The Scientific Revolution The Scientific Revolution 15th to the by ewghwehws


									The Scientific Revolution
   15th to the 17th Centuries
Medieval Reliance on Classical
• Medieval scholars had used the Latin
    translations of Aristotle, Galen, and Ptolemy to
    develop many of their positions in the fields of
    physics, medicine and astronomy
•   As a result of their reliance upon a few ancient
    authorities, plus the subjection to a strict
    theological framework, medieval scientists,
    also known as “natural philosophers” were
    limited in where they could go
•   In fact, many preferred refined logical analysis
    to systematic observations of the natural world
Renaissance Scholarship and
Classical Disagreements
•   This view began to be challenged with the emergence
    of the Renaissance
•   Renaissance humanists mastered not only Latin, but
    also Greek which made available to them new writings
    of Galen, Ptolemy, and Archimedes but also Plato and
    the pre-Socratics
•   This led humanists to recognize that the unquestioned
    authorities of the Middle Ages, Aristotle and Galen, had
    been contradicted by other thinkers
•   This stimulated the desire to discover which school of
    thought was the correct one with the result sometimes
    leading to the complete rejection of the classical
Artists and Close Observation of
•   Renaissance artists have been also credited with
    making an impact upon scientific study - desire to
    imitate nature led them to rely on a close observation
    of nature
•   With their accurate renderings of rocks, plants,
    animals, and human anatomy, they established new
    standards for the study of natural phenomena
•   Moreover, the “scientific” study of the problems of
    perspective and correct anatomical proportions led to
    new insights as a Renaissance artist declared, “No
    painter can paint well without a thorough knowledge
    of geometry.”
Early Modern Technological
•   The solving of technical problems also stimulated the
    growth of scientific knowledge
•   Relationship between technology and the Scientific
•   Many of the technical innovations of the period were
    accomplished outside the universities by people who
    placed an emphasis upon practical and not theoretical
•   Either way, the invention of new instruments and
    machines, for example the microscope and the
    telescope, made new scientific discoveries possible
The New Mathematics
•   Rediscovery during the Renaissance of the works of
    ancient mathematicians and the influence of Plato
•   While mathematics was seen as the key to navigation,
    military science, and geography, there was also a
    widespread belief during the Renaissance that
    mathematics was the key to understanding the nature
    of things
•   Many of the great minds of the period, Copernicus,
    Kepler, Galileo, and Newton, who were all
    mathematicians, believed that the secrets of nature
    were written in the language of mathematics
•   Lastly, mathematical reasoning was seen as promoting
    a degree of certainty that was otherwise impossible
Toward a New Heaven:
A Revolution in Astronomy
•       Cosmology of the Middle
    –     Mix of Aristotle, Ptolemy
          and Christian theology
•       Geocentric Model
    –     Earth center of the
          universe; motionless
    –     Surrounded by series of
          eight concentric spheres
    –     Spheres moved around
          the Earth in circular
          motion – most perfect
    –     Finite structure
Copernicus (1473-1543)
•       On the Revolutions of the Heavenly Spheres
    –     Written between 1506 and 1530
    –     Argued that universe was heliocentric
•       Heliocentric Model
    –     Argued that the universe consisted of eight spheres with the
          sun motionless at the center
    –     Moreover, the movement of the sun and fixed stars was
          really explained by the daily rotation of the Earth on its axis
          and the journey of the earth around the sun each year
    –     However, Copernicus was basically conservative and he did
          not reject the notion of heavenly spheres moving in circular
          orbits - therefore, his system was just as complicated as
•       Church Reaction to Copernicus
Tycho Brahe (1546-1601)
•   Danish nobleman
•   He spent 20 years observing the positions
    and movements of the stars and planets from
    his observatory
•   This body of work led him to reject the
    Aristotle-Ptolemaic system, but he could not
    accept Copernicus’ suggestion that the Earth
•   Spent last years in Prague as imperial
    mathematician to Rudolf II where he took an
    assistant by the name of Johannes Kepler
Johannes Kepler (1571-1630)
•   Destined to be a Lutheran
    minister, but followed his true
    interest of mathematics and
•   Became assistant to Brahe
    and replaced him as imperial
    mathematician upon his death
•   With access to Brahe’s
    detailed astronomical data
    Kepler arrived at his three
    laws of planetary motion
    which confirmed Copernicus’
    heliocentric theory, though
    modifying it in some ways
Johannes Kepler (1571-1630)
• Kepler’s Three Laws
   – First two were published in 1609
   – First Law rejected Copernicus to an extant because Kepler
     showed that the orbits of the planets were elliptical, not circular
   – Second Law stated that the speed of a planet is greater when it
     is closer to the sun
   – Third Law in 1619 – established that planets with larger orbits
     revolve at a slower average velocity than those with smaller
• Result of Kepler’s Three Laws
• However, questions still remained – What were the
  planets made of and how does one explain motion in the
Galileo Galileo (1564-1642)
• First European to make systematic
    observations of the heavens by means of a
    telescope and thus inaugurated a new age in
•   What he saw through the telescope
•   His observations destroyed another aspect of
    traditional cosmology - the universe was
    composed of material substance similar to that
    of Earth
Galileo Galileo (1564-1642)
• The Starry Messenger
  – Published in 1610
  – Stunned contemporaries and did more to make
    Europe aware of the new picture of the universe than
    the mathematical theories of Copernicus and Kepler
• Galileo, the Church and Inquisition
• Dialogue on the Two Chief World Systems:
  Ptolemaic & Copernican
• Placed under house arrest and during his final
  eight years Galileo studied mechanics
  discovering the principles of inertia & force
Isaac Newton and Universal Physics

• One of the most talented minds of his age
• The Law of Universal Gravitation
  –   Principia (1684-86)
  –   Greatest work in which he spelled out the
      mathematical proofs of the Law of Universal
  –   Culmination of the theories of Copernicus, Kepler,
      and Galileo piecing together a coherent synthesis
      for the new cosmology
• Three Laws of Motion
• Universal Law of Gravity
Isaac Newton and Universal Physics

• The implications of Newton’s law were enormous
    for he demonstrated with one universal law,
    mathematically proved, that all motion in the
    universe, from the movements of the planets to
    an apple falling off a tree, could be explained
•   This Newtonian synthesis created a new
    cosmology in which the world was largely seen
    in mechanistic terms
•   Would remain the dominant cosmology until
    Einstein’s concept of relativity
Advances in Medicine:
Influence of Galen
•   Greek physician from 2nd century AD
•   Had great affect on medieval medical world
•   Relied on animal, rather than human dissection, to
    gain picture of human anatomy
•   Study of anatomy in the Middle Ages still relied upon
•   Additionally, treatment of disease was still based
    upon Galen’s doctrine of four bodily humors – blood,
    yellow bile, phlegm, and black bile
•   The works of three men challenged the doctrine of
    Galen and generally replaced it by the 17th century
Paracelsus (1493-1541)
•   Rejected the work of both Aristotle and Galen
•   Replace the traditional system with a new chemical
    philosophy based upon a new understanding of nature
    derived from fresh observation & experiment
•   Believed disease was caused by chemical imbalance in
    the organs which could be solved by chemical
•   Although chemical remedies had been used,
    Paracelsus and his followers differed by giving careful
    attention to the proper dosages of their chemically
    prepared metals & materials
Andreas Vesalius (1514-1564)
•       His studies corrected Galen in relation to anatomy -
        believed practical research as the best way for
        understanding human anatomy
•       1543 published On the Fabric of the Human Body
    –      Based upon his lectures at Padua
    –      Deviated from traditional practice by personally dissecting a
           body to illustrate what he was discussing
•       Through his “hands-on” approach, Vesalius rectified
        some of Galen’s more glaring errors
•       For example, the belief that the great blood vessels
        originated from the liver, but he still clung to Galen’s
        belief about the ebb & flow of two kinds of blood in
        the veins and arteries
William Harvey and the Human
Blood System
• It was only with the discoveries of William
    Harvey that this belief was corrected
•   Through his research & observations, Harvey
    demonstrated that the heart, not the liver, was
    the beginning point of circulation of blood in
    the body, that the same blood flows in both
    veins and arteries, and most important, blood
    makes a complete circuit as it passes through
    the body
René Descartes (1596-1650)
•   The fundamentally new conception of the universe was
    bound to have an impact upon the Western view of
•   Nowhere is this more apparent than in the works of
    Rene Descartes whose philosophical system would
    dominate Western thought until the 20th century
•   He set out his philosophical system in his book
    Discourse on Method
•   Descartes decided to set aside all that he had learned
    and begin again, though one fact above all seemed
    beyond doubt to him – his own existence, “I think,
    therefore I am”
René Descartes (1596-1650)
• With this emphasis upon the mind, Descartes asserted
  that we could accept only those things which our reason
  said were true
• Moreover, from this first postulate Descartes deduced a
  second principle, the separation of mind & matter
• Matter now became something totally separate and
  could now be investigated independently by reason
• Additionally, this split would have major implications not
  just for traditional religious views of the universe, but
  also how Westerners saw themselves
The Scientific Method
•   In the course of the Scientific Revolution,
    attention was also paid to the problem of
    establishing the correct means to examine
    and understand the physical realm
•   Therefore, the development of a scientific
    method was crucial to the evolution of
    science in the modern world
The Scientific Method
• Francis Bacon
  – Englishman with few scientific credentials
  – Devised a system or scientific method that was built
    on inductive principles
• Rene Descartes’ Emphasis on Deduction and
  – Conversely, Descartes argued for an approach that
    emphasized deduction and mathematical logic
  – He believed that one could start with self-evident
    truths, comparable to geometrical axioms, and
    deduce more complex conclusions
Isaac Newton’s Synthesis of Bacon
and Descartes
• Isaac Newton then synthesized these two
    systems into a simple scientific methodology
    uniting Bacon’s empiricism with Descartes’
•   This scientific method began with systematic
    observations and experiments, which were then
    used to arrive at general concepts
•   New deductions derived from these general
    concepts could then be tested and verified by
    precise instruments

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