In the late 1990s, two teams of astronomers stunned the scientific community with the finding that the universe is accelerating in its expansion, somehow overpowering the constant pull of gravity that should be slowing it down. The culprit pressing the cosmic accelerator goes by the name "dark energy," which is an appropriately enigmatic moniker for something that remains so poorly understood.
"We have an amazingly simple picture of the universe," says Princeton University astrophysicist Michael Strauss. "Of course, we don't understand that picture—we don't know what dark energy is, and we don't know what dark matter is." Dark matter, a mysterious entity of longer standing, is some invisible but common substance that reveals itself only through its gravitational pull.
"This is good news for my theory." -- Jack Sarfatti