Let There Be Light

1
Let There Be Light!

• Dr. Alain Brizard
• Department of Physics
• Saint Michaels College
• First Year Seminar
• February 5, 2001

2

• Nature and
• Natures Laws
• lay hid in the Night
• God said
• Let Newton be
• and all was Light.
• Alexander Pope

3
The Universe

• Should we contemplate or investigate the
  Universe?
• What are Planets?
• Cosmic Wanderers
• Keplers Harmonice Mundi

4
Music of the Spheres

• Mysteries do not lose
  their poetry when solved.
• The solution often turns out more beautiful
  than the puzzle and, in any case,
  when you solve one mystery,
• you uncover others,
  perhaps to inspire greater
  poetry.

5
Light and Matter

• Light interacts with matter in 3 steps
• Light is absorbed by an atom, which becomes
  excited
• The atom remains excited for a finite amount of
  time and
• The atom returns to its ground state by
  re-emitting light (with some energy loss).
• Light slows down when it enters matter.

6
Principle of Least Action

• Light obeys the Principle of Least Time.
• http//www.explorescience.com/activities/Activity_
  page.cfm?ActivityID53
• http//www.phy.ntnu.edu.tw/hwang/Fermat/Fermat.ht
  ml
• Matter obeys the Principle of Least Action.
• The mystery of the Principle of Least Action is
  lifted by Quantum Physics.

7
Beauty of the Rainbow

• Refraction and Color Dispersion
• http//www.explorescience.com/activities/Activity_
  page.cfm?ActivityID51
• Internal Reflection and Rainbows
• http//www.phy.ntnu.edu.tw/java/Rainbow/rainbow.ht
  ml

8
Color Vision

• Human vision
• http//www.adobe.com/support/techguides/color/colo
  rtheory/vision.html
• Red-Green-Blue
• http//phys.educ.ksu.edu/vqm/java/colorcreator/vqs
  cp.html

9
How do we Look in the Dark?

• Electromagnetic Spectrum
• Blackbody radiation versus temperature
• http//www.phy.duke.edu/peh/physlets/physlet2.htm
  l

10
Chemical Bar Code

• Absorption spectrum
• http//phys.educ.ksu.edu/vqm/html/absorption.html
• Emission spectrum
• http//home.achilles.net/jtalbot/data/elements/in
  dex.html
• http//phys.educ.ksu.edu/vqm/html/emission.html

11
Encoded Rainbow

• Solar spectrum
• http//www.isp.nwu.edu/smithers/black.html

12
Twinkle, Twinkle, Little Star!

• Radiation from the Stars
• http//www.astro.lsa.umich.edu/users/hughes/Kircho
  ff/Kirchoff.html
• Stellar temperature
• http//www.astro.ubc.ca/scharein/a310/Sim.html -
  Blackbody

13
The Birth and Death of Stars
14
Doppler Effect

• Doppler effect
• http//www.astro.ubc.ca/scharein/a310/Sim.html -
  Doppler
• Why stars wobble
• http//instruct1.cit.cornell.edu/courses/astro101/
  java/binary/binary.htm
• http//www.astro.ubc.ca/scharein/a310/Sim.html -
  xtrasol

15
Receding Light

• Hubbles Law
• http//msowww.anu.edu.au/2dFGRS/Public/Pics/2dFzco
  ne.gif

16
Light from the Edge

• Blackbody radiation from the Universe
• COBE
• http//origins.jpl.nasa.gov/library/kona/06_Galaxi
  es.html

17
The Day Light Escaped Matter
18
The Big Picture

• Physics at the
• largest scales
• Physics at the
• smallest scales

19
Truth and Beauty

• The shuddering before the beautiful, this
  incredible fact
• that a discovery by a search after the beautiful
  in
• mathematics should find its exact replica in
  Nature,
• persuades me to say that beauty is that which the
  human
• mind responds at its deepest and most profound.