Frases de Johannes Kepler

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Johannes Kepler

Data de nascimento: 27. Dezembro 1571
Data de falecimento: 15. Novembro 1630

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Johannes Kepler foi um astrônomo e matemático alemão. Considerado figura-chave da revolução científica do século XVII. É mais conhecido por ter formulado as três leis fundamentais da mecânica celeste, conhecidas como Leis de Kepler, codificadas por astrônomos posteriores com base em suas obras Astronomia Nova, Harmonices Mundi, e Epítome da Astronomia de Copérnico. Essas obras também forneceram uma das bases para a teoria da gravitação universal de Isaac Newton.

Durante sua carreira, Kepler foi professor de matemática em uma escola seminarista em Graz, Áustria, um assistente do astrônomo Tycho Brahe, o matemático imperial do imperador Rodolfo II e de seus dois sucessores, Matias I e Fernando II. Também foi professor de matemática em Linz, Áustria, e conselheiro do general Wallenstein. Adicionalmente, fez um trabalho fundamental no campo da óptica, inventou uma versão melhorada do telescópio refrator e ajudou a legitimar as descobertas telescópicas de seu contemporâneo Galileu Galilei.

Kepler viveu numa época em que não havia nenhuma distinção clara entre astronomia e astrologia, mas havia uma forte divisão entre a astronomia e a física . Kepler também incorporou raciocínios e argumentos religiosos em seu trabalho, motivado pela convicção religiosa de que Deus havia criado o mundo de acordo com um plano inteligível, acessível através da luz natural da razão. Kepler descreveu sua nova astronomia como "física celeste", como "uma excursão à Metafísica de Aristóteles" e como "um suplemento de Sobre o Céu de Aristóteles", transformando a antiga tradição da cosmologia física ao tratar a astronomia como parte de uma física matemática universal.

Citações Johannes Kepler

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„I much prefer the sharpest criticism of a single intelligent man to the thoughtless approval of the masses.“

— Johannes Kepler
As quoted in (K)new Words: Redefine Your Communication (2005) by Gloria Pierre, p. 147

„Given ships or sails adapted to the breezes of heaven, there will be those who will not shrink from even that vast expanse.“

— Johannes Kepler
Context: It is not improbable, I must point out, that there are inhabitants not only on the moon but on Jupiter too, or (as was delightfully remarked at a recent gathering of certain philosophers) that those areas are now being unveiled for the first time. But as soon as somebody demonstrates the art of flying, settlers from our species of man will not be lacking. Who would once have thought that the crossing of the wide ocean was calmer and safer than of the narrow Adriatic Sea, Baltic Sea, or English Channel? Given ships or sails adapted to the breezes of heaven, there will be those who will not shrink from even that vast expanse. Therefore, for the sake of those who, as it were, will presently be on hand to attempt this voyage, let us establish the astronomy, Galileo, you of Jupiter, and me of the moon. Translated by Edward Rosen, Kepler's Conversation with Galileo's Sidereal Messenger (1965), p. 39 Unsourced variant translation: Provide ships or sails fit for the winds of heaven, and some will brave even that great void.

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„I reply in a single word to the sentiments of the saints on these questions about nature; in theology, to be sure, the force of authorities is to be weighed, in philosophy, however, that of causes“

— Johannes Kepler
Context: Indeed I reply in a single word to the sentiments of the saints on these questions about nature; in theology, to be sure, the force of authorities is to be weighed, in philosophy, however, that of causes. Therefore, a saint is Lactantius, who denied the rotundity of the earth; a saint is Augustine, who, admitting the rotundity, yet denied the antipodes; worthy of sainthood is the dutiful performance of moderns who, admitting the meagreness of the earth, yet deny its motion. But truth is more saintly for me, who demonstrate by philosophy, without violating my due respect for the doctors of the church, that the earth is both round and inhabited at the antipodes, and of the most despicable size, and finally is moved among the stars. Vol. III, p. 156

„If you want the exact moment in time, it was conceived mentally on 8th March in this year one thousand six hundred and eighteen, but submitted to calculation in an unlucky way, and therefore rejected as false, and finally returning on the 15th of May and adopting a new line of attack, stormed the darkness of my mind.“

— Johannes Kepler
Context: If you want the exact moment in time, it was conceived mentally on 8th March in this year one thousand six hundred and eighteen, but submitted to calculation in an unlucky way, and therefore rejected as false, and finally returning on the 15th of May and adopting a new line of attack, stormed the darkness of my mind. So strong was the support from the combination of my labour of seventeen years on the observations of Brahe and the present study, which conspired together, that at first I believed I was dreaming, and assuming my conclusion among my basic premises. But it is absolutely certain and exact that "the proportion between the periodic times of any two planets is precisely the sesquialterate proportion of their mean distances..." Book V, Ch. 3 dates that his Third Law of Planetary Motion occurred to him, translation by E. J. Aiton, A. M. Duncan, and J. V. Field, The Harmony of the World (1997), Vol. 209, p. 411 Variant translation: A fresh assault overcame the darkness of my reason... As quoted in Calculus. Multivariable (2006) by Steven G. Krantz and Brian E. Blank. p. 126

„I am indeed casting the die and writing the book, either for my contemporaries or for posterity to read, it matters not which: let the book await its reader for a hundred years; God himself has waited six thousand years for his work to be seen.“

— Johannes Kepler
Context: Now because 18 months ago the first dawn, 3 months ago broad daylight but a very few days ago the full sun of the most highly remarkable spectacle has risen — nothing holds me back. I can give myself up to the sacred frenzy, I can have the insolence to make a full confession to mortal men that I have stolen the golden vessel of the Egyptians to make from them a tabernacle for my God far from the confines of the land of Egypt. If you forgive me I shall rejoice; if you are angry, I shall bear it; I am indeed casting the die and writing the book, either for my contemporaries or for posterity to read, it matters not which: let the book await its reader for a hundred years; God himself has waited six thousand years for his work to be seen. Book V, Introduction Variant translation: It may well wait a century for a reader, as God has waited six thousand years for an observer. As quoted in The Martyrs of Science; or, the Lives of Galileo, Tycho Brahe, and Kepler (1841) by David Brewster, p. 197. This has sometimes been misquoted as "It may be well to wait a century for a reader, as God has waited six thousand years for an observer." Variant translation: I feel carried away and possessed by an unutterable rapture over the divine spectacle of heavenly harmony... I write a book for the present time, or for posterity. It is all the same to me. It may wait a hundred years for its readers, as God has also waited six thousand years for an onlooker. As quoted in Calculus. Multivariable (2006) by Steven G. Krantz and Brian E. Blank. p. 126 Variant translation: I am stealing the golden vessels of the Egyptians to build a tabernacle to my God from them, far far away from the boundaries of Egypt. If you forgive me, I shall rejoice.; if you are enraged with me, I shall bear it. See, I cast the die, and I write the book. Whether it is to be read by the people of the present or of the future makes no difference: let it await its reader for a hundred years, if God himself has stood ready for six thousand years for one to study him. Unsourced translation

„Just as the eye was made to see colours, and the ear to hear sounds, so the human mind was made to understand“

— Johannes Kepler
Context: Just as the eye was made to see colours, and the ear to hear sounds, so the human mind was made to understand, not whatever you please, but quantity. I. 31 as quoted by Edwin Arthur Burtt in The Metaphysical Foundations of Modern Physical Science

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„I was almost driven to madness in considering and calculating this matter. I could not find out why the planet would rather go on an elliptical orbit. Oh, ridiculous me!“

— Johannes Kepler
Context: I was almost driven to madness in considering and calculating this matter. I could not find out why the planet would rather go on an elliptical orbit. Oh, ridiculous me! As the liberation in the diameter could not also be the way to the ellipse. So this notion brought me up short, that the ellipse exists because of the liberation. With reasoning derived from physical principles, agreeing with experience, there is no figure left for the orbit of the planet but a perfect ellipse. Ch.58, as quoted in John Freely, Before Galileo: The Birth of Modern Science in Medieval Europe (2012)

„Of a number of variant hypotheses about the same facts, that one is true which shows why facts, which in the other hypotheses remain unrelated, are as they are, i.e., which demonstrates their orderly and rational mathematical connexion.“

— Johannes Kepler
Context: Of a number of variant hypotheses about the same facts, that one is true which shows why facts, which in the other hypotheses remain unrelated, are as they are, i. e., which demonstrates their orderly and rational mathematical connexion. Vol. I, p. 238

„Now because 18 months ago the first dawn, 3 months ago broad daylight but a very few days ago the full sun of the most highly remarkable spectacle has risen — nothing holds me back.“

— Johannes Kepler
Context: Now because 18 months ago the first dawn, 3 months ago broad daylight but a very few days ago the full sun of the most highly remarkable spectacle has risen — nothing holds me back. I can give myself up to the sacred frenzy, I can have the insolence to make a full confession to mortal men that I have stolen the golden vessel of the Egyptians to make from them a tabernacle for my God far from the confines of the land of Egypt. If you forgive me I shall rejoice; if you are angry, I shall bear it; I am indeed casting the die and writing the book, either for my contemporaries or for posterity to read, it matters not which: let the book await its reader for a hundred years; God himself has waited six thousand years for his work to be seen. Book V, Introduction Variant translation: It may well wait a century for a reader, as God has waited six thousand years for an observer. As quoted in The Martyrs of Science; or, the Lives of Galileo, Tycho Brahe, and Kepler (1841) by David Brewster, p. 197. This has sometimes been misquoted as "It may be well to wait a century for a reader, as God has waited six thousand years for an observer." Variant translation: I feel carried away and possessed by an unutterable rapture over the divine spectacle of heavenly harmony... I write a book for the present time, or for posterity. It is all the same to me. It may wait a hundred years for its readers, as God has also waited six thousand years for an onlooker. As quoted in Calculus. Multivariable (2006) by Steven G. Krantz and Brian E. Blank. p. 126 Variant translation: I am stealing the golden vessels of the Egyptians to build a tabernacle to my God from them, far far away from the boundaries of Egypt. If you forgive me, I shall rejoice.; if you are enraged with me, I shall bear it. See, I cast the die, and I write the book. Whether it is to be read by the people of the present or of the future makes no difference: let it await its reader for a hundred years, if God himself has stood ready for six thousand years for one to study him. Unsourced translation

„Nothing which consists of corporeal matter is absolutely light, but that is comparatively lighter which is rarer“

— Johannes Kepler
Context: Nothing which consists of corporeal matter is absolutely light, but that is comparatively lighter which is rarer, either by its own nature, or by accidental heat. And it is not to be thought that light bodies are escaping to the surface of the universe while they are carried upwards, or that they are not attracted by the earth. They are attracted, but in a less degree, and so are driven outwards by the heavy bodies; which being done, they stop, and are kept by the earth in their own place. As quoted by Bryant, ibid.

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