4.6 Percent

A fascinating illustration of how little we really know. (thx SJ)

From the NYT...

Wilkinson Microwave Anisotropy Probe. It’s a mouthful, which is why it is usually called W.M.A.P., the abbreviation for a satellite that was launched in June 2001 and retired this September.

It is hard to overstate just how far this one small satellite has carried us in our understanding of the history of the universe, its character and origin.

There are still many, many mysteries. But suddenly it was possible to say with real precision just how old the universe is — 13.75 billion years — and that it was made up of measurable percentages of things we still don’t understand: 73 percent dark energy and 22.4 dark matter. Only 4.6 percent is the ordinary kind of matter we actually know something about.