section 7.33 the road to newton: the law of universal gravitation
TRANSCRIPT
Section 7.33
The Road to Newton: The
Law of Universal Gravitation
Scientific Revolution: Copernicus to Galileo• Aristotelian Universe
• Geocentric• Planets revolve around
the Earth• Ptolemaic universe 200 A.D.
– Furthered Geocentric model
– Empyrean=home of the angels, immortal spirits
– Cosmos was a hierarchy of ascending perfection, heavens were purer than earth
Nicholas Copernicus• On the Revolutions of
Heavenly Orbs (1543)
• Heliocentric view
• Earth and planets revolve around the sun
• Used a mathematical construct to support
– was a little simpler than math used to explain Ptolemy's view
Brahe and Kepler• Tycho Brahe
– Studied the movement of planets: Mars
– Made vast amounts of detailed observations
Tycho Brahe's subterranean observatory on Ven, an island in the Sound between Denmark and Sweden.
• Kepler– Used the exact observations of
Brahe– Showed that Copernicus was
wrong about the perfect circular movements of planets around the sun
– Planets move in ellipses– Unified the mathematical harmony
of Copernicus and the stubborn facts of Tycho Brahe
• described the movement of the planets in explicit formulas which any competent person could verify
Kepler's model to explain the relative distances of the planets from the Sun in the Copernican System
Brahe and Kepler
Galileo (1564-1642)• Moon only reflects light and is made of
substances similar to Earth• observed its rough surface
• 1609 he built a telescope• saw spots on the sun as if the sun were
not pure planets have breadth stars do not
• Planets have satellites (Jupiter)• this verified Copernican theory• Declares that the Earth revolves around
the sun• Forced to recant his findings• Observed (from Leaning Tower of Pisa?)
that objects with different weight struck the ground at the same time
• Bodies in motion: inertia• change in motion rather than origination• dispensed with the need of an unmoved
mover
The Achievement of Newton: The Promise of Science• Why do planet not fly off in straight trajectories? • What force is involved?• Newton unified the work of Kepler and Galileo• Isaac Newton (1642-1727)
– Personally a secretive, petty, and vindictive man in daily conduct
– Drew on both Bacon and Cartesian traditions (believed that light was not mere subjective sensation but relied on math)
– Invented calculus and used a new measurement of the size of the earth
– Principia Mathematica (Mathematical principles of natural philosophy) 1687 or Principia
– Asks what kept the earth in motion and why do celestial bodies fall to the earth while the sun and moon do not?
– Kepler theorized that a force of mutual attraction existed b/t bodies but Cartesian theory rejected the absence of matter b/t to separate bodies
• Newton came w/ Universal Law of Gravity
• every particle of matter in the universe attracts every other particle with a force varying inversely as the square of the distance b/t them and directly proportional to the product of their masses
• Impact of Newton• Principia confirmed work of
Copernicus, Galileo, Kepler and heliocentrism
• Fueled a surge in science• Made a fundamental reconception
of the universe (Paradigm shift in the Weltanschauung)
Achievement of Newton: Promise of Science
Impact of Newton• His discoveries sparked the
founding of Institutionalization of knowledge
– Royal Society of London 1662– Royal Academy of Science
France 1666– Scientific periodicals and
journals• Practical applications
– Tidal movement– Timepieces (
Greenwich and the story of time John Harrison and the H4)
– Longitude• Maps
John Harrison's fourth marine timekeeper H4
• Calculus– military applications
• Improved firearms– calculus allowed an exactness to curves
and trajectories• Steam
– Boyles Law– Robert Boyle (1627-1691) used an air
pump and came up w/ Boyle’s law• under constant temperature the volume
of a gas decreases in proportion to the pressure placed on it
– Thomas Newcomen• Invented a Steam engine in 1702 with
limited application• Used by James Watt to develop steam
engine as we know it• Later Applied to government
Impact of Newton
Scientific Revolution and the world of thought• Science was called natural philosophy • Gap between Christianity and natural science
was widening• Caused a profound readjustment on human
view of himself• No longer the center of creation• Old cosmos comfortably enclosed and
ranked everything• Now humans were puny & insignificant
materials flying through endless space• Bible didn’t mention this
– Blaise Pascal, scientist and mathematicians terrified of this
• Most were optimistic
• Alexander Pope on Newton “Let Newton be and all was light”
• Human reason could conquer all• New view contributed to further secularization of European
society• Pushed religion to the side• The universe operates under natural laws• Is orderly and predictable• Contains natural rightness and justice• Ideas were more acceptable as a new view of the human
experience was emerging• Religion still strong
– Newton and Descartes wrote earnest tracts of the truth of religious doctrines
– Descartes (who questioned everything) said that the customs of one’s country were to be accepted without question
Scientific Revolution and the world of thought