Dark matter and dark energy are (according to current theory) everpresent. However they don't appear to interact with ordinary matter except through gravity - that's how they've been discovered.
Physicists have various ideas as to what dark matter may consist of and are trying to design experiments to detect its presence, but so far it is all guesswork.
Dark energy is even more elusive, since it seems to arise from the "cosmological constant" in general relativity and probably has no physical presence as such.

• dark thoughts - krill - March 5, 2004 - 08:12 UTC
  • More dark stuff - mathman - March 5, 2004 - 22:13 UTC