Fun video for the ABC, doing my best to explain what light is – but in a single elevator ride.
As a side note, this is a textbook example of an insufficient explanation for the particle nature of light! (But how to do it in just a fraction of an elevator ride!!!???) As my quantum photonics friends keep telling me, I am cheating by assuming I know the answer. For anyone interested in this fascinating topic, I recommend getting your hands on first few chapters of this wonderful book:
The Quantum Challenge: Modern Research on the Foundations of Quantum Mechanics, by George Greenstein and Arthur G. Zajonc (Jones and Bartlett, 2006)