Key Ideas

-- The details of thermal radiation from an object -- blackbody radiation -- cannot be explained by classical Physics; unusual and unexpected assumptions are required.

-- To explain the details of light striking a metal and releasing an electron -- the photoelectric effect -- requires that light be treated as a stream of particles.

-- Electrons have a wave nature. Their wavelength, often called the deBroglie wavelength, depends upon their momentum.

-- To explain some experiments, we must describe light or electrons as waves, whereas to explain other experiments, we must describe light or electrons as particles. This is known as the complementarity principle.

-- The momentum and position of an object cannot both be known with arbitrary accuracy. Measuring one more accurately increases the uncertainty in the other. This is known as the Heisenberg undertainty principle.

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(c) Doug Davis, 2002; all rights reserved