A BRIEF(?) HISTORY OF LIGHT By Phil Green

NEWTON vs …. Modern theories – Newton describes light as a tiny particle which he called a “corpuscle” (Latin for “tiny body”) – He described the different colors produced by a spectrum as different corpuscles – Explained all the known behaviors of light, i.e. reflection, refraction, color – Had to battle against other opposing theories from bitter rivals

HOOKE AND HUYGENS Robert Hooke and Christian Huygens (and others) developed wave theories of light – Also described light behaviors, but there were significant differences, especially in describing refraction – The (luminiferous) “Aether”??? – Very contentious!! Who wins? – “On The Shoulders of Giants”

OPTICKS & THE 1700’s Newton publishes OPTICKS, and “wins” the battle Not everyone is convinced (Ben Franklin) How can we prove it, one way or the other? THROUGH EXPERIMENT!!!

PROOF!!! (early 1800’s) Thomas Young and the double slit experiment (Armand Hyppolite)Fizeau and (Jean) Foucault and the speed of light in water Newton was WRONG!!!!…but…… Luminiferous Aether?? Really???.... Maybe, but could there be another explanation?

FARADAY & MAXWELL (mid-1800’s) Michael Faraday envisions “force fields” to describe electric and magnetic forces Faraday thinks that light could be disturbing those fields, but is not capable of doing the math. His young friend James Clerk Maxwell is a brilliant mathematician who develops the mathematical equations, called Maxwell’s Field Equations, describing light as an: “ELECTROMAGNETIC WAVE”

LIGHT AS A WAVE AMPLITUDE – UNITS: LUMENS, CANDELAS, CANDLEPOWER FREQUENCY (or WAVELENGTH) – SPECTRUM – COLOR (VISIBLE SPECTRUM) PIT VIPERS NIGHT VISION GOGGLES BEES

SPEED OF LIGHT- “c” 3 x 10 8 m/sOR186,000 mi/sec (in a vacuum) FASTEST THING WE KNOW OF!! (more on that later in our story….. ) HOW COULD WE MEASURE THAT? – OLAF ROEMER – FIZEAU & FOUCAULT FARADAY IS PROVEN CORRECT

UH-OH!!! CATASTROPHE STRIKES!!! MAX PLANCK TO THE RESCUE – MAC MACHINE THEORY EINSTEIN HAS AN EFFECT – LET’S GO CLUBBIN’ BOHR-ING SO NEWTON WAS RIGHT!! ……………… EXCEPT WHEN HE WAS WRONG……. 

DUAL NATURE OF LIGHT LIGHT ACTS LIKE A WAVE WHEN TRAVELLING, BUT ACTS LIKE A PARTICLE WHEN BEING ABSORBED OR EMITTED BY MATTER THIS IS THE BEGINNINGS OF QUANTUM PHYSICS