Light have properties of both particles and waves. It is this duality of it`s nature that confused scientists of the 19th and early 20th century, when they thought light could be only a particle or a wave but not both. When the dual nature of light was finally understood, then the really interesting qualities of light (like Einstein`s theories of relativity governing matter and energy, gravity, and relative motion) began to emerge.For a very iinaccurate but simple model, think of light as a wave whose engery is so compressed that it behaves like a particlea when it can, and revertw back to wave behavior when it must.

• curved space and gravitons - fasteddy - April 27, 2002 - 20:18 UTC