Generally speaking, there are three criteria that X projects share.
All must address a problem that affects millions–or better yet, billions–of people.
All must utilize a radical solution that has at least a component that resembles science fiction.
And all must tap technologies that are now (or very nearly) obtainable.
via The Truth About Google X: An Exclusive Look Behind The Secretive Lab’s Closed Doors | Fast Company | Business + Innovation.