New To Our On The Shoulders Of Giants Series, This Groundbreaking Work Of Astronomy Proposed A Heliocentric Universe In Which Planets Orbited The Sun Daring To Challenge The Ptolemaic Ideal Of The Earth As The Center Of The Universe This Essay By Copernicus , Revolutionized The Way We Look At The Earth S Placement In The Universe, And Paved The Way For Many Great Scientists, Including Galileo And Isaac Newton, Whose Theories Stemmed From This Model Featuring A Biography Of Copernicus And An Accessible, Enlightening Introduction, Both Written By The Renowned Physicist Stephen Hawking, On The Revolution Of Heavenly Spheres Provides A Fascinating Look At The Theories Which Shaped Our Modern Understanding Of Astronomy And Physics The Earth is Spherical, Small, Mobile triply so , Certainly Not the Center of the Universe, and thus imperfect from now on.Having said that, so far as hypotheses are concerned, let no one expect anything certain from Science, which cannot furnish it, lest he accept as the truth ideas conceived for another purpose, and depart from this study a greater fool than when he entered it Farewell. And though all these things are difficult, almost inconceivable, and quite contrary to the opinion of the multitude, nevertheless in what follows we will with God s help make them clearer than day at least for those who are not ignorant of the art of mathematics The Copernican Revolution has become the prime exemplar of all the great transformations in our knowledge of the world a symbol of scientific advance, the paradigmatic clash of reason and religion, a shining illustration of how cold logic can beat out old prejudices Yet reading this groundbreaking book immediately after attempting Ptolemy s Almagest the Bible of geocentric astronomy reveals far similarities than differences Otto Neugebauer was correct in calling Copernicus s system an ingenious modification of Hellenistic astronomy, for it must be read against the background of Ptolemy in order to grasp its significance.The most famous section of De revolutionibus was, ironically, not even written by Copernicus, but by the presumptuous Andreas Osiander, a Lutheran theologian who was overseeing the publication of the book, and who included a short preface without consulting or informing Copernicus Knowing that Copernicus s hypothesis could prove controversial Luther considered it heretical , Osiander attempted to minimize its danger by asserting that it was merely a way of calculating celestial positions and did not represent physical reality for it is not necessary that the hypotheses should be true, or even probable but it is enough if they provide a calculate which fits the observations Though this assertion obviously contradicts the body of the work in which Copernicus argues at length for the reality of the earth s movement , and though Copernicus and his friends were outraged by the insertion, it did help to shield the book from censure And arguably Osiander was being a good and true Popperian believing that science is concerned with making accurate predictions, not in giving us the truth In any case, Osiander was no doubt correct in this assertion For it is sufficiently clear that this art is absolutely and profoundly ignorant of the causes of the apparent irregular movements Neither Ptolemy nor Copernicus had any coherent explanation of what caused the orbits of the planets, which would not come until Einstein.After this little interpolation, Copernicus himself wastes no time in proclaiming the mobility of the earth In retrospect, it is remarkable that it took such a long stretch of history for the heliocentric idea to emerge For it instantly explains many phenomena which, in the Ptolemaic system, are completely baffling Why do the inner planets Venus and Mercury move within a fixed distance of the sun Why does the perigee the closest point in the orbit of the outer planets Mars, Jupiter, Saturn occur when they are at opposition i.e., when they are opposite in the sky from the sun , and why does their apogee the farthest point occur when they are in conjunction when they are hidden behind the sun And why do the planets sometimes appear to move backwards relative to the fixed stars But putting the earth in orbit between Venus and Mars neatly and instantly explains all of these mysteries Mercury and Venus always appear a fixed distance from the sun because they are orbiting within the earth s orbital circle, and thus from our position appear to go back and forth around the sun Mars, Jupiter, and Saturn, by contrast, can appear at any longitudinal distance from the sun because their orbits are outsider ours but if Mars orbit were tracked from Jupiter, for example, it would, like Venus and Mercury, appear to go back and forth around the sun Also note that Mars will appear to go backwards from earth when earth overtakes the red planet, due to our planet s shorter orbital period And since Mars will be closest when it is on the same side of the sun as earth opposition from the sun , and furthest when it is on far side of the sun conjunction with the sun , this also explains the apogee and perigee positions of the outer planets.This allows Copernicus to collapse five circles one for each of the planets, which were needed in the Ptolemaic system to account for these anomalies into one circle namely, the earth s orbit The advantages are palpable Nevertheless, while I think the benefits of putting the planets in orbit around the sun are obvious, perhaps even to a traditionalist, it is not obvious why Copernicus should put the earth in motion around the sun rather than the reverse Indeed, this is exactly what the eminent astronomer Tycho Brahe did, several generations later For it makes no observational difference whether the sun or the earth is in motion And in the Aristotelian physics of the time, the former solution makes a great deal sense, since the heavens were supposed to be constituted of lightest elements and the earth of the heaviest elements So how could the heavy earth move so quickly What is , there is no concept of inertia in Aristotelian physics, and so no explanation for why people would not fly off the earth if it were in rapid motion Copernicus takes a brief stab at answering these obvious counterarguments, even offering a primitive notion of inertia As a matter of fact, when a ship floats on over a tranquil sea, all the things outside seem to the voyagers to be moving in a movement which is the image of their own, and they think on the contrary that they themselves and all the things with them are at rest Even so, it is obvious that such a brief example does not suffice to refute the entire Aristotelian system Clearly, a whole new concept of physics was needed if the earth was to be in motion, one which did not arrive until Isaac Newton, born nearly two hundred years after Copernicus It took a certain amount of boldness, or obtuseness, for Copernicus to proclaim the earth s motion without at all being able to explain how the heaviest object in the universe or so they believed could hurtle through space In structure and content, De revolutionibus follows the Algamest pretty closely beginning with mathematical preliminaries, onward to the orbits of the sun or, in this case the earth , the moon, and the planets with plenty of tables to aid calculation as well as a description of his astronomical instruments and a chart of star locations, and finally ending with deviations in celestial latitude how far the planets deviate north and south from the ecliptic in their orbits Copernicus was even wedded than Ptolemy to the belief that celestial objects travel in perfect circles, which leads him to repudiate Ptolemy s use of the equant the point around which a planet moves at a constant speed The use of the equant upset Copernicus s sense of elegance, you see, since its center is different from the actual orbit s center, thus requiring two overlapping circles Copernicus s own solution was an epicyclet, which revolves twice westward clockwise, from the celestial north pole for each rotation eastward on the deferent And so, ironically, though Ptolemy is sometimes mocked for using epicycles, Copernicus followed the same path I also find it amusing that the combined effect of these circular motions, in both Ptolemy and Copernicus, added up to a non circular orbit clearly nature had different notions of elegance than these astronomers In any case, it would have to wait until Kepler that it was realized that the planets actually follow an ellipse.Perhaps the greatest irony is that Copernicus s book is not any easier to use than Ptolemy s as a recipe book for planetary positions Now, it is far beyond my powers to even attempt such a calculation But in his Very Short Introduction to Copernicus which I recommend , Owen Gingerich takes the reader through the steps to calculation the position of Mars on Copernicus s birthday February 19, 1473 To do this you needed the radix, which is a root position of the planet recorded at a specified time and you also need the planet s orbital speed the time needed for one complete orbit, in this case 687 days The year must be converted into sexigesimal base 60 system, and then converted in elapsed Egyptian years which lack a leap year , in order to calculate the time elapsed since the date of the radix s position in this case is January 1st, 1 AD Then this sexigesimal number can be looked up in Copernicus s tables but this only gives us the location of Mars with respect to the sun To find out where it will appear in the sky, we also need the location of earth, which is another tedious process You get the idea.I read the bulk of this book while I was on vacation in rural Canada Faced with the choice between relaxation or self torture, I naturally chose the latter While most of my time was spent scratching my head and helplessly scratching the page with a pencil, the experience was enough to show me as if I needed demonstration after Ptolemy that astronomy is not for the faint of heart, but requires intelligence, patience, and care.There was one advantage to reading the book on vacation For it is the only time of year when I am in a place without light pollution The stars, normally hiding behind street lights and apartment buildings, shone in the hundreds I would have seen even were it not for the waxing moon But this did give me the opportunity to get out an old telescope bought as a birthday present for a cousin, over a decade ago and examine the moon s pitted surface It is humbling to think that even such basic technology was years ahead of Copernicus s time.Looking at the brilliant grey circle, surrounded by a halo of white light, I felt connected to the generations of curious souls who looked at the same moon and the same stars, searching for answers So Copernicus did not, in other words, entirely spoil my vacation. Thanks for starting the Copernican revolution which greatly impacted the scientific revolution and thereby completely changed our world views We wouldn t be where we are today without you. It wasn t until some 70 years later, helped by Galileo s stubbornness, that the heliocentric universe posited by Copernicus book resulted in the Roman Catholic Church decree that heliocentrism was heresy Copernicus expressed his fear of this reaction, or likely the scorn of the mathematical community, in his Preface and Dedication to Pope Paul III With great humility, he submitted the work as a life long product of observation and study Despite his fears of discarding a thousand years of a Ptolemic, geocentric universe, he asserted that m athematics is written for mathematicians pg 7 Copernicus is quietly assured of the value of his calculations He also finds support from his theory among history Copernicus notes Cicero mentioned Nicetas thought the Earth moved and that Plutarch wrote that Philolaus the Pythagorean said the Earth moved in an obliquely circular motion around the fire interestingly, this is not a reference to the sun because Philolaus though the moon and sun moved around the fire as well And then I get lost Much like the work he was refuting, Ptolemy s Almagest, equations, charts and graphs dominate the book Then again, this book wasn t written for me It was written for mathematicians For those of us unversed in the mechanics of astronomical configuration, we are simply left in awe of those disciplined enough to be so, Even if one has trouble following Copernicus in his proofs, there is something undoubtedly sublime about reading his book, On the Revolutions of the Heavenly Spheres To watch as a 1200 year old geocentric planetary system is dismantled is amazing in itself But like I mentioned, the text is difficult to follow The reader will be up for multiple problems if he or she hasn t read Euclid or Ptolemy I skipped Ptolemy myself, but my exposure to Euclid helped If one bypasses the Almagest then it is advisable to read up on epicycles and stellar parallax beforehand Epicycles are an antiquated theory of, let s just say, an orbit within orbits which was overturned by Kepler and because of this it hasn t made it to us as common knowledge Better to read up a little bit to save oneself some massive confusionit s already a challenging book as it is It is tempting to skip over the elaborate evidence tables found throughout the work, but one really should at least take a look through them The data in these tables show the effect of the changing of our vantage point from the moving earth and how that affects planetary and stellar location This lifetime of data collection is the heart of Copernicus work Basically, it shows that one cannot maintain a geocentric system without allowing distortions and irregular planetary orbits I m not ashamed to say the story behind the text was of a marvel to me than the text itself was I won t pretend to understand material than I actually do However, I still think it is good to take a trip through this landmark book once in one s life. show me deferent and i ll disprove your epicycle I am a fan of Copernicus work, enough said. torun, polska 19 feb 1473 1543 frauenburg, deutschland1543Amherst, NY Prometheus Books, 1995Charles Glenn Wallis, trans.genius gathered together the observations before him, and interpreted them in leaps of deduction and mathematics the method of genius simple the leaps astronomicalGENIUS In De Revolutionibus 1543 , Copernicus published his ground breaking heliocentric theory.During the first millennium, astronomers and theologians used the Ptolemaic system, which in essence consisted of this 1 The earth is in the centre of the cosmos.2 All planets, moon and sun revolve in orbits around the earth this they do in cristalline spheres.3 The outer cirstalline sphere contains all the stars.To accord for all the discrepancies for example some planets, like Venus, have a retrograde motion through the sky had to be solved with obscure mathematical devices like equants, epicylces and deferrents.This led to the practical problem of how cristalline spheres, being made of matter i.e Aristotle s quintessence could account for these mathematical movements Wouldn t the spheres shatter Another practical problem was the use of the Ptolemaic system for calculating the calender During the centuries the discrepancies and flaws built up, so once in a while a reset of the system was necessary A third problem with the Ptolemaic universe was the sheer complexity of movements and mathematical constructs Only the most learned geometricians and astronomers could work with this system One could say that by the time of Copernicus there was a need for a new, accurate and simpler celestial system Copernicus did exactly this He put the sun in the middle of the cosmos, and by doing this was able to come up with a mathematically simpler therefore beautiful system easier to work with, pleasing to the eye of the beholder and logically consistent Ockham s razor simplicity is a criterium to decide between scientific theories.The main problem with this new system was, of course, that theologians and philosophers were basing their whole worldview on Aristotle and Aquinas This didn t leave much room for a heliocentric assumption E.g in the book Joshua it says that Joshua commanded God to let the sun stand still this becomes problematic when you have the sun as a centre of the universe.Another problem or rather collection of problems was that Copernicus system went against common sense notions If the earth is moving around the sun, how come we don t fly off our planet We see the starry heaven, the planets and the sun and moon move through the sky, right This new system sounded highly speculative to contemporaries.A third important point on Copernicus is that he was a neoplatonist During Copernicus time, the works of neoplatonists like Plotinus were re discovered According to this philosopical school, the sun has supernatural powers One can easily see where Copernicus found his motivation to put the sun in the centre of the cosmos and do away with the geocentric worldview In all, this is a historical book, an important turning point in history But it wasn t until Newton s synthesis in 1687 that the Copernican system became part of a whole new philosophy of the world This was because there was no objective, scientific criterium by which to judge between Ptolemy and Copernicus Both had their pros and cons but there was no deciding piece of evidence This piece of evidence was delivered by Galilei, who discovered with his telescope the phases of Venus this showed that Venus revolved around the sun and not the earth He also found many other interesting things with his telescope, to note satellites around other planets, sunspots, craters on the moon s surface, etcIn the decades after the publication of De Revolutionibus, the book largely went by unnoticed apart from some up to date astronomers With the works of Tycho Brahe, Johannes Kepler and Galileo Galilei, the Copernican system became widely diffused in intellectual circles and accessible to non astronomers, and it was only then after Galilei s discoveries with the telescope that the Inquisition put De Revolutionibus on the Index of Forbidden Books.No matter the historical worth of this book, I can t really give this book a high score It is extremely dense and technical I d bet that the average person can read the first 25 pages after this it gets almost impossible to follow I used this book mainly as a source of additional information to a physics textbook I didn t need to read the whole book so take my review with a grain of salt. And then came a voice out of Poland, saying that this earth, footstool of God, and home of his redeeming pilgrimage, was a minor satellite of a minor sun It seemed so simple a thing to say We cannot be moved to fear or wonder by it now We take it for granted that the soil on which we stand is a passing thing, transiently compact of elements that will disintegrate and leave not a wrack behind But to the medieval world, whose whole philosophy had rested on the neighborly nearness of the earth and God, the constant moral solicitude of the Deity for man, this new astronomy was an atheistic blasphemy, a ruthless blow that seemed to overthrow Jacob s Ladder which Faith had built between angels and men.Copernicus book On the Revolutions of the Celestial Orbs was well named, for no book in history has created a greater revolution That pious Polish monk, sitting patiently before the baffling stars, had meant no harm He had no suspicion of the bearings of his thoughts on the future of belief He lost himself in the search for knowledge He was sure that all truths must be good and beautiful and would make men free And so by the magic of his mathematics, he transformed a geocentric and an anthropocentric universe a world that revolved about the earth and man into a kaleidoscope of planets and stars in which the earth seemed but a moment s precipitation of floating nebula Everything was changed distances, significances, destinies And God, who had seemed to inhabit the friendly and flowing clouds, disappeared into the far reaches of illimitable space It was as if the wall of a man s house had been torn down by some blind and angry wind, leaving him ill sheltered in the darkness of infinity.With Copernicus modernity begins With him secularism begins With him, reason makes its French Revolution against the faith immemorially enthroned and man commences his long effort to rebuild with thought the shattered palace of his dreams Heaven becomes mere sky and space and nothingness, who once had hoped for paradise It was as in the fable Plato told, of the gods would care for a man until he had come of age, and then disappeared, leaving him to the devices of his own intelligence It was as in the ancient savage days, the old man of the tribe drove the young men forth and they then seek some other soils to raise upon at their own homes their own happiness With the Copernican revolution, humans were compelled to become of age.
- 408 pages
- De revolutionibus orbium caelestium
- Nicolaus Copernicus
- 02 December 2019 Nicolaus Copernicus