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The Scientific Revolution in the 17th Century

From Aristotle to Newton

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Aristotle (384 - 322 B.C.)

• known as "the Philosopher" by later thinkers, created a huge body of work that was virtually synonymous with philosophy for over 2000 years.

• "perplexed with obscure terms and useless questions" John Lock (1632–1704)

• "a naive and childlike animistic view of the world." Jean Piaget (1896-1980)

• “The greatest philosopher of all times”– Modern attitude to Aristotle

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Aristotle's cosmology

• Geocentric• Crystal spheres• Dualist• Sublunary world is

imperfect• Beyond the moon

the world is perfect, unchangeable and eternal

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Aristotle's cosmology I

• Sun and planets were attached to crystal spheres revolving around the Earth.

• All motions beyond the moon were perfectly circular.

• Gravitation was a phenomenon applying to the Earth only, as an expression for things seeking their natural place

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Aristotle's cosmology II. • A organized and classified an immense

amount of knowledge, much of it scientific theories developed with only the crudest observational tools.

• All knowledge is organized into the theoretical disciplines (physics, "first philosophy" [metaphysics], and math); practical disciplines (ethics and politics); and productive disciplines (engineering, medicine, etc.).

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Aristotle's cosmology III.

• He classified four types of change (generation / corruption, increase / decrease, alteration, and locomotion)

• and four types of causation (the material, the formal, the initiating force, and the goal).

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Aristotle's cosmology IV.• Aristotle formed a metaphysical theory of what is

real ("substance"), and described the idea that all things have "potential" and "actual" characteristics.

• He created logic to distinguish correct from incorrect reasoning; and

• he reasoned that all motion ultimately is caused by an immutable perfection, an unmoved "primer mover" - which Aristotle called "God."

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Claudius Ptolemy• Egyptian living in

Alexandria, at about 150 A.D., gathered and organized the thoughts of the earlier thinkers - Almagest

• Created a geocentric cosmology based on mathematics and observation

• A perfect circle was the only possibility for movement in the sky

• No physics in his model

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Eccentric, epicycle, equant

eccentric

epicycle

equant

CombinedEquant andepicycle

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Nicolas Copernicus (1473-1543)

• Could not accept the complexity of Ptolemy’s theory nor that could exist two different theories.

• 1543 De Revolutionibus Orbium Caelestium (On the Revolution of the Heavenly Orbs).

• Heliocentric world view!

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Copernicus cosmology

• Mostly the Aristotelian model where Copernicus places the sun in the middle instead of the earth

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The Problems of Copernicus

• If the earth is moving, why do things not fly away?

• The parallax

• The orbits of his theory did not fit with observations– He still had to use epicycles...

• Why did the moon circle around the earth?

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The parallax

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Tycho Brahe (1546-1601)

• Denmark's hottest stargazer

• Refined the tools and equipment for the observation of the heavenly bodies

• 1572-73 Crab Nebula

• 1577 new comet – Crashed the crystal spheres

• Alternative cosmology

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Brahes astronomy

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Johannes Kepler (1571-1630)

• Three Laws of Planetary Motion

• Solved many of the problems of Copernicus

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Kepler's Laws of Planetary Motion

• The First Law:– Planets move in ellipses with the Sun at one focus.

• The Second Law: – The radius vector describes equal areas in equal times

• The Third Law:– The squares of the periodic times are to each other as

the cubes of the mean distances

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Circular and Elliptical Orbits Having the Same Period and Focus

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Galileo Galilei (1564-1642)

• 1600 Giordano Bruno burnt

• 1601-1610 The Telescope• 1615 Letter to Grand

Duchess of Tuscany • 1632 Dialogue on Two

World Systems • 1633 Galileo banned by

the Church • 1638 Discourse on Two

New Sciences

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Galileo’s contributions

• Heliocentric cosmology of Copernicus• Critics of Aristotle's theory of motion• Pendulum• Through the telescope Galileo saw

– The mountains of the moon, discovered the four satellites of Jupiter, observed a supernova, verified the phases of Venus, and discovered sunspots.

– His discoveries proved the Copernican system which states that the earth and other planets revolve around the sun.

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Galileo's telescope (1601)

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Galileo and the Inquisition

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Francis Bacon (1561-1625)

• 1620 Novum Organum (New Tools)

• Theory of Induction• Empiricist• The gunpowder and the

compass have 'changed the whole face and state of things throughout the world‘, there will be more of such things in the future.

• Through science we will master nature.

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Bacon/Novum Organum

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Descartes/

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Rene Descartes (1596-1650)

• 1637 Discourse on Method • Theory of Deduction• Abandoned the Copernican theory• In its place he devised a theory of

vortices in which space was entirely filled with matter, in various states, whirling about the sun.

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Descartes...

• Pure mechanistic cosmology• Vacuum does not exist• Optics

– Discovered of the fundamental law of reflection: that the angle of incidence is equal to the angle of reflection

– Descartes' treatment of light as a type of pressure in a solid medium paved the way for the undulatory theory of light

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Isaac Newton (1642-1727)

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Isaac Newton two main contributions

• 1687 Philosophiae Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy)

• Opticks - 1704

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Newton's Three Laws of Motion

1. A body moves in a straight line unless impeded. (Inertia).

2. Every action has equal and opposite reaction.

3. Every body attracts every other body with a force proportional to the distance between.

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Newton's theory of gravitation

• Newton proposed his law of gravitation in 1687 and stated that every particle in the universe attracts every other particle in the universe with a force that depends on the product of the two particles' masses divided by the square of the distance between them

• Universal law - same physics in heaven as on earth

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Newton and the apple

• Dealing with the apple and the satellite solve the problem of gravity and connect heaven and earth in the same physics!

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Anatomy and Medicine

• Hippocrates (ca. 460-377 B.C.) He also gave the world the Hippocratic Oath, a code of ethics for physicians which is still taken by graduates at many modern medical schools. The Hippocratic Oath

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Hippocrates

• Perhaps history's most famous physician.– By rejecting superstition in favor of scientific

observation, – By classifying diseases, – By creating a set of moral and professional

standards for physicians, – He earned the title of 'Father of Medicine.'

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The Hippocratic biophysics

air fire earth water Hot and wet blood heart spring sweet boy snguine

Hot and dry Yellow bile liver, stomach sumer bitter youngster quick-tempered

Cold and dry Black bile spleen autum sour adult melancholic

Cold and Wet phlegm urinary bladder winter salt old man phlegmatic

• The elaborate general doctrine of the Four Humors endured through many centuries and is central to the tenets of the Hippocratic Corpus:

– The elaborate general doctrine of the Four Humors endured through many centuries and is central to the tenets of the Hippocratic Corpus. It was grounded on the Empedoclean principle of the four supposed elements: earth, air, fire and water.

– The four constituent elements, or humors, in man were identified analogously as phlegm, blood, yellow bile and black bile, all of which had to be in correct proportion

to one another.

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Erasistratus of Ceos (c.250 BC)

• Greek physician, born in Ceos. – He founded a school of

anatomy at Alexandria

– Considered one of the pioneers of modern medicine.

– He is said to have been the first to trace arteries and veins to the heart, and to have named the tricuspid valve in the heart.

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Galenos (131-201 a.d.) • Greek physician.

– He studied medicine at Pergamum, Smyrna, Corinth, and Alexandria, and later lived in Rome.

– He was a voluminous writer on medical and philosophical subjects, and gathered up all the medical knowledge of his time, thus becoming the authority used by subsequent Greek and Roman medical writers.

• The authority for 1500 years.

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Vesalius (1514–64)

• Advanced dissection of the human body

• De humani corporis fabrica libri septem (1543, Seven Books on the Structure of the Human Body)

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William Harvey (1578–1657)

• De motu cordis et sanguinis in animalibus (On the Motion of the Heart and Blood in Animals), in which the circulation of the blood was first described, was published in 1628.

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Malpighi(1628–94) Pisa

• The founder of microscopic anatomy, he described the major types of plant and animal structures

• Capillaries 1661