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Paul Halsall
Modern Western Civilization

Class 7: The Scientific Revolution in the Seventeenth Century


I. Introduction

In the last class we looked at the types of ideas people used in the middle ages and the 16th and 17th century to explain the world around them. At the and we saw what elements there were in the world of the time that pushed some men to begin to break the mold of thinking. It was a mold of thinking that just did not continue to fit the observations.

Discrepancy between observations and actuality is one of the springboards of the development of the history of science.

Because the ways of thinking were so set this is a story that lasts a century and a half, from an obscure Polish priest to one of the giants of modern science.

With Copernicus the Scientific Revolution starts.

II. Nicolaus Copernicus (1473-1543)

A Polish priest who studied in Renaissance Italy at the University of Padua - Maths, Astronomy, Medicine and Theology made up the curriculum.

De Revolutionibus Orbium Caelestium On the Revolution of the Heavenly Orbs 1543

Note the importance of printing - Da Vinci (1452-1519) knew all this but did not publish his results.

The idea of a heliocentric universe was a mental breakthrough, but did not offer explanations for the other things, such as motion, that Aristotle's' view of the world did. This had been the reason Ptolemy rejected it.

Copernicus theory was based on very conservative maths and not on observation. Recall Platontists' obsession with simplicity and perfection. It was simpler to explain heavenly motion if the Sun was at the center. Copernicus offered it as a hypothesis. His way reduced the number of spheres from 80 to 34. He was still loyal to Ptolemy's system in many ways.

Copernicus was obsessed with perfect circular motion. He was wrong; he thought that planets moved in a perfect circle (not so), due to Platonic maths. But the important thing was Copernicus' mental breakthrough. He was wrong but was the stimulus for future scientists to come up with something better.

III. Tycho Brahe (1546-1601) Danish Royal Astrologer.

Brahe set new standards in observation without a telescope. (There were no street lights or pollution and it was easier to see sky then than now.)

He disbelieved Copernicus because his observations showed that planets did not move in perfect circles.

In 1572-73 a new star appeared (the Crab Nebula?) and in 1577 a new comet. This went right through any supposed crystal spheres. Neither event sat well with the idea of perfect unchangeable heavens,

Brahe thus junked the idea of perfect circular motion, and the idea of fixed spheres in the heavens.

IV. Johannes Kepler (1571-1630)

Student of maths and astronomy and a student of Brahe.

He put Brahe's observations into order. His method was to test hypothesis after hypothesis until he came up with an answer that worked. Eventually he came up with the idea that planets move in ellipses.

His Three Laws of Planetary Motion corrected Copernicus in light of Brahe's observations. Note also the beginning of the use of the idea of scientists discovering laws.

Planets move in ellipses - of which Sun is one focus.

One law: An equal area of the plane is covered in equal time by planet revolving around the Sun. (or the period of revolution around the sun is proportional to distance from the Sun.)

Kepler had no explanation of why this was the case. In fact he was involved in number mysticism and explained it as part of the mystery of numbers.

The old Aristotelian system was broken, but there was no new synthesis to replaces it. Constructing a new. Equally persuasive synthesis was the achievement of the Scientific Revolution.


V. Galileo Galilei (1564-1642)

Italian. He also studies at Padua, which was a hotbed of scientific discussion, on both the cause of motion and the scientific method. Galileo was also a mathamatician, and was also keen on Archimedes (who was translated in 1543).

There are two main aspects of his work to note.

A. Astronomy

-He used a telescope for better observation c. 1609. He was not however the first to do so.

-This confirmed the heliocentric system. There were also surprises, like seeing the Moon with scars on, seeing sun spots. This was in a supposedly perfect heaven. The difference between Earth and the heavens was disappearing.

-What was really important was that he tied in astronomy to motion on Earth, which had also been the great achievement of Aristotle's system.

B. Motion on Earth

-Galileo also did experiments about motion on Earth. Recall Aristotle's' notion of contiguous motion.

-There is the story of Galileo dropping objects from the Leaning Tower of Pisa to see if heavy things really did fall faster as predicted by Aristotle. (Of course not. Gravity works on each particle separately.) 1591. This is probably not true, but Galileo did argue on the basis of tying two objects together and asking if they would fall more quickly.

-There is also the story of him watching a pendulum swing in Siena Cathedral.

C. 1638 - Discourse on Two New Sciences

- at first passed Church Censors.

What Galileo did here was more important than the debate over astronomy.

HE IMAGINED MOTION WITHOUT ANY OF THE CONSTRAINTS IT FACES IN THE REAL WORLD - A THOUGHT EXPERIMENT WHICH BREAKS THE MOLD.

He based his theories on observation, but would go beyond observation to the truth, since he recognized the constraints on simple observation.

Notion of inertia - a body continues to move unless it is stopped - vital. Not fully developed by Galileo. He thought motion was naturally in a circular direction, rather than a straight line. Also he still had the old medieval idea of impetus in his head.

He did not offer a convincing explanation of heavenly motion.

His importance was that he attacked the whole Aristotelian system. He saw the need for an entirely new view.

D. Opposition from some Church authorities

In 1600, Giordano Bruno had been burnt for suggesting a plurality of worlds, and other heresies. This had led to an intensification of fear about Copernicus' ideas just before Galileo became active.

F. Reading Notes to Galileo Galilei

1615 Letter to Grand Duchess of Tuscany (ruler of Florence).

1. how does Galileo differentiate between the study of physical science and the study of theology? What differences does he see between them?

2. Did Galileo seem to believe in God? What view does he have of the Bible? Why might this view upset Church authorities?

3. From reading elsewhere, how does the Church now characterize its claim to infallibility? [ref. New Catholic Encyclopedia?]

4. Exactly why was Galileo condemned?

G. Was Galileo Totally Right?

There were real problems in his use of scriptures.This was especially true for Bellarmine. Galileo was persistent - he raised the ire of the curia. Some supported him, including Pope Urban VIII.

H. Opposition in Catholic Countries to Science?

-Italy and Spain

-There was more freedom in France (Gallicanism), England and Holland (value of divisions in Europe.)

-The University of Padua was under Venice, the most anti-clerical state in Europe, Copernicus, Galileo, and the medical men Vassalius and William Harvey all studied there.

-Protestants had been as hostile to Copernicus as Catholics, on biblical grounds, but there was less state control in Protestant countries, and in the end Protestantism became more liberal than it was at first.

VI. Problems of Method in Science

As well as all this growth of practical knowledge, there were people considering scientific method.

Bacon and Descartes are especially important. Both decided that all previous beliefs (outside religion) had to be ignored.

A. Francis Bacon (1561-1625) and Induction

English Lord Chancellor. Gay.

It should be noted that he had an enthusiasm for the application of science; for Bacon science was power - HE PROMOTED THE MODERN IDEA OF PROGRESS.

1620 Novum Organum (New Tools)

The Inductive Method; make a lot of observations and then generalize rules of nature. This leads to scientific observation as a method.

What problems can you see? (set by David Hume)

Basically THERE IS NO LOGICAL REASON TO GO ARGUE FROM ANY AMOUNT OF EXPERIENCE TO A GENERAL LAW.

THIS IS THE "PROBLEM OF INDUCTION"

B. Problem of Induction

Basically science is not logical, at least in its observational mode, but this does not mean it is false.

One important modern philosopher of science, Karl Popper, suggests that science proceeds by hypothesizing a reasonable model and then seeing if it fits the evidence. Science does not then discover natural laws but suggests models of the world, although many scientists have thought they were in fact discovering natural laws, and this may have been an essential part of there outlook.

The process we have been discussing here in fact shows this process of creating new models.

C. Bacon and Mathematics

Bacon's great problem was that he never understood the importance of mathematics, which is deductive not inductive since it proceeds from theorems to axioms without empirical observation. Also, although experimentation became the watchword of science, a lot of the breakthroughs in the Scientific revolution were in astronomy and mechanics, and these were mental breakthroughs.


D. Rene Descartes (1596 - 1650) and Deduction

(He will be mentioned again as a general philosopher)

Descartes was a great mathematician and philosopher for instance he showed the any algebraic formula could be plotted on a graph. This was a linking of algebra, which was Hindu and Arab maths, with Geometry, which was the great Greek contribution to maths. It was very important in the future methods of science.

He also looked at what way to get knowledge. IE at the study of epistemology.

1637 Discourse on Method

He advanced the notion of DEDUCTION to get some certain knowledge (such as that you know you yourself exist and work from there).

He stressed Maths was a general science, applicable to all other sciences which were concerned with order and measurement. Note the Platonism here, the stress on Maths as away to knowledge.

This was GOOD in that it stressed Mathematics in science, but BAD in that it seemed to allow little room for testing ideas in the real world.

In fact Descartes was not totally against observation,but his emphasis was different from Bacon.

VII. Isaac Newton (1642-1727)

A professor at Cambridge.

Newton was quite possibly the greatest scientist who ever lived.

1687 - Philosophiae Naturalis Principia Mathematica Mathematical Principles of Natural Philosophy

It brought together Galileo's discoveries about motion on Earth, and Kepler's discoveries about motion in the heavens.

He also brought together the Baconian stress on generating laws by inductive arguing from experience and Descartes' stress on deducing new ideas from things known well.

To do this Newton had to invent calculus.

Newton provided an explanation for heavenly motion that was tied to observed properties of motion on Earth. (Galileo + Kepler)

And he geneneralised laws from these observations, but based laws based on mathematics. Newton had read Descartes and in fact attacked him, but uses his mathamatical appraoch. (Bacon + Descartes)

A Better Synthesis than Aristotle

So at last there was a synthesis better than that provided by Aristotle. Newton accounted for motion throughout the Universe.

Newton also had to attack Descartes view on a plenum of matter, with vortices moving the planets.

Newton's explanation was based on idea of Inertial Movement and Gravity.

All bodies moved as if every particle attracted every other particle with a force proportional to the product of the two masses and inversely proportional to the square of the distance between them.

NOTE THAT THIS IS NEVER THE CASE IN THE REAL WORLD. NEWTON'S GENIUS WAS TO IMAGINE MOTION OUTSIDE THE REAL WORLD OF IMPEDIMENTS TO MOTION, AND A WORLD OF VERY MANY PARTICLES, AND TO IMAGINE A UNIVERSE WITH ONLY TWO PARTICLES, BUT TO BASE THAT IMAGINATION ON OBSERVATION.

(Eg. in 1672 Jean Picard, a Frenchman observed Mars from Paris and Cayenne, and worked out its altitude. This helped Newton in his calculations.)

He still could not explain Gravity.

Newton still had room for God; and he was very pious .

The Three Laws of Motion

Note that motion is normal, and does not need explaining. Also force can be conveyed without physical touching. It is still not clear if Newton was correct here.

Inertia drives out the angels and lets us get the view of the Universe a a large piece of clockwork.

Newton also worked on Optics - Opticks - 1704

Newton was not, of course, "right". Einstein and Quantum Mechanics in the last century have shown that, but his model was infinitely better than anything done before.

Alexander Pope

Nature and nature's laws lay hid in night;
God said, "Let Newton be." and all was light.

VIII. Other Sciences

A. Other Sciences than Physics and Astronomy

Other sciences were less on the cutting edge. They were less mathematical, but do exhibit a can-do attitude.

Chemistry did not show advances until a century later.

B. The Development of Instrumentation

-Clocks

-Galileo and Telescope

-Leeuwenheok - microscope

IX. Medicine

We saw it made little practical progress until late 1700s.

In Theory it carried a lot of baggage: the demonic view of illness.

The influence of Galen (2nd Cent. AD).

A. Vesalius

A doctor at Padua. In 1543 he began investigating anatomy.

B. William Harvey

Had studies at Padua.

1628 - On the Movement of the Heart and the Blood

Harvey explained notion of continual circulation of the blood. (da Vinci had know this but not published a century earlier).

C. Malpighi (Italian)

1661 discovered Capillaries

X. Practical Effects of the Scientific Revolution

There were few practical effects on technology. It is important to realize that the Industrial Revolution did not at first depend on this new scientific view of the world.

But new maths and science did effect navigation, map making and artillery.

-Better guns were another way Europeans came to dominate the world; they had better ways of using weapons and better ways of knowing where they were.

-Also the laws Newton discovered could be used to fire more accurately. This effect was felt soon after Newton.

- Science has innumerable practical ramifications: new guns, bigger armies, more taxes, social discontent.

XI. A New Attitude

A. Attitude to Past

With Newton modern civilization did something the ancients had not been able to do. It explained motion and the heavens.

There was now a sense of skepticism about beliefs held on old authority.

B. The Powers of Reason

This led to a new confidence in the powers of reason, and perhaps a move away from faith, even if it was not rejected.

We shall be moving on to the Enlightenment proper, which built especially on Newton in next class.

C. Natural Law

But note that old attitude of seeing a NATURAL LAW at work in Universe was confirmed in the new Newtonian world view.

D. Can-do approach

A can do-approach and the idea of progress had a part in the Industrial Revolution.

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