Thursday, January 31, 2013

Quiz


  1. How did Copernicus, Tycho, and Kepler challenge the Earth centered model?
  2. What are Kepler's three laws of planetary motion?
  3. How did Galileo solidify the Copernican revolution?
  4. How can we distinguish science from nonscience?
  5. What is a scientific theory?
  6. In what sense is the moon imperfect?
  7. Why did Kepler use ellipses instead of circles?
  8. When was Tycho Brahe born?
  9. When was Johannes Kepler born?
  10. When was Galileo Galilei born?

Chapter 3.4 Notes


Chapter 3.4 Notes

How can we distinguish science from nonscience?
·         Defining science can be surprisingly difficult.
·         Science comes from the latin scientia, meaning knowledge.
Hallmarks of science #2
·         Science progressed through the creation and testing of models of nature that explain the observations.
Hallmarks of science #3
·         A scientific model must make testable predictions about natural phenomena that would force us to revise or abandon the model if the predictions do not agree wit observations.
What is a scientific theory?
·         The word theory has a different meaning in science than in everyday life.
·         In science, a theory is not the same as a hypothesis
·         A scientific theory must:
Explain a wide variety of observations with a few similar principles.
Be supported by a large, compelling body of evidence.
NOT have failed any crucial test of its validity.

Chapter 3.3 Notes continued


How did Galileo solidify the Copernican revolution
·         Galileo (1564-1642) overcame major objections to the Copernican view. Three key objectives rooted in the Aristotelian:
Earth could not be moving because objects in air would be left behind.
Noncircular orbits are not perfect as heavens should be.
If earth were really orbiting sun, we’d detect stellar parallax.
Overcoming the first objection
·         Galileos experiments showed that objects in air would stay with a moving earth.
Aristotle thought that all objects naturally come to rest.
Galileo showed that objects will stay in motion unless a force acts to slow them down (Newtons first law of motion)
Overcoming the second objection
·         Tychos observations of comet and supernova already challenged this idea.
·         Using his telescope, Galileo saw:
Sunspots on the sun.
Mountains and valleys on the moon (proving it is not a perfect sphere).
Overcoming the third objection
·         Tycho thought he had measured stellar distances, so lack of parallax seemed to rule
out an orbiting earth.
·         Galileo showed stars must be much farther than tycho thought—in part by using his telescope to see that the Milky Way is countless individual stars.
·         I stars were much farther away, and then lack of detectable parallax was no longer so troubling.
·         Galileo also saw four moons orbiting Jupiter, proving that not all objects orbit earth.
·         Galileo’s observations of phases of Venus proved that it orbits the sun and not earth.
·         In 1633 the Catholic Church ordered Galileo to recant his claim that earth orbits the sun.
·         His book on the subject was removed from the church’s index of banned books in 1824.
·         Galileo was formally vindicated by the church in 1992.

Wednesday, January 30, 2013

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Chapter 3.3 Notes



Chapter 3.3 Notes

How did Copernicus, tycho, and kepler challenge the earth centered idea?
·        Copernicus proposed the sun centered model.
·        He used the model to determine the layout of the solar system.
·        Tycho compiled the most accurate naked eye measurements ever made of planetary positions
·        He still could not detect stellar parallax, and thus still thought earth must be at the center of the solar system.
·        He hired keplar who used tychos observations to discover the truth about planetary motion.
·        Keplar first tried to match tychos observations with circular orbits.
·        But an 8 arcminute discrepancy led him eventually to ellipses.

Chapter 3.2 Notes



Chapter 3.2 Notes

Why does modern science trace its roots to the Greeks?
·        Our mathematical and scientific heritage originated with the civilizations of the middle east
·        Greeks were the first people known to make models of nature.
·        They tried to explain patterns in nature without resorting to myth or the supernatural.
How did the greeks explain planetary motion?
·        Earth at the center of the universe
·        Heavens must be “perfect”--- objects move on perfect spheres or in perfect circles.
·        The most sophisticated geocentric model was that of Ptolemy.
·        The Ptolemaic model had each planet move on a small circle whose center moves around earth on a larger circle.
How did Islamic scientists preserve and extend greek science?
·        The muslim world preserved and enhanced the knowledge they received from the greeks while Europe was in its dark ages.
·        Al-Mamuns house of wisdom in Baghdad was a great center of learning around AD 800
·        With the fall of Constantinople in 1453, eastern scholars headed west to Europe, carrying knowledge that helped ignite the European renaissance.
·        Islamic scientists archived and improved on greek learning. Their knowledge was eventually carried back to Europe, helping to ignite the European renaissance.

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Chapter 3.1 Notes



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In what ways do all humans employ scientific thinking?
·        Scientific thinking is based on everyday ideas of observation and trial and error experiments.
How did astronomical observations benefit ancient socities?
·        In keeping track of time and season
For practical purposes, including agriculture
For religious and ceremonial purposes
·        In aiding navigation
·        Ancient people of central Africa could predict seasons from the orientation of the crescent moon.
·        Keeping track of time and seasons; navigation
What did ancient civilizations achieve in astronomy?
·        Daily timekeeping
·        Tracking the seasons and calendar
·        Monitoring lunar cycles
·        Monitoring planets and stars
·        Predicting eclipses
·        Egyptian obelisk: shadows tell time of day.