concepts in sci (winter)

• phi is defined to be the ratio obtained by dividing a line segment into two unequal pieces such that the entire segment is to the longer piece as the longer piece is to the shorter
• if the atoms in the molecule do not move too far, the force between them can be modelled as if there were springs between the atoms.
• the potential energy acts similar to that of SHM oscillator
• in studying vibrations it is advisable to begin with the simplest type: a one dimensional vibration that has only a single frequency component= (pure tone)
• where are we in the universe:

  planet earth

  solar system

  milky way galaxy

  local group

  local supercluster

  universe
• The Earth is a planet in the solar system consisting of objects orbiting the star sun
• the solar system is part of a galaxy called the milky way
• the milky way is part of a group of 40 galaxies called the local group
• the local group belongs to the local supercluster (also called Virgo supercluster)
• the 3-dimensional distribution of luminous matter has a "soap-bubble" appearance
• the visible galaxies mostly on the surface of the "soap bubbles"
• the superclusters appear as elongated strands where different soap bubbles come together.
• the clusters appear as bright spots on the strands corresponding to the superclusters
• the soap bubbles around large voids of approximately 150 million ly size that contain little easily seen matter
• Scientific thinking is based on everyday ideas of observation and trial-and-error experiments.
• astronomical observations benefit ancient societies

  • Keeping track of time and seasons
  • for practical purposes, including agriculture
  • for religious and ceremonial purposes
• astronomical observations benefit ancient societies

  • Aid to navigation
• Modern science traces its roots to the Greeks
• Islamic scientists preserved and extended Greek science
• So far astronomy only involved making observations, recognizing basic patterns and making rudimentary predictions
• A crucial part of the scientific method - building models/hypotheses that did not resort to supernatural or godly influence - was missing
• Greeks were the first people known to make models ofnature
• Thales of Miletus first assumed that the world was understandable and proposed a model of the earth. He successfully predicted a solar eclipse
• Pythagoras suggests that the Earth is a sphere and not flat, as had been previously assumed
• Earth's curvature visible over 13 mile distance.
• When traveling north, new stars appeared above northern horizon, while stars previously seen along southern horizon no longer visible; reverse true traveling south
• Circular shadow projected by Earth when it eclipses the Moon
• Eratosthenes measures the earth
• Simple geocentric models make it difficult to explain apparent retrograde motion of planets
• The modern heliocentric model easily explains apparent retrograde motion of planets
• How did the Greeks explain planetary motion?

  Heavens must be “perfect” : objects moving on perfect spheres or in perfect circles.
• Ptolemaic system, a mathematical model of the universe formulated by the Alexandrian astronomer and mathematician Ptolemy about 150 CE and recorded by him in his Almagest and Planetary Hypotheses. 
• the Ptolemaic model is sufficiently accurate to remain in use for 1,500 years
• the ordered universe is predictable and quantifiable
• Without the predictability of physical events, the scientific method could not proceed.
• Galileo saw four moons orbiting Jupiter, proving that not all objects orbit the Earth
• Galileo's observations of phases of Venus proved that itorbits the Sun and not Earth
• Experimentation

  • collecting data using instruments and mathematical calculations
• Science from the Latin scientia, meaning “knowledge.”

  • But not all knowledge comes from science
• The Scientific Method is a “process”

  • Identifying patterns
  • Hypothesis
  • Prediction
  • Experimentation (Observation)
  • Identifying patterns