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  Don’t forget that light travels
faster than sound . . . that’s why
 so many people appear bright
         until they speak.
       Particle or wave?
“There is no knowledge, no LIGHT, no
  wisdom that you are in possession of, but
  what you have received it from some
Brigham Young
1801-1877, American Mormon Leader
       Particle or wave?
• Light is a particle (“corpuscular”) !
  – Newton
• Light is a wave!
  – Huygens
• Max Planck, 1900:
  – How does emitted radiation relate to temp?
  – Mathematical “fudge factor”
     • Assumed energy (I.e., temperature) was chunked,
       discrete, not a continuous function
. . . and there is light.
       Light production
But, soft! what light through yonder
  window breaks? It is the east, and Juliet
  is the sun. Arise, fair sun, and kill the
  envious moon, Who is already sick and
  pale with grief, That thou her maid art
  far more fair than she:
- W.Shakespeare, Romeo and Juliet
. . . and there is light.
       Light production
• Bohr model
  – Incident photon excites electron to higher
    energy level
  – Electron drops to lower energy level,
    emitting photon
  – Jump size proportional to photon energy
• Animation
• But it gets even better . . .
      stuff of Nobels
  TheThe stuff of Nobels
“An age is called Dark not because the
  LIGHT fails to shine, but because people
  refuse to see it.”
James A. Michener 1907-, American Writer
      stuff of Nobels
  TheThe stuff of Nobels
• Einstein
  – Light is quantized
  – Photoelectric effect
     Energy of emitted
      photons depended
      on frequency of
      incident light, NOT
  – Physics Nobel, 1921
• Wavicles!
“Out of compassion I destroy the
  darkness of their ignorance. From within
  them I LIGHT the lamp of wisdom and
  dispel all darkness from their lives.”
Bhagavad Gita
c. BC 400-, Sanskrit Poem Incorporated
  Into the Mahabharata
“Thy word is a lamp to my feet, and a
  LIGHT to my path.”
[Psalm 119:105]
“Thousands of candles can be lighted
  from a single candle, and the life of the
  candle will not be shortened. Happiness
  never decreases by being shared.”
 “There are two kinds of light -- the glow
  that illumines, and the glare that
JamesThurber, American author
          Mathematics . . .
"The good Christian should beware the
  mathematician and all those who make
  empty prophecies. The danger already
  exists that the mathematicians have
  made a covenant with the devil to
  darken the spirit and to confine man in
  the bonds of hell.” - St. Augustine
            Mathematics . . .
• Speed of a wave = frequency x
   c = 
• Energy of light = Planck’s constant
  x frequency
   E = h
 Planck’s constant = 6.626 x 10-34 Js
    Polarization by Transmission
Polarization by Transmission
   Polarization by Reflection
Polarization byReflection
  Polarization by Scattering
Polarization by Scattering
Dark Suckers - conceptual
• http://www.math.buffalo.ed
• A new candle has a white
  wick. You will notice that
  after the first use, the wick
  turns black, representing
  all the dark which has been
  sucked into it. If you hold a
  pencil next to the wick of
  an operating candle, the tip
  will turn black because it
  got in the path of the dark
  flowing into the candle.
         Dark Sucker “Theory”
• This intrinsic darkness is bound into the electrons
  of the surface material.
• The reason host materials get warmer as they
  release their intrinsic darkness is that there is a
  binding energy between darkness and its host
• Incidentally, the retinas of your eyes contain
  special pigments that send signals to your optic
  nerves when dark is sucked out of them —
  sucking out yellow-frequency darkness is
  experienced as seeing yellow light.
        Dark Sucker “Theory”
• Eventually, the surface can become so hot that it
  glows with incandescence, and becomes a dark
  sucker itself.
• It should be noted that objects which glow due to
  their own heat, called "blackbody radiation",
  always cool off as a result of this radiation. This
  cooling off is merely the darkness being sucked
  into the blackbody radiator (hot dark sucker) and
  making the dark sucker itself into the darkness's
  new host material.
• The darkness-to-new-host binding process
  consumes heat to form its new bonds, each of
  which has its own binding energy, and the
  blackbody gets colder as a result.
•   Chapter 14, sections 1 & 4
•   p. 523, 1-6; p. 525, #1-3;
•   p. 550+, 1-13,37-45
•   Color mixing lab

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