Copernicus: A Reluctant Revolutionary

ASTRONOMY 9: HISTORYOF COSMOLOGY Handout #13 Copernicus: A Reluctant Revolutionary I. Nicolas Copernicus (1473 1543, Poland) Moves Sun back to (aell, near) center Revolutionary implications: - Earth is just another planet going round the sun - Demolisl~esAristotelian spheres and walled-in nlediesal Christian universe - Universe becomes vast (lack of parallax) - Erases division of earthly vs. celestial realms - Aristotelian physics unsatisfactory: where is the center? - Breaks the close link between man, god, and universe - Loss of stability, rest, order - ,The Greeks did not discover all scie~ltificknorvledge Idea that our place in universe is not special: still called the Copernican Principle But these re\-olutionary ideas mere not trumpeted (or even consciously recognized) by Copernicus! Merely implied by his work Heliocentric idea at first welcomed b?- relativel?. ope~l-mindedChurch! Big trouble onl?- decades after death of Copernicus, around 1600 Copernicus was conservative, backward-looking, unwitting instigator of his revolution Last Aristotelian of the great scientists, a t home in the medieval cosmos By standards of his day, Copernicus vias a relic of an earlier world view! - Aristotelian physics long called into question by Bacon, Oresme, Cusa. ... - Aristarchus' heliocentric ideas never really forgotten. and were discussed openly prior to Copernicus - Winds of humanist Renaissance blowing from Italy, little effect on Copernicus despite his studies at Bologna - Still answering Plato's challenge to "save the phenomena", not trying to revolutionize cosmology Blind faith in ancient authority - Data mostly from Ptolemy - Only 2 i recorded observatio~lsof his o a n , didn't bother to get modern instrunlents - Spent a lot of energy accou~lting for \-ariation (not really there) in precession of equinoxes Other inlportant revolutions going on - Luther's 95 T h c s c s and Reformation - Inventio~l of printing press rise of vernacular - ,Journey of Columbus Europe is not the center of the world? Caged in almost Pythagorean secret?., little courage of conviction, plagued by doubts and fears of ridicule (but little threat of religious persecution) ,The Copernican system - Introduces even m o r e epicylces than Ptolem?-! (About 48 vs. 40) - No real observational i~nprovement over Ptolem?- Only circular motions - Sun is displaced from center of orbits as bad as the despised equants! Born of w-ealthy merchant parents. influenced b?- overbearing uncle Lucas and scandalous brother Andreas Studies some astronomy at Univ of Cracow (149Us) Studies Canon law- at Bologna (1496) Studies medicine at Padua (1301) Cuslly job as Canon of Frauenburg cathedral, few- responsibilities Unsocial life largely spent loclied aviay in lonely tower a t Frauenburg Few human relationships: lived w-ith houselieeper . h n a Schillings until ordered by C l ~ u r c lto ~ get rid of her (Counter Reformation), one close friend (Giese), one disciple (Rheticus) Motivation for heliocentric idea: Ptolemy's equants not in accord with Aristotelian ph?-sics! Commentariolus (Little Commentary): preliminary announcement of heliocentric idea, manuscript only, 1510 1514 Seven axioms: A) Heavenl?. bodies do not all move round same center B) Earth is center of moon's orbit and terrestrial gravity, but not universe C) Sun is the center of the universe D) Earth's distance from Sun mucl~smaller than to stars E) Earth's rotation causes daily rising and setting F) Annual motion of Sun against fised stars due to Earth's orbit G) Retrograde notion also due to heliocentric orbits First Account: written by Rheticus, no nlention of Copernicus by name, 1539 On the neuolut%onsof the Heavenbg Spheres, 1543. one of the worst-selling books in history! Not placed on Index of forbidden boolis for 73 ?-ears Copernicus delays publication for decades, finally gives in to pressure from Rheticus and Giese In dedication to Pope, Copernicus mentions Giese and others who influenced him, but not Rheticus! Rheticus demoted from Dean a t 1Vittenburg to mere cushy Prof at Leipzig due to his l~omosesualit?Leaves publicatio~~ of Rcuolutions to pal Osiander Osiander views heliocentric idea as mere calculating hypothesis, does not believe in its t ~ n t h Anonymously adds preface which goes too far in appeasing theologians: Copernicus merely "saving the phenomena" Died of cerebral hemorrhage 1543, may have just see11 published copy of Itevolut%ons 7citl1 Osiander's preface Hit on idea of ellipse for planetary motions, but for the wrong reasons and by faulty logic! Crossed out in manuscript Given Copernicus' trepidation and lack of originality and courage, why 7casn't heliocentric nod el hit on earlier? - Ph?-sics wasn't there yet deficiencies in Aristotle recognized, but no replacement yet - Copernicus was really interpreting Ptolem?;, not nature; vaste of time to humanist scientists \Vh?- does Copernicus get all the attention? - He systematized the heliocentric idea into a cosn~ological nod el (though one rooted in the past) - 1Vritings attract notoriety (mostly heresa?-) a t the right time 11. Thomas Digges (1546 1595. England) 'Translated part of Copernicus' Rcuolutions Leader of Englisl~Copernicans Precise obserl-ations of rycho's (1573) SN Lack of par all^^ implied very large distance Added a new idea to Copernican model: infinite space. viith stars at varying distances