December twenty seventh, 68 00:04:36.000 --> 00:04:39.839 fifteen seventy one, and the small Swabian town of Weilderstadt 69 00:04:39.839 --> 00:04:43.519 in the Holy Roman Empire in modern Germany. He came 70 00:04:43.560 --> 00:04:47.399 from a modest and tumultuous family background. His father, Heinrich 71 00:04:47.439 --> 00:04:50.480 Keppler was a mercenary soldier who left home when Johannes 72 00:04:50.560 --> 00:04:53.839 was young and likely died abroad by fifteen seventy seven, 73 00:04:53.959 --> 00:04:57.240 and his mother, Katharina Goldenman, was the daughter of an 74 00:04:57.279 --> 00:05:01.519 innkeeper known for her herbal remedies and folkilling. The Kepler 75 00:05:01.560 --> 00:05:06.759 family had been respected in earlier generations. Johannas's grandfather, Sebald Kepler, 76 00:05:06.959 --> 00:05:09.480 had even served as mayor of their city, but by 77 00:05:09.519 --> 00:05:13.800 the time of Johanna's birth, their fortunes had dwindled. Born 78 00:05:13.879 --> 00:05:17.319 prematurely and frequently ill in childhood, Keppler was a frail 79 00:05:17.360 --> 00:05:20.439 boy with weak vision. A bout of smallpox left his 80 00:05:20.480 --> 00:05:24.079 eyes damaged and his hands crippled, Yet he showed early 81 00:05:24.120 --> 00:05:27.319 intellectual gifts and in an almost mystical awe for the heavens. 82 00:05:28.279 --> 00:05:31.720 In fifteen seventy seven, at just six years old, Johannes's 83 00:05:31.759 --> 00:05:33.959 mother took him to a high place to witness the 84 00:05:34.000 --> 00:05:37.720 Great Comet of fifteen seventy seven, a spectacle that captivated 85 00:05:37.759 --> 00:05:41.959 astronomers across Europe. He later recalled being entranced by the 86 00:05:41.959 --> 00:05:45.639 bright comet hanging in the sky. Two years later, in 87 00:05:45.680 --> 00:05:48.439 fifteen eighty, he was called outside at night to see 88 00:05:48.480 --> 00:05:51.839 a lunar eclipse, noting how the moon appeared quite red, 89 00:05:52.240 --> 00:05:57.160 another formative experience for the young stargazer. These childhood events 90 00:05:57.360 --> 00:06:00.000 kindled a passion for astronomy that would last his entire 91 00:06:00.720 --> 00:06:02.920 even though his poor eyesight meant he would never be 92 00:06:03.000 --> 00:06:08.399 known from making telescopic discoveries like Alileo, Kepler himself joked 93 00:06:08.439 --> 00:06:11.680 that although his mind was sky bound, the shadow of 94 00:06:11.720 --> 00:06:15.319 his body lies here on earth, a poignant reflection he 95 00:06:15.360 --> 00:06:19.040 will later choose for his epitheph. Encouraged by his family's 96 00:06:19.079 --> 00:06:22.399 Lutheran faith and by his own evident intellect, Kepler pursued 97 00:06:22.439 --> 00:06:26.040 an education that combined classical learning with religious training. He 98 00:06:26.079 --> 00:06:29.279 attended local Latin schools, and in fifteen eighty four, at 99 00:06:29.360 --> 00:06:33.399 age thirteen, he entered the Protestant seminary at Eldenburg. He 100 00:06:33.519 --> 00:06:36.279 proved to be a brilliant student. By fifteen eighty nine, 101 00:06:36.399 --> 00:06:39.319 Kepler earned a scholarship to the University of Tubajin, a 102 00:06:39.399 --> 00:06:42.839 leading Protestant university, to study theology and prepare for the 103 00:06:42.920 --> 00:06:48.720 Lutheran ministry. At Tubingan's Tubingerstiff Seminary, Kepler received a thorough 104 00:06:48.720 --> 00:06:53.639 grounding in classical philosophy, mathematics, and astronomy. His mentor in 105 00:06:53.680 --> 00:06:56.759 mathematics and astronomy was Michael Maslin, one of the few 106 00:06:56.800 --> 00:07:00.399 academics of the time who embraced the Copernican heliocentric model, 107 00:07:00.759 --> 00:07:05.199 though cautiously and only in private lectures. Under Maslin's guidance, 108 00:07:05.319 --> 00:07:08.959 Kepler learned both the traditional Polemaic Earth centered system and 109 00:07:09.000 --> 00:07:14.519 the revolutionary Copernican Sun centered system of planetary motion. Kepler 110 00:07:14.600 --> 00:07:18.439 was quickly won over to Copernican's vision. He later wrote 111 00:07:18.480 --> 00:07:20.879 that it was a tubingin that he became a Copernican 112 00:07:21.160 --> 00:07:25.160 for what he called physical or if you prefer metaphysical reasons. 113 00:07:26.040 --> 00:07:29.000 In other words, he sensed that a sun centered cosmos 114 00:07:29.160 --> 00:07:33.120 had a deeper natural truth and harmony to it. Indeed, 115 00:07:33.199 --> 00:07:37.120 Kepler's faith in a rational God created order predisposed him 116 00:07:37.160 --> 00:07:40.120 to favor a system where the Sun, symbol of God's light, 117 00:07:40.480 --> 00:07:44.079 sat at the center. As a student, he even engaged 118 00:07:44.079 --> 00:07:48.040 in a public disputation defending heliocentrism on both scientific and 119 00:07:48.120 --> 00:07:51.800 theological grounds, arguing that the Sun is the principal source 120 00:07:51.839 --> 00:07:55.319 of motion to the universe. This was bold given that 121 00:07:55.439 --> 00:07:59.560 Lutheran and Catholic authorities alike still regarded heliocentrism with suspicion. 122 00:08:00.720 --> 00:08:05.160 Kepler's subtle deviations from strict Lutheran doctrine already began causing friction. 123 00:08:05.920 --> 00:08:08.879 He refused to fully subscribe to the formula of Concord 124 00:08:08.920 --> 00:08:12.399 in fifteen seventy seven, a Lutheran confession of faith, because 125 00:08:12.439 --> 00:08:16.240 he had private doubts on points of theology. Because of 126 00:08:16.279 --> 00:08:21.160 these scruples, Kepler's hopes of becoming a pastor dimmed. Nevertheless, 127 00:08:21.360 --> 00:08:24.600 he saw no conflict between faith and science. I wanted 128 00:08:24.600 --> 00:08:27.600 to become a theologian. For a long time. I was unhappy. 129 00:08:28.079 --> 00:08:31.279 Now behold, God is praised by my work, even in astronomy. 130 00:08:31.519 --> 00:08:35.759 Kepler later reflected to him uncovering the mathematical laws of 131 00:08:35.799 --> 00:08:39.440 creation was a form of devotion. This conviction set the 132 00:08:39.480 --> 00:08:44.559 stage for his life's work. In fifteen ninety four, at 133 00:08:44.559 --> 00:08:47.639 the age of twenty two, Johannes Kepler left academia to 134 00:08:47.679 --> 00:08:51.639 begin a career in teaching and incidentally, in government service 135 00:08:51.639 --> 00:08:55.120 as an astrologer. He was recommended for and accepted a 136 00:08:55.159 --> 00:08:58.919 post as professor of mathematics at the Protestant Seminary in 137 00:08:59.000 --> 00:09:02.960 Gratz in the US Austrian province of Steria. In this role, 138 00:09:03.000 --> 00:09:06.399 he taught arithmetic, geometry, and sometimes Greek and rhetoric to 139 00:09:06.399 --> 00:09:10.919 the school students. He also carried the title of district mathematician, 140 00:09:11.159 --> 00:09:14.039 which meant he was responsible for issuing official calendars in 141 00:09:14.159 --> 00:09:18.279 astrological almanacs, a lucrative and respected task at the time. 142 00:09:19.159 --> 00:09:22.360 In the late sixteenth century, there was no firm separation 143 00:09:22.440 --> 00:09:26.440 between astronomy and astrology. The two were considered two sides 144 00:09:26.480 --> 00:09:30.559 of the same coin. Like other learned astronomers, even Tycho 145 00:09:30.600 --> 00:09:34.480 Brahe and Galileo, Kepler practiced astrology to earn his keep. 146 00:09:35.320 --> 00:09:38.240 He cast horoscopes for wealthy patrons and local nobility, and 147 00:09:38.279 --> 00:09:42.919 made weather and political predictions in annual calendars. Though he 148 00:09:43.000 --> 00:09:47.799 privately disdained the more superstitious aspects of astrology, he conceded 149 00:09:47.840 --> 00:09:51.480 that mother astronomy would surely have to suffer hunger if 150 00:09:51.519 --> 00:09:55.159 the daughter astrology did not earn their bread. In other words, 151 00:09:55.159 --> 00:09:57.799 it was astrology that paid the bills, allowing him to 152 00:09:57.799 --> 00:10:01.600 pursue pure astronomy. Kepler spent a huge amount of time 153 00:10:01.679 --> 00:10:05.440 trying to reform astrology on a sounder footing, composing over 154 00:10:05.480 --> 00:10:09.159 eight hundred horoscopes and several treaties on the subject. He 155 00:10:09.200 --> 00:10:13.279 aimed to distill whatever he thought scientifically plausible, for instance, 156 00:10:13.440 --> 00:10:17.080 effects of the sun, moon, and planets mediated through an 157 00:10:17.120 --> 00:10:21.120 Earth's soul via harmonies or light from what he called 158 00:10:21.320 --> 00:10:25.759 the Swinnish rashness of fortune tellers. In sixteen oh one, 159 00:10:25.879 --> 00:10:29.200 he even wrote a short work on giving astrology sounder 160 00:10:29.200 --> 00:10:33.559 foundations to accompany one of his almanacs, and in sixteen ten, 161 00:10:34.039 --> 00:10:38.120 when two other authors feuded over astrology merits, Kepler intervened 162 00:10:38.159 --> 00:10:43.080 with attract third party intervening, cautioning that while much astrological 163 00:10:43.120 --> 00:10:47.159 superstition deserves rejection, one must not throw the baby out 164 00:10:47.200 --> 00:10:51.440 with the bath water by dismissing real cosmic influences. This 165 00:10:51.600 --> 00:10:55.799 balanced approach typified Kepler's unque blend of mysticism and empiricism 166 00:10:55.919 --> 00:11:00.000 during his grazzias. Even while he fulfilled his public duties, 167 00:11:00.480 --> 00:11:04.519 Kepler was pursuing an arditious private research program, an attempt 168 00:11:04.600 --> 00:11:08.639 to decipher the geometrical plan of the cosmos. Shortly after 169 00:11:08.759 --> 00:11:11.399 arriving at Grotz, he experienced what he described as a 170 00:11:11.399 --> 00:11:16.080 moment of illumination. On July nineteenth, fifteen ninety five, while 171 00:11:16.120 --> 00:11:19.720 teaching a class, Kepler was explaining the periodic conjunctions of 172 00:11:19.799 --> 00:11:23.360 Saturn and Jupiter and the Zodiac when he had an epiphany. 173 00:11:24.120 --> 00:11:27.080 He realized that the intervals between planets might be explained 174 00:11:27.120 --> 00:11:32.480 by pure geometry. Initially, Kepler tried inscribing and circumscribing one 175 00:11:32.480 --> 00:11:37.320 circle between another using regular polygons, seeking a unique geometric 176 00:11:37.360 --> 00:11:40.519 spacing for the six known planets, but this approach failed 177 00:11:40.519 --> 00:11:45.960 to much observations. He then contemplated three dimensional shapes. In 178 00:11:46.000 --> 00:11:50.519 a breakthrough, Kepler imagined nesting the five periodic platonic solids 179 00:11:51.000 --> 00:11:55.279 one inside another, each separated by circumscribed and inscribed sphere. 180 00:11:56.399 --> 00:11:59.320 There were only five such polyhedra, and placing them in 181 00:11:59.320 --> 00:12:02.399 the proper order produced six layers, which he identified with 182 00:12:02.440 --> 00:12:09.399 the six planets Mercury, Venus, Earth, Mars, Jupiter, Saturn. To 183 00:12:09.440 --> 00:12:12.799 Kepler's delight, the model roughly matched the relative sizes of 184 00:12:12.799 --> 00:12:16.480 the planet's orbits as known from Copernicus's data, Especially for 185 00:12:16.600 --> 00:12:20.360 planets beyond Mercury. He believed he had glimpsed the very 186 00:12:20.440 --> 00:12:25.919 geometric blueprint of God. Geometry is co eternal with God, 187 00:12:26.200 --> 00:12:29.039 and God used it in laying out the world Keppelo 188 00:12:29.080 --> 00:12:33.240 would write later reflecting his neoplatonic conviction that geometrical forms 189 00:12:33.480 --> 00:12:37.960 give structure to creation. With almost evangelical zeal, the young 190 00:12:38.000 --> 00:12:42.519 astronomer set out to share his revelation. In fifteen ninety six, 191 00:12:42.559 --> 00:12:46.200 at just twenty five years old, Keppela published his first book, 192 00:12:46.919 --> 00:12:53.879 Pisterium Cosmographicum Mystery of the Cosmos. This was his first 193 00:12:53.919 --> 00:12:57.080 bold attempt to decipher the divine geometric plan of the universe. 194 00:12:58.000 --> 00:13:00.639 Kepplo was a deeply religious thinker who believe that God, 195 00:13:00.919 --> 00:13:04.600 the great mathematician, had built the cosmos with mathematical harmony. 196 00:13:05.879 --> 00:13:09.360 Inspired by quasi mystical revelation while teaching in Gods, he 197 00:13:09.440 --> 00:13:12.279 became convinced that the spacing of the six known planets 198 00:13:12.639 --> 00:13:15.960 was no accident. It must be patterned after the five 199 00:13:16.000 --> 00:13:20.879 perfect platonic solids of antiquity. Kepler set out to prove 200 00:13:20.919 --> 00:13:24.279 that each planetary orbit is separated by a nested polyhedron, 201 00:13:24.840 --> 00:13:28.519 inscribed and circumscribed by spheres matching the orbit of one 202 00:13:28.519 --> 00:13:32.360 planet to the next. This elegant model, he thought, explained 203 00:13:32.360 --> 00:13:35.039 why there were exactly six planets and provided a compelling 204 00:13:35.080 --> 00:13:41.200 geometric rationale for Copernicus's son's censored system. Keppler's Mysterium was 205 00:13:41.240 --> 00:13:45.679 the first published defense of copernicant heliocentrism since Copernicus himself, 206 00:13:46.120 --> 00:13:49.279 and it was strikingly unusual for the blending rigorous astronomy 207 00:13:49.440 --> 00:13:54.120 with neoplatonic mysticism. In the book's preface, he declared his 208 00:13:54.200 --> 00:13:57.039 mission to show that God, in creating the universe and 209 00:13:57.080 --> 00:13:59.720 regulating the order of the cosmos, had in view the 210 00:13:59.759 --> 00:14:04.240 fire irregular bodies of geometry, and that he has fixed, 211 00:14:04.360 --> 00:14:07.879 according to those geometric dimensions, the number of the heavens, 212 00:14:08.120 --> 00:14:13.200 their proportions, and relations of their movements. The Mysterium did 213 00:14:13.200 --> 00:14:16.759 more than propose a poetic model. It insisted that astronomy 214 00:14:16.840 --> 00:14:20.279 must explain the actual spacing of planetary orbits in three 215 00:14:20.320 --> 00:14:26.360 dimensional space, not just their abstract order. To Kepler, Copernicus's 216 00:14:26.399 --> 00:14:29.000 system implied a physical reality in which nothing could be 217 00:14:29.120 --> 00:14:33.559 altered without upsetting the harmony of the whole. This mindset 218 00:14:33.639 --> 00:14:36.120 led him to consider the Sun's force as it caused 219 00:14:36.120 --> 00:14:40.200 a planetary motion weakening with distance, oppressing, and insight that 220 00:14:40.279 --> 00:14:45.600 nudged astronomy away from purely kinematic models towards physics. Although 221 00:14:45.600 --> 00:14:49.440 the platonic solid model itself was not quantitatively accurate, its 222 00:14:49.480 --> 00:14:52.879 beauty and haunting strangeness captivated Kepler and set him on 223 00:14:52.919 --> 00:14:56.919 a path of asking deeper questions. He even published a 224 00:14:56.960 --> 00:15:00.039 second edition twenty five years later, unwilling to aband and 225 00:15:00.120 --> 00:15:03.600 in the idea that some fundamental harmonies underlies the cosmos. 226 00:15:05.720 --> 00:15:09.759 With hindsight, we see Mysterium Cosmographicum as an important stepping 227 00:15:09.799 --> 00:15:15.080 stone and empirically inaccurate but esthetically beautiful hypothesis that nevertheless 228 00:15:15.120 --> 00:15:19.080 prompted Kepler to seek physical causes and would ultimately lead 229 00:15:19.080 --> 00:15:24.200 to his monumental Laws of planetary motion. While in Grotz, 230 00:15:24.279 --> 00:15:27.879 Kepler also began side studies in chronology and astrology, even 231 00:15:27.919 --> 00:15:30.960 trying to link planetary positions to weather and earthly events. 232 00:15:32.039 --> 00:15:34.720 He speculated about the Earth having a soul that responds 233 00:15:34.720 --> 00:15:37.559 to the positions of the planets. This was part of 234 00:15:37.600 --> 00:15:39.559 a grand plan that he had sketched out to write 235 00:15:39.600 --> 00:15:43.279 several books on the stationary sun and fixed stars, on 236 00:15:43.360 --> 00:15:47.000 planetary motions, on the physical nature of planets, and on 237 00:15:47.039 --> 00:15:50.960 the influences of the heavens on Earth. The Mysterium was 238 00:15:51.039 --> 00:15:55.639 only the first installment of this ambitious program. However, events 239 00:15:55.639 --> 00:15:58.240 in Grots would soon disrupt Kepler's work and force him 240 00:15:58.240 --> 00:16:02.960 to flee. Our Reformation was gathering steam under Archduke Shun 241 00:16:03.000 --> 00:16:06.440 Emperor Ferdinand the second, a staunch Catholic, determined to root 242 00:16:06.480 --> 00:16:11.559 out Protestantism in his realms. Tensions in Steria mounted in 243 00:16:11.600 --> 00:16:15.000 September fifteen ninety eight, and decree expelled all Protestant teachers 244 00:16:15.000 --> 00:16:19.320 and preachers from Gratz. Initially, Keppel was exempted from expulsion 245 00:16:19.320 --> 00:16:23.639 because of his valuable status as district mathematician. The authorities 246 00:16:23.679 --> 00:16:26.879 did not want to lose the calendar maker, but Kepler 247 00:16:27.000 --> 00:16:29.759 felt far from safe. That year, he wrote to a 248 00:16:29.759 --> 00:16:33.039 friend that he foresore dark times ahead. Sure enough, by 249 00:16:33.039 --> 00:16:38.480 fifteen ninety nine his position was untenable. Meanwhile, in Prague, 250 00:16:38.639 --> 00:16:42.399 Tycho brahe had been appointed Imperial mathematician to Emperor Rudolph 251 00:16:42.440 --> 00:16:46.399 the second. Ticho, the Great Danish astronomer, was eager for 252 00:16:46.480 --> 00:16:48.679 a skilled assistant to help make sense of his vast 253 00:16:48.679 --> 00:16:53.399 treasury of planetary observations. He had heard of Kepler's talent 254 00:16:53.440 --> 00:16:57.879 for theoretical insight. In December fifteen ninety nine, Tycho intended 255 00:16:57.919 --> 00:17:01.200 an invitation to Kepler to join him in Prague. Kepler 256 00:17:01.320 --> 00:17:04.720 leapt at the opportunity, without even waiting for the formal 257 00:17:04.799 --> 00:17:07.839 letter to arrive. He set off from Gratz on January first, 258 00:17:07.960 --> 00:17:11.359 sixteen hundred, heading north to Bohemia in hopes that Tycho's 259 00:17:11.359 --> 00:17:15.079 patronage could solve both his scientific quandaries and his precarious 260 00:17:15.079 --> 00:17:20.759 political situation. Kepler's departure from Grotz was abrupt. He left 261 00:17:20.799 --> 00:17:23.440 behind his post and the home that he had established there, 262 00:17:23.839 --> 00:17:26.039 and it must be noted he left in the company 263 00:17:26.079 --> 00:17:30.240 of some emotional turmoil. During his Grotz years, Keppler had 264 00:17:30.279 --> 00:17:33.440 fallen in love and married. In December fifteen ninety five, 265 00:17:33.680 --> 00:17:36.559 he met Barbara Muller, a twenty three year old, twice 266 00:17:36.599 --> 00:17:40.359 widowed young woman with a small daughter. Barbara came from 267 00:17:40.359 --> 00:17:43.680 a prosperous family, for Falla was a successful mill owner, 268 00:17:44.119 --> 00:17:48.400 whereas Keppler was an impecuineous scholar. Her Falla was initially 269 00:17:48.400 --> 00:17:52.240 opposed to the match, considering Kepler's poverty unacceptable despite his 270 00:17:52.319 --> 00:17:58.000 noble ancestry. Only after Kepler finished Mysterium Cosmographicum, perhaps proving 271 00:17:58.039 --> 00:18:01.640 his potential, did her family rely, and Barbara and Johannes 272 00:18:01.680 --> 00:18:06.160 married on April twenty seventh, fifteen ninety seven. The marriage 273 00:18:06.200 --> 00:18:09.200 in its early years was reportedly strained by financial worries 274 00:18:09.279 --> 00:18:12.880 and by Kepler's single minded focus on his studies. They 275 00:18:12.920 --> 00:18:15.279 had two children in Grotz in fifteen ninety eight and 276 00:18:15.319 --> 00:18:19.039 fifteen ninety nine, but tragically both infants, a son, Heinrich 277 00:18:19.160 --> 00:18:23.000 and a daughter, Susannah, died in infancy. It was amid 278 00:18:23.039 --> 00:18:27.920 these personal trials that Kepler abandoned Grotz. By September sixteen hundred, 279 00:18:27.960 --> 00:18:30.880 after a final edict demanded that all Protestants convert to 280 00:18:30.880 --> 00:18:35.200 Catholicism or leave Steria. Kepler and Barbara, pregnant again, packed 281 00:18:35.240 --> 00:18:39.519 their belongings and fled grots for Prague, effectively as religious refugees. 282 00:18:40.720 --> 00:18:42.799 Keppeler did not know it yet, but he would never 283 00:18:42.839 --> 00:18:46.240 return into the life of a provincial school teacher, ahead 284 00:18:46.279 --> 00:18:49.799 lay his most productive scientific years under the patronage of 285 00:18:49.839 --> 00:18:54.440 the Holy Roman Emperor. When Keppeler arrived in Prague in 286 00:18:54.480 --> 00:18:57.400 early sixteen hundred, he entered an environment that must have 287 00:18:57.440 --> 00:18:59.960 seemed like the Promised Land to a man obsessed with astronomy. 288 00:19:01.480 --> 00:19:04.960 Tycho Brahe welcomed him to the Imperial Observatory and soon 289 00:19:05.000 --> 00:19:09.160 put Keplar to work analyzing observations of Mars. Mars was 290 00:19:09.200 --> 00:19:13.519 famously the most troublesome planet for astronomers. Its apparent backward 291 00:19:13.559 --> 00:19:17.599 retrograde motions and changes in brightness had defied simple explanation 292 00:19:17.759 --> 00:19:22.319 in circular orbit models. Tycho possessed the most precise Mars 293 00:19:22.400 --> 00:19:27.519 data ever obtained, measured without telescopes using giant citing instruments. 294 00:19:27.799 --> 00:19:30.440 His measurements were accurate within a arc minute or two. 295 00:19:31.720 --> 00:19:35.240 For the first time, Kepler had the accurate empirical foundation 296 00:19:35.359 --> 00:19:39.359 he needed. However, Tycho was protective of his data. He 297 00:19:39.440 --> 00:19:42.839 did not initially allow Kepler unlimited access or copies of 298 00:19:42.839 --> 00:19:46.839 his observations. Kepler estimated it might take him up to 299 00:19:46.920 --> 00:19:49.599 two years of hard work to test his geometric theories 300 00:19:49.759 --> 00:19:52.960 against Tycho's Mars data, since he would have to perform 301 00:19:53.039 --> 00:19:57.279 calculations on site. He and Tycho had a brief falling 302 00:19:57.359 --> 00:19:59.839 out in the spring of sixteen hundred over for more 303 00:20:00.000 --> 00:20:02.759 employment terms and salary that led Kepler to leave for 304 00:20:02.799 --> 00:20:07.480 a short time. Fortunately, the reconciled quickly and reached an agreement. 305 00:20:08.119 --> 00:20:11.000 Tycho recognized Keppler's value and secured him a position as 306 00:20:11.039 --> 00:20:15.880 an imperial collaborator. By summer of sixteen hundred, after returning 307 00:20:15.920 --> 00:20:18.720 to Gratz briefly to collect his family, Kepler settled in 308 00:20:18.759 --> 00:20:23.839 Prague for good. Tragically, Kepler's direct collaboration with the illustrious 309 00:20:23.920 --> 00:20:28.200 Tycho would be short lived. In October sixteen oh one, 310 00:20:28.440 --> 00:20:32.680 only about a year after Kepler arrived, Tycho Brahe died suddenly. 311 00:20:33.759 --> 00:20:37.200 Tycho's death threatened to leave Kepler stranded, but the Emperor 312 00:20:37.240 --> 00:20:42.039 Rudolph the Second promptly appointed Kepler as Tycho's successor Imperial Mathematician. 313 00:20:43.200 --> 00:20:46.440 This was the most prestigious post for a mathematician in Europe, 314 00:20:46.839 --> 00:20:50.759 essentially making Kepler the court astronomer. It also gave him 315 00:20:50.759 --> 00:20:55.759 custody of Tycho's precious astronomical data. After some wrangling with 316 00:20:55.799 --> 00:20:58.920 Tycho's heirs, who tried to claim that data was private property, 317 00:20:59.279 --> 00:21:02.880 Kepler gained access to the observations he needed. He was 318 00:21:02.960 --> 00:21:06.480 keenly aware of the importance of this moment. He had 319 00:21:06.599 --> 00:21:11.160 in his hands the raw material to revolutionize astronomy, to 320 00:21:11.400 --> 00:21:15.119 us on whom divine benevolence has bestowed the most diligent 321 00:21:15.160 --> 00:21:20.200 of observers, Tycho Brahe, from whose observations this eight minute 322 00:21:20.319 --> 00:21:23.400 error in the orbit of Mars is deduced. It is 323 00:21:23.440 --> 00:21:26.240 fitting that we accept with grateful minds this gift from 324 00:21:26.279 --> 00:21:29.559 God and both acknowledge and build upon it. Referring to 325 00:21:29.640 --> 00:21:32.680 a tiny discrepancy Tycho had found in Mars's orbit that 326 00:21:32.799 --> 00:21:36.599 hinted the ancient models were wrong, Kepla would indeed build 327 00:21:36.680 --> 00:21:39.559 upon Tycho's legacy, and in doing so he changed our 328 00:21:39.640 --> 00:21:44.759 view of the cosmos. As imperial mathematician and Prague, Keppler's 329 00:21:44.839 --> 00:21:49.400 duties were twofold, for example, providing astrological forecasts and calendars 330 00:21:49.400 --> 00:21:52.920 to the Emperor, and to conduct astronomical research, including the 331 00:21:52.960 --> 00:21:56.359 completion of the new Rudolphine Tables, an updated set of 332 00:21:56.400 --> 00:22:01.839 astronomical tables, planetary positions, star catalogs, et cetera, using tycho 333 00:22:01.920 --> 00:22:06.160 superior observations and per Rudolph the second was an enlightened 334 00:22:06.160 --> 00:22:10.000 and eccentric patron of the sciences, interested in astronomy, alchemy, 335 00:22:10.079 --> 00:22:14.480 and all matter of esoteric knowledge. He tolerated Keppler's Lutheran faith, 336 00:22:14.559 --> 00:22:19.240 despite Prague being officially Catholic. In practice, Kepler had a 337 00:22:19.240 --> 00:22:22.960 fair degree of intellectual freedom at Ruolph's court, even as 338 00:22:22.960 --> 00:22:26.079 he struggled with intermittent salary payments from the cash strapped 339 00:22:26.119 --> 00:22:30.559 Imperial Treasury. It was an invigorating situation. Kepler rubbed shoulders 340 00:22:30.559 --> 00:22:34.480 with other learned men in Prague from Jeweler's turned mathematicians 341 00:22:34.519 --> 00:22:38.319 like Josh Bergee, tou scalars like Johannes Mathaus, Whacker and 342 00:22:38.440 --> 00:22:42.759 David Fabricius. This collegial atmosphere, combined with Keppler's own single 343 00:22:42.799 --> 00:22:47.319 minded determination, led to an explosion of productivity. The eleven 344 00:22:47.400 --> 00:22:50.200 years Kepler spent in Prague sixteen oh one to sixteen 345 00:22:50.240 --> 00:22:53.680 twelve would be the most scientifically fruitful time of his life. 346 00:22:55.720 --> 00:22:58.079 One of Kepler's first targets of study was the orbit 347 00:22:58.119 --> 00:23:01.759 of Mars. Continuing the work Tycho had assigned him, Kepeler 348 00:23:01.759 --> 00:23:04.599 approached the problem with a novel mindset. He was willing 349 00:23:04.640 --> 00:23:07.880 to abandon the ancient insumption that planetary motions must be 350 00:23:07.960 --> 00:23:12.359 combinations of uniform circular paths. Instead, he sought a single, 351 00:23:12.519 --> 00:23:15.880 unified orbit from Mars, shaped by a physical cause, what 352 00:23:15.960 --> 00:23:20.319 he called a celestial physics. He suspected the Sun was 353 00:23:20.359 --> 00:23:22.599 the source of a force that drove the planets, an 354 00:23:22.599 --> 00:23:25.880 idea inspired by his belief that the son symbolized God 355 00:23:25.920 --> 00:23:29.599 the Father, and likely influenced by William Gilbert's sixteen hundred 356 00:23:29.599 --> 00:23:34.000 book d Magneti, which posited a magnetic soul in the Earth. 357 00:23:35.039 --> 00:23:38.079 Keppler theorized that a force emanating from the Sun weakened 358 00:23:38.119 --> 00:23:41.759 with distance, causing planets further out to move more slowly, 359 00:23:42.160 --> 00:23:45.880 a remarkable prescient intuition we can recognize in it an 360 00:23:45.960 --> 00:23:49.920 early notion of a gravitational or magnetic inverse square law. 361 00:23:51.319 --> 00:23:54.440 Armed with Tycho's precise measurements of Mars positions at various 362 00:23:54.440 --> 00:23:58.319 points in its orbits, Kepler attacked the data with tireless calculations. 363 00:23:59.359 --> 00:24:02.880 He tried one geometric model after another, measuring the error 364 00:24:02.960 --> 00:24:06.359 each time. Initially, he attempted to use a small oval 365 00:24:06.480 --> 00:24:10.039 like path, and even tried incorporating the old equon a 366 00:24:10.039 --> 00:24:13.599 mathematical point that Copernicus had eliminated to see if he 367 00:24:13.599 --> 00:24:17.039 could fit the data, but nothing gave a perfect match. 368 00:24:17.680 --> 00:24:21.119 Mars observed positions differed by as much as eight arc 369 00:24:21.200 --> 00:24:24.640 minutes eight sixtieth of a degree from the best circular 370 00:24:24.720 --> 00:24:28.319 or oval models Kepler could construct. Instead of dismissing this 371 00:24:28.440 --> 00:24:33.400 tiny discrepancy, Kepler famously said that the commander of eight minutes. 372 00:24:34.079 --> 00:24:37.720 It the error will lead us to complete reform of astronomy. 373 00:24:38.880 --> 00:24:41.880 His contemporaries might have swept such a small error under 374 00:24:41.880 --> 00:24:46.000 the rug, but Kepler trusted the data with Tycho's observations. 375 00:24:46.319 --> 00:24:49.559 This eight minute discrepancy is a gift of God, he wrote, 376 00:24:49.759 --> 00:24:53.000 believing that such anomalies were clues to the true theory. 377 00:24:54.359 --> 00:24:58.559 After numerous failed attempts, Kepler made his greatest discovery in 378 00:24:58.680 --> 00:25:01.160 late sixteen o four. Hed had what one might call 379 00:25:01.240 --> 00:25:04.880 his second epiphany, the first being the platonic solids model. 380 00:25:05.640 --> 00:25:09.279 Having tried over forty different geometrical constructions to fit Mars's orbit, 381 00:25:09.559 --> 00:25:12.119 he finally considered that the path might be an ellipse 382 00:25:12.559 --> 00:25:16.960 rather than a circle or arbitrary oval. The ellipses were 383 00:25:17.000 --> 00:25:20.519 a simple conic section, a familiar shape, Yet no astronomer 384 00:25:20.559 --> 00:25:23.920 before had dad suggests the planets literally travel on ellipses. 385 00:25:25.240 --> 00:25:28.519 Kepler had initially thought an ellipse was too simple. Surely, 386 00:25:28.799 --> 00:25:31.319 he imagined the great minds of antiquity would have tried 387 00:25:31.359 --> 00:25:34.640 it if it worked. But when he plotted Mars's position 388 00:25:34.720 --> 00:25:37.559 as an elliptical path with the Sun at once focus 389 00:25:37.599 --> 00:25:41.559 of the ellipse, the data fit beautifully, the long standing 390 00:25:41.599 --> 00:25:45.240 mystery of Mars's motion was solved. Mars, and by extension, 391 00:25:45.279 --> 00:25:48.559 the other planets move around the Sun in ellipses rather 392 00:25:48.599 --> 00:25:53.559 than perfect circles. Kepler immediately generalized this insight into what 393 00:25:53.599 --> 00:25:57.640 we now call Kepler's first law, the orbits of the 394 00:25:57.680 --> 00:26:02.480 planets or ellipses with the Sun at one time focus. Furthermore, 395 00:26:02.599 --> 00:26:05.039 he had already deduced a rule for how a planet 396 00:26:05.119 --> 00:26:09.559 speed varies along its orbit. By sixteen oh two. Through 397 00:26:09.640 --> 00:26:13.240 laborious calculations, Kepler found that the line connecting a planet 398 00:26:13.279 --> 00:26:16.680 to the Sun sweeps out equal areas in equal times, 399 00:26:17.000 --> 00:26:19.519 implying that a planet moves faster when nearer the Sun 400 00:26:19.759 --> 00:26:23.200 and slower when farther. This became Kepler's second law of 401 00:26:23.240 --> 00:26:27.680