'Dark energy' may mean the end of the universe

Astronomers may have unwittingly hastened the end of the Universe by simply looking at it, according to a theory reported in next Saturday's New Scientist. The novel idea is being aired by two US physicists, who attack the notion that the Universe, believed to have been created in the "Big Bang" some 13.7 billion years ago, will go on, well, forever. In fact, the poor old cosmos is in a rather delicate state, they say. Until recently, a common idea was that the energy unleashed in the Big Bang happened when a "false vacuum" - a bubble of high energy with repulsive gravity - broke down into a safe, zero-energy "ordinary" vacuum. But recent evidence has emerged that places a cosmic question-mark over this cosy thought. For one thing, cosmologists have discovered that the Universe is still expanding. And, they believe, a strange, yet-to-be-detected form of energy called dark energy pervades the Universe, which would explain why the sum of all the visible sources of energy fall way short of what should be out there. Dark energy, goes the thinking, is a result of the Big Bang and is accelerating the Universe's expansion. If so, the Universe is not in a nice, stable zero-vacuum state but simply another "false vacuum" state that may abruptly decay again - and with cataclysmic consequences. The energy shift from the decay would destroy everything in the Universe, "wiping the slate clean," says Lawrence Krauss of Case Western Reserve University in Cleveland, Ohio. The good news is: the longer the Universe survives, the better the chance that it will mature into a stable state. We are just beyond the crucial switching point, believes Krauss.

The bad news is: the quantum effect, a truly weird aspect of physics that says whenever we observe or measure something, we reset its clock. Krauss and colleague James Dent point to measurements of light from supernovae in 1998 that provided the first evidence of dark energy. These measurements may have reset the decay clock of the "false vacuum" back to zero, back before the switching point and to a time when the risk of catastrophic decay was greater than now, say Dent and Krauss.