ASTRONOMERS may have unwittingly hastened the end of the Universe*

 From correspondents in Paris

November 22, 2007 09:03am
Article from: Agence France-Presse

ASTRONOMERS may have unwittingly hastened the end of the Universe by
simply looking at it, according to a theory reported in the latest
edition of 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, Mr Krauss believed.

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.

Mr Krauss and colleague James Dent pointed to measurements of light from
supernovae in 1998 that provided the first evidence of dark energy.

These measurements might 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, said Mr Dent
and Mr Krauss.

"Incredible as it seems, our detection of the dark energy may have
reduced the life expectancy of the universe,'' said Mr Krauss.

"We may have snatched away the possibility of long-term survival for our
universe and made it more likely it will decay.''