Light: Heedm, see that book by Feynman that I recommended to Crab. The answer to your question is there. Actually I'll add to the list another book by the same author which also deals with it: Six Easy Pieces (also Penguin). Both books are highly readable and aimed (more or less) at the layman (although maybe not helicopter pilots!
).
Space Shuttle: By an interesting coincidence, Feynman was one of the principal members of the team that investigated the Challenger disaster.