Half life has an easy answer... what's the definition?:confused:

Half-life is the length of time that it takes for 1/2 of a decomposable material (often a radioactive material) to decompose.

Half-life - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Half-life)

Let me google that for you: half-life (http://www.lmgtfy.com/?q=half-life)