The Scientific Revolution I
Copernicus to Kepler - The Heliocentric Universe


  1. Origins of  the Scientific Revolution
    1. New approach to study of nature stemming from 12th century renaissance (Chartres school)
    2. The Renaissance (the one we always call "THE Renaissance - 1400 -1600)
      1. Humanism shifts intellectual study to more worldly focus
      2.  Voyages of trade and discovery
        1. demand improvements in cartography and geography
        2. open up new regions of world to study
        3. discovery of New World challenges authority of ancient writers and shakes up traditional Eurocentrism
      3. Artistic developments further study in anatomy and provide better tools for observation and recording information
      4. Johannes Gutenberg (1397-1468)
        1. Invents moveable type in 1430s
        2. Sparks a communication revolution as books and pamphlets become much cheaper
          1. many more items will be published - 13,000 titles by 1500
          2. breaks down monopoly of universities and Church over books
          3. Knowledge becomes more widespread
          4. Collaboration, virtual or real, becomes more widespread
      5. Rise of Hermeticism
        1. inspired by reappearance of ancient texts and explosion of "occult sciences"
        2. held that human body and larger world were connected through a system of hidden correspondences
        3. Nature becomes filled with hidden meanings and unseen forces and associations
        4. Hermeticism sees a divine order in nature framed by underlying mathematical realities
    3.  Reformation breaks down intellectual and spiritual authority
    4. Continuing problem of calendar reform focuses attention on astronomy
  2. Ptolemy and Aristotle - The pre-Scientific Revolution paradigm

    1. The basic scientific paradigm of late medieval Europe depended primarily on two men - Aristotle and Ptolemy

      1. Aristotle - Greek philosopher, 384-322 BC - established fundamentals of logic, expanded on Plato's development of a geo-centric universe.

      2. Ptolemy - Greek astronomer, 87 -150 AD - developed a system for predicting movement of planets based on a geocentric (Earth-centered) universe (followed Aristotle in using circles within circles to describe planetary motion.)

    2. Features of the Ptolemaic/Aristotelian paradigm

      1. Earth is at center of the universe

      2. The heavens are perfect (hence, everything in the heavens is a perfect circle or a sphere)

      3. Planets, moon, and sun are attached to crystalline spheres that rotate through the heavens

      4. Since Earth is clearly imperfect, it is very different from the heavens, and vice versa

      5. Personal observation can be fully trusted (We know the Sun goes around the Earth because that's what it looks like it does)

      6. Ancient thinkers are the best source of knowledge (particularly the Greeks, Romans, and the Bible)

      7. Some aspects of the universe are inherently mysterious, known only to God

    3. By Copernicus's time, this was already in trouble

  3. Nicolaus Copernicus (1473-1543)

    1. Polish mathematician and astronomer; also a church administrator

    2. Recognized that Ptolemaic system was in trouble, exceedingly complicated and poor at making accurate predictions

    3. Proposed in his book, On the Revolution of Heavenly Spheres (1543), that the problems with Ptolemy could be solved by putting Sun at center - heliocentric universe

      1. Formulated as an hypothesis - does not seek to prove it through observation or proposed tests

      2. Solves the the problem of retrograde (backwards) motion of planets, the perennial theoretical problem in astronomy for millennia

      3. Remains committed to a number of ancient ideas

        1. Keeps planets on crystalline spheres, which rotate because that is the natural motion of spheres

        2. Since they are attached to perfect spheres, the planets move in circular orbits

        3. Meant to preserve as much as possible of the Aristotelian universe, but no longer geo-centric.

      4. Solves motion problem in a neo-Aristotelian fashion - We don't fly off the spinning Earth because of our natural tendency to be drawn to the Earth and we share in its circular motion

      5. Like Ptolemy, still needs complex system of orbits within orbits to make predictions

    4. Not adopted by many people at the time

      1. Unfortunately, his system did a worse job of predicting motion of planets than Ptolemy

      2. Many people remained convinced we would fly off a spinning Earth

      3. Because stars show no parallax (to the naked eye), Copernicus's system required an immense universe, which was unacceptable to most

  4. Tycho Brahe (1546-1601)

    1. Wealthy Danish noble, devoted life to astronomy

    2. Would build most advanced observatory in Europe and collect some of the best available observations

    3. While he rejected Copernicus, made observations that severely challenged the Ptolemaic system

      1. Using parallax (or lack of it) showed that the nova of 1572 really was a "new star" and not an atmospheric phenomenon

        1. Able to show the nova was as far away as the stars

        2. This meant the heavens were not as immutable as previously thought

      2. Also able to use parallax to show comet of 1577 was not an atmospheric phenomenon

        1. Again shows heavens not completely immutable

        2. Also shoed that comet seemed to travel through the "solid" crystalline spheres the planets were supposed to be attached to

    4. Proposed a geoheliocentric universe

      1.  Sun and moon orbit unmoving Earth, while other planets orbit Sun

      2. Seemed to be better at predicting motion of planets than Copernican heliocentrism

  5. Johannes Kepler (1571-1630)

    1. Mathematician, astronomer, early convert to Copernican system

    2. The Cosmographic Mystery (1597)

      1. Proposed that the orbits of  planets adhered to the five perfect solids

      2. This was wrong, but it worked well enough that it got him hired by Brahe

      3. Also, represented an early attempt at a completely mathematical model for the universe.

    3. Because of class and intellectual differences, Brahe and Kelper did not get along, and Kepler did not gain access to all of Brahe's observation until Brahe died

    4. Astronomia Nova (1609)

      1. Solved basic problem of Copernican system by dispensing with crystalline spheres and perfect circles (by getting rid of them).

      2. First two of his three laws of planetary motion

        1. Planets move in ellipses, with Sun at one focus of the ellipse

        2. Radii sweep out an equal area in equal time period for all part of the orbit

    5. Harmonice Mundi (1619) included the third law

      1. the square of the time of a planets orbit is proportional to the cube of its radius

      2. This boiled planetary motion down to a simple mathematical formula; highly unusual for the time

    6. Dissertatio cum Nuncio Sidereo (1610) provided strong support to Gallileo's work on moons of Jupiter

    7. Largely ignored in his own lifetime

      1. A genuinely fully mathematical model of the universe that completely ignores Aristotle and Ptolemey.

      2. Would be extremely influential on Newton (who showed that Kepler's model still needed some tweaking).