Monday, June 23, 2008

Copernicus, Vesalius, & the Scientific Revolution


Nicolaus Copernicus was born in 1473 and died May 24, 1543. Legend has it that the first printed copy of De revolutionibus orbium coelestium was placed in Copernicus's hands on the very day he died, allowing him to take farewell of his opus vitae (life's work). He is reputed to have woken from a stroke-induced coma, looked at his book, and died peacefully. The De revolutionibus is the first instance of a computational heliocentric model, with the Sun at the center of the solar system/universe (prior models for heliocentrism were philosophic and not mathematical in nature). His assumptions:



1) There is no one center of all the celestial circles or spheres.
2) The center of the earth is not the center of the universe, but only of gravity and of the lunar sphere.
3) All the spheres revolve about the sun as their mid-point, and therefore the sun is the center of the universe.
4) The ratio of the earth's distance from the sun to the height of the firmament is so much smaller than the ratio of the earth's radius to its distance from the sun that the distance from the earth to the sun is imperceptible in comparison with the height of the firmament.
5) Whatever motion appears in the firmament arises not from any motion of the firmament, but from the earth's motion. The earth together with its circumjacent elements performs a complete rotation on its fixed poles in a daily motion, while the firmament and highest heaven abide unchanged.
6) What appear to us as motions of the sun arise not from its motion but from the motion of the earth and our sphere, with which we revolve about the sun like any other planet. The earth has, then, more than one motion.
7) The apparent retrograde and direct motion of the planets arises not from their motion but from the earth's. The motion of the earth alone, therefore, suffices to explain so many apparent inequalities in the heavens.

The publication of De revolutionibus orbium coelestium in 1543 is cited as the beginning of the Scientific Revolution.

A second important scientific publication from 1543 was De humani corporis fabrica, by Andreas Vesalius. This is one of the most influential books in human anatomy & Vesalius is often refered to as the father of human anatomy. "His work is associated with a decisive break with medieval practices. Previously, the teaching of human anatomy derived primarily from texts and dissections were performed as a support for their authoritative opinion. The anatomy lesson consisted of reading by a lector accompanied by a dissection by a barber-surgeon whose work was directed and indicated by an explicator. In essence, the knowledge and practice of anatomy were discrete categories. Vesalius, by contrast, combined commentary and dissection to produce an anatomy based on experience and direct observation rather than on authority (1)." Of note, Vesalius' anatomy was in conflict with the established veiws based on Galen's research, and corrected many of the errors inherit in Galen's views.

A copy of the book can be found here: http://vesalius.northwestern.edu/



- all links are to wikipedia except as noted.
(1) http://www.bronwenwilson.ca/physiognomy/pages/biographies.html

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