科学技术史课件：第九讲-1：理解天体和地上物体的.ppt

1、第十章：理解天体-地物的运动 在所有这些行星中间，太阳傲然 坐镇。在这个最美丽的庙堂中，我们难道还能把这发光体放到更恰当的别的什么位置使它同时普照全体吗?人们正确地把太阳称为“巨灯”、“理智”、“宇宙之王”，太阳就这样高踞王位之上，统治着围绕膝下的子女一样的众行星。 -哥白尼：天体运行论第1卷Copernicus systemCopernicus, the great astronomer重新安排宇宙重新安排宇宙 哥白尼(1473-1543)于1496 年到意大利，成波伦亚大学天 文学教授诺瓦腊(1454-1503) 的学生。这是航海时刻，在 海上确定船只位置和编写航 海历书使天文学受到新刺激

2、。当时在学术上占主导地位的托勒密体系结构复杂，困难重重。诺瓦腊批评托勒密地心宇宙模型数学上太不合理，给哥白尼以深刻影响。哥白尼在意大利读了他能够找到的所有古代哲学著作，并和老师进行了天文观测。 哥白尼受毕达哥拉斯学派影响，把数学上是否简单完美作为评价一个学说的标准，托勒密体系不符合这个标准，所以他想探新路。 在意大利游学10年后，哥白尼返回波兰，边行医，边担负着教会工作，边开始构思和撰写天体运行论。 1543年，当作者老卧病榻时，这本写作、修改和保存了36年的书终于出版。哥白尼见到己著后与世长辞，但这本书却引起一场巨大、持久、深刻的学术思想革命，使人类开始重新认识宇宙、地球、物体的运动乃至人类

3、自身在宇宙中的位置。 哥白尼使古希腊人和中世哥白尼使古希腊人和中世纪阿拉伯学者关于地球绕纪阿拉伯学者关于地球绕己轴自转思想和阿利斯塔己轴自转思想和阿利斯塔克关于地球绕太阳公转主克关于地球绕太阳公转主张以新形式复活。张以新形式复活。 哥白尼体系数学形式极简哥白尼体系数学形式极简单，第一次正确描述了水、单，第一次正确描述了水、金、地和月、火、土、木金、地和月、火、土、木星轨道实际相对太阳的顺星轨道实际相对太阳的顺序位置，指出它们的轨道序位置，指出它们的轨道大致在一个平面上，公转大致在一个平面上，公转方向也一致，月是地卫星，方向也一致，月是地卫星，和地一起绕日旋转。和地一起绕日旋转。 这学说成了现代

4、天文学和这学说成了现代天文学和天体力学的真正出发点。天体力学的真正出发点。 哥白尼在世时对自己理论的命运并 不乐观，他坚持研究却迟迟不发表 研究成果。 他当时遭到两方面的压力他当时遭到两方面的压力: 第一，地上人据日常经验观察天体运动时，更易接受地心说。若地在公转和自转，地上物何以不分裂飞散?这问题哥白尼未能解答(这一令人困惑的问题，使伽利略和牛顿等人通过思考和研究推进了哥白尼的事业)。 第二，哥白尼学说触及当时人心中一个神圣而敏感的问题：无论罗马教会还是刚产生的路德和加尔文新教，都认为世界是为人的安适和利益创造的，人受到上帝的特殊恩宠，人居住的星体自然是宇宙中心。让人从宇宙中心挪到一自转并绕

5、日旋转的星球上是不可思议的。Nicolas Copernicus(1473-1543) Copernicus is said to be the founder of modern astronomy. He was born in Poland,1 and eventually was sent off to Cracow University, there to study mathematics and optics; at Bologna, canon law. Returning from his studies in Italy, Copernicus, through the i

6、nfluence of his uncle, was appointed as a canon in the cathedral of Frauenburg where he spent a sheltered and academic life for the rest of his days. Because of his clerical position, Copernicus moved in the highest circles of power; but a student he remained. For relaxation Copernicus painted and t

7、ranslated Greek poetry into Latin. His interest in astronomy gradually grew to be one in which he had a primary interest. His investigations were carried on quietly and alone, without help or consultation. He made his celestial observations from a turret situated on the protective wall around the ca

8、thedral, observations were made bare eyeball, so to speak, as a hundred more years were to pass before the invention of the telescope. In 1530, Copernicus completed and gave to the world his great work De Revolutionibus, which asserted that the earth rotated on its axis once daily and traveled aroun

9、d the sun once yearly: a fantastic concept for the times. Up to the time of Copernicus the thinkers of the western world believed in the Ptolemiac theory that the universe was a closed space bounded by a spherical envelope beyond which there was nothing. Claudius Ptolemy, an Egyptian living in Alexa

10、ndria, at about 150 A.D., gathered and organized the thoughts of the earlier thinkers. (It is to be noted that one of the ancient Greek astronomers, Aristarchus, did have ideas similar to those more fully developed by Copernicus but they were rejected in favour of the geocentric or earth-centered sc

11、heme as was espoused by Aristotle.) Ptolemys findings were that the earth was a fixed, inert, immovable mass, located at the center of the universe, and all celestial bodies, including the sun and the fixed stars, revolved around it. It was a theory that appealed to human nature. It fit with the cas

12、ual observations that a person might want to make in the field; and second, it fed mans ego. Copernicus was in no hurry to publish his theory, though parts of his work were circulated among a few of the astronomers that were giving the matter some thought; indeed, Copernicus work might not have ever

13、 reached the printing press if it had not been for a young man who sought out the master in 1539. George Rheticus was a 25 year old German mathematics professor who was attracted to the 66 year old cleric, having read one of his papers. Intending to spend a few weeks with Copernicus, Rheticus ended

14、up staying as a house guest for two years, so fascinated was he with Copernicus and his theories. Now, up to this time, Copernicus was reluctant to publish, - not so much that he was concerned with what the church might say about his novel theory (De Revolutionibus was placed on the Index in 1616 an

15、d only removed in 1835), but rather because he was a perfectionist and he never thought, even after working on it for thirty years, that his complete work was ready, - there were, as far as Copernicus was concerned, observations to be checked and rechecked. (Interestingly, Copernicus original manusc

16、ript, lost to the world for 300 years, was located in Prague in the middle of the 19th century; it shows Copernicus pen was, it would appear, continually in motion with revision after revision; all in Latin as was the vogue for scholarly writings in those days.) Copernicus died in 1543 and was never

17、 to know what a stir his work had caused. It went against the philosophical and religious beliefs that had been held during the medieval times. Man, it was believed (and still believed by some) was made by God in His image, man was the next thing to God, and, as such, superior, especially in his bes

18、t part, his soul, to all creatures, indeed this part was not even part of the natural world (a philosophy which has proved disastrous to the earths environment as any casual observer of the 20th century might confirm by simply looking about). Copernicus theories might well lead men to think that the

19、y are simply part of nature and not superior to it and that ran counter to the theories of the politically powerful churchmen of the time. Two other Italian scientists of the time, Galileo and Bruno, embraced the Copernican theory unreservedly and as a result suffered much personal injury at the han

20、ds of the powerful church inquisitors. Giordano Bruno had the audacity to even go beyond Copernicus, and, dared to suggest, that space was boundless and that the sun was and its planets were but one of any number of similar systems: Why! - there even might be other inhabited worlds with rational bei

21、ngs equal or possibly superior to ourselves. For such blasphemy, Bruno was tried before the Inquisition, condemned and burned at the stake in 1600. Galileo was brought forward in 1633, and, there, in front of his betters, he was, under the threat of torture and death, forced to his knees to renounce

22、 all belief in Copernican theories, and was thereafter sentenced to imprisonment for the remainder of his days. The most important aspect of Copernicus work is that it forever changed the place of man in the cosmos; no longer could man legitimately think his significance greater than his fellow crea

23、tures; with Copernicus work, man could now take his place among that which exists all about him, and not of necessity take that premier position which had been assigned immodestly to him by the theologians. Of all discoveries and opinions, none may have exerted a greater effect on the human spirit t

24、han the doctrine of Copernicus. The world had scarcely become known as round and complete in itself when it was asked to waive the tremendous privilege of being the center of the universe. Never, perhaps, was a greater demand made on mankind - for by this admission so many things vanished in mist an

25、d smoke! What became of our Eden, our world of innocence, piety and poetry; the testimony of the senses; the conviction of a poetic - religious faith? No wonder his contemporaries did not wish to let all this go and offered every possible resistance to a doctrine which in its converts authorized and

26、 demanded a freedom of view and greatness of thought so far unknown, indeed not even dreamed of. Goethe. 傅科摆证明地球自转 事实上，直到1851年法国 人傅科发明摆，才证明了地球的自转。这摆被吊起，可经久不停地摆动，摆下有一刻度盘，由于地球的自转，盘随地球旋转， 因而可见摆平面相对 刻度盘不断改变方位。不同纬度的摆动 如果把傅科摆放置赤道上呢？那样的话， 我们将观察不到任 何转动。把摆锤的运 动看做一维谐振（单摆），由于它的运 动方 向与地轴平行，而地轴相对遥远的 恒星是静止的，所以我们观

27、测 不到傅科 摆相对地面的转动。 现在把傅科摆移回巴黎。摆锤的运动可以分解为沿地轴方向 的和与之垂直方向上的两个分运动。后者会产生相对地面的旋转 （正如北极的傅科摆）。这两个分运动合成的结果是，从地面上 的人看来，傅科摆以某种角速度缓慢的旋转介于傅科摆在北 极和赤道的角速度之间。（也可以从科里奥利力的角度解释，得 出的结论是一样的）如果在北极的观测到傅科摆旋转一周的时间 是A（A=24h），那么在任意纬度上，傅科摆旋转一周所需的时 间是A/sin。对于巴黎，这个数字是31.8小时。 An artists image of the moving Earth. Image courtesy of

28、Corel Corporation. The Heliocentric System 另外，哥白尼描述的行星运动是匀速的，轨道是圆形，这就使他不得不借托勒密的轮子来解释行星的实际运动。他的体系还需新的伟大发现才能立足。The Copernican Universe殉道者布鲁诺Giordano Bruno (1548-1600) 意大利布鲁诺(1548-1600)接受哥白尼学说并大力宣传，他甚至认为太阳也不是宇宙中心，无垠的宇宙没有中心。不过，他为坚持自己的这一信念付出了生命的代价。布鲁诺生于那不勒斯附近的诺拉，30岁时在日内瓦曾由于反对加尔文教派入狱。他最先在巴黎大学、牛津大学讲学时宣传空间无

29、限大和地动说，批判亚里士多德和托勒密学说，新教和天主教会均不能接受他的观点。1592年他回意大利后，被宗教裁判所监禁。他本来可以选择放弃自己的观点而被释放，但却选择了不放弃自己的观点。1600年，布鲁诺被烧死在罗马鲜花广场。开普勒的老师第谷布拉赫 丹麦人第谷布拉赫(1546-1601) 14岁在哥本哈根大学读书时就预见了一次日食，这使他名声大振，后成为宫廷天文学家。 第谷未接受哥白尼学说，但在福堡天文台观测天象达20多年，把前人星表中错误一个个纠正过来。他是历史上用肉眼观测天象最伟大的人物。 经几次迁徙，他晚年定居布拉格，并收德国人开普勒(1571-1630)为弟子。 Tycho Brahe

30、was a brilliant astronomer and scientist of his time, and has had a big significance on the development of astronomy, science in general, and our view of the world. He is especially famous for two particular things, his damaged nose, and his death. His astronomical achievementsTycho Brahe made a rem

31、arkable star catalogue of over 1000 stars. This was not the biggest catalogue in the number of stars, but in accuracy. His improvements of methods and accuracy in observations was very significant. He proved that comets are not objects in the atmosphere. He showed irregularities in the moons orbit.

32、His wall quadrant and other instrument became widely copied and lead to improved stellar instruments. Kepler used Tycho Brahes observations when he constructed his famous laws of planetary movement. His life in a few important years1566. Tycho Brahe studies in Rostock. His nose is damaged in an acci

33、dent. 1572. A supernova appears in the sky in the formation Cassiopeia. Tycho Brahe observes it carefully, and publishes his findings about the new star, Stella Nova in latin, and becomes known as a respected astronomer. See also observations. 1576. Tycho Brahe received the island Hven from king Fre

34、drik II. 8/8 1576. The foundation of the castle Uranienborg om the island. Tycho Brahe studies the stars (take a look!) at Uranienborg and Stjerneborg. 1597. Tycho Brahe looses the royal support and leave the island. Tycho goes to Wandsbech (near Hamburg) and then to Prag. Emperor Rudolf II gives hi

35、m the castle Benatky 30 km from Prag, but he later moves to a house in Prag suited for observations. 1600. Johannes Kepler is employed as an assistant. 1601. Tycho Brahe dies. Kepler writes down his last words: Ne frustra vixisse videar (May I not seemed to have lived in vain). 开普勒 大概由于哥白尼体系的数学 简单性和

36、和谐性，大学读书 时开普勒成了哥白尼学说的信奉者，但他开始正式职业是编流行的占星术历书，并试图把五种不同的正多面体叠套起来，把行星运行轨道安排在它们相互内切和外切的球面上。但这一企图并没有什么结果。开普勒三定律three major laws of planetary motion在同第谷合作后，开普勒总算得到发现的机会。他开始接触实际观测来的资料，放弃了以前的神秘主义幻想。开普勒先从第谷留给他的火星资料开始研究，发现没有任何一种圆的复合轨道能与其相符。经几次尝试和计算，他终于发现火星轨道是一个椭圆。开普勒欣喜之余把这一发现推广到所有行星，继而发现了三条定律：(1)行星运行的轨道是椭圆，太阳在

37、椭圆的一个焦点上。(2)单位时间内行星中心同太阳中心的连线(向径)扫过的面积相等。(3)行星在轨道上运行一周的时间的平方和它至太阳的平均距离的立方成正比(T2=KR3)。这就是著名的开普勒行星三定律：轨道定律、面积(速度)定律和周期定律。 German astronomer who discovered three major laws of planetary motion, conventionally designated as follows: (1) the planets move in elliptical orbits with the Sun at one focus; (2

38、) the time necessary to traverse any arc of a planetary orbit is proportional to the area of the sector between the central 这三条定律打破了以往天文学家把行星轨道视为正圆、把速度视为均匀的观念。中国的古代天文学家中早有人认识到行星运动的不均匀性。 地球绕日运动的不均匀性表现在1月初(1月3日地球在近日点)在地球上看到太阳在恒星背景上运动得快，7月初(7月4日地球在远日点)在地球上看到太阳在恒星背景上运动得慢。并使人们对已观测到的行星运行周期同它与太阳的距离有了更科学的理解

39、。 开普勒的发现使哥白尼学说的几何简单性和完善性真正体现出来了，因而为这个学说奠定了不可动摇的基础(而对于宗教感情深厚的开普勒来说，他找到的是世界创造者-上帝头脑中的数学和谐)。 伽利略的研究 伽利略(1564-1642)最初的科学生涯主要是对力学的研究。 1597年，伽利略从开普勒那里了解了哥白尼的学说，便对天空发生了兴趣。造望远镜指向天空 1608年的一天，荷兰眼镜商汉斯利佩希发明望远镜，向政府递交专利申请，但只得到一笔奖金。10个月后，伽利略听到这个消息，自己动手制造了一架望远镜，把它指向了天空。伽利略的这一举动标志着天文学研究从古代的肉眼观测进入了望远镜观测的时代。 发现新宇宙他看到了

40、激动人心的景象：月面上的山丘和凹坑，木星的四颗卫星，金星的盈亏，太阳的黑子和自转，茫茫银河中的无数恒星。这使他成了哥白尼学说的坚定信奉者，因为他已看到木星正是一个小太阳系。他的发现在1610-1613年公布时轰动了学术界，人们说：哥伦布发现了新大陆，伽利略发现了新宇宙。Right: Galileo Galileis The Phases of the MoonImage courtesy of Biblioteca Nazionale - Florence, Italy他被教廷申斥 但他的发现用实验事实支持了哥白尼的学说，罗马教廷警告了他。据说当伽利略面临和布鲁诺相似的情境时，在教廷面前不得不

41、在口头上答应放弃自己的观点，不过却在嘴里自言自语：“但是，地球它仍然是在转动啊。” 1632年，他在软禁中写托勒密和哥白尼两大世界体系对话在荷兰出版。书中伽利略以生动的三人对话形式支持哥白尼，还用运动的相对性来说明地球上的人认识地日运动时的情况。这部著作给他带来教廷的申斥和终生监禁。最后他在双目失明中孤独地死去。临死前4年，英国诗人弥尔顿访问了这位双目失明的老人，回去写了一部主张言论和出版自由的著作，但意大利的科学在伽利略之后再没有突出的光彩了。GALILEOS IMPRISONMENT APARTMENT 发现摆的等时性 伽利略对现代科学最大的贡献在力学方面。在比萨大学读书时，常到教堂欣赏壁

42、画和雕刻。一天黄昏，观察教堂里一盏吊灯摆动，发现摆幅越来越小，速度越来越慢，摆一个周期所需时间大致相等。发明摆的等时性，并利用来测量病人脉搏。落体定律 伽利略另一个发现是落体定律。在伽利略之前，已有人做过落体实验。但伽利略早负盛名，流传说法是他在比萨大学教书时，在斜塔上做了落体实验。他确实设想，没有空气阻力的真空中，所有物体以同一速度自由下落。 伽利略用逻辑推理反驳亚里士多德：轻重不同两物捆在一起，它们将如何运动?据亚里士多德，轻物将延缓重物运动；同样据亚里士多德，两物重量更重，又该以更快速度下落。这显然是自相矛盾的。伽利略不登比萨斜塔就已得出令人信服的结论，推翻了亚里士多德的权威性意见。触及

43、牛顿定律 伽利略通过斜面实验发现S=1/2g2的自由落体定律。这是由于斜面坡度按比例延长了在重力作用下运动小球的路程和所需时间，因而便于观察记录和计数。 这一实验中，当小球从斜面上落下沿平面向前匀速滚动时，伽利略设想，如没有表面摩擦力，小球将无限运动下去。 因而这里又产生了新发现：力是运动产生和改变的原因，没外力作用，物体将保持原来静止或匀速运动状态。这实际上是对惯性定律的最初表述，并涉及牛顿第二定律-力是改变物体运动的原因。 不过，伽利略只是正确地提出了这个问题，最后完整表述这两个定律的是牛顿。发现运动的叠加 伽利略的第三个重要发现是运动叠加 原理。这是在研究抛体运动时发现 的。尽管当时的工

44、程师已发现抛体运 动轨迹是条曲线，大炮仰角为45时 射程最远，但却没能给严格证明。 伽利略认为水平方向匀速直线运动和垂直方向的自由落体运动同时存在于抛体上，互不干扰合成一种运动。他把两种运动分解，用几何方法证明抛体运动的轨迹是条抛物线，在仰角为45时水平距离最远。他的研究开始把复杂运动分解为若干简单运动的运动学研究方法。Italian scientist and philosopher. Galileo was a true Renaissance man, excelling at many different endeavors, including lute playing and pa

45、inting. He attended medical school in Padua. While in a cathedral, he noticed that a chandelier was swinging with the same period as timed by his pulse, regardless of its amplitude. He began to study the isochronism of the pendulum in 1581, as well as the motion of bodies. Using an inclined plane, h

46、e showed that all bodies fall at the same rate. He also investigated cohesion, and concluded that a waterfall breaks when the weight of the water becomes too great, the same reason that water pumps could only raise water by 34 feet. Galileo described his views on dynamics and statics in Dialog on th

47、e Two New Sciences, which emphasized mathematics over rhetorical arguments. Galileo was one of the earliest to propose abstract dynamical theories which were ideal and would not be observed under less than ideal circumstances. Galileo observed the supernova of 1604 and tried unsuccessfully to measur

48、e its parallax. According to Copernicuss theory, the Earths motion must produce a parallax, but no such parallax was found until Bessel. Galileo grew interested in the heavens, and built his own a telescope in 1609 after the discovery of lenses was reported from Holland. Galileo used his 30 power te

49、lescope to discover craters on the Moon, sunspots which rotated with the Sun, the four largest satellites of Jupiter, and phases of Venus. This last observation demonstrated that the Copernican theory was correct, since phases would only be observed if Venus were always closer to the sun than to the

50、 Earth. Galileo published his observations in Siderius Nuncius (The Starry Messenger) (1611). For some famous quotes and diagrams from Siderius Nuncius, see MacRobert (1990). A complete translation is contained in van Helden (1989). Galileo also proposed Galilean relativity, which states that the sa