Three of the greatest western physical scientists ever known, Isaac Newton, Thomas Young and Albert Einstein were much distracted by the question ‘What exactly is light’.
Newton rhetorically asks ‘Are not the rays of light very small bodies emitting from shining substances?’ He had essentially developed a corpuscular or particle model of light, coming to this conclusion partly from the observation that light is split into two beams by certain transparent crystals. Some 100 years later Thomas Young undertook his famous experiment ‘Young’s double slit’ concluding that a wave model for light is more suitable.
Another century passes before Albert Einstein, in explaining the photoelectric effect, reinforced a particle (quantum) model of light. But who is actually correct?
Light illustrates the extraordinary wave-particle duality of the Universe. Newton, Young and Einstein were all right to some measure.
This demonstration lecture will explore some aspects of light and wave-particle duality.