FROM
http://www.npr.org/blogs/13.7/2012/03/06/148039168/dark-matter-dark-energy-and-the-shadow-universe
(...)
evocative adjective "dark," which, for astrophysicists, simply means we
can see an effect but we can't see the cause. (...) the stuff you see,
touch and experience every day — is a mere 1/20th of the cosmos.
