Time is running out - literally, says scientist*

By Tom Chivers
Last Updated: 6:01am GMT 18/12/2007

It's the end of the world - but not as we know it.

A Spanish scientist suggests that the universe's end will come not with
a bang but standstill - that time is literally running out and will, one
day, stop altogether.

Professor Jose Senovilla, of the University of the Basque Country,
Bilbao, has put forward the theory as a rival to the idea of "dark
energy" - the strange antigravitational force that is posited to explain
a cosmic phenomenon that has baffled scientists.

It was noticed ten years ago that distant stars - the ones on the very
fringes of the universe - seemed to be moving faster than those nearer
to the centre, suggesting that they were accelerating as they shot
through space. Dark energy was suggested as a possible means of powering
that acceleration.

The problem is that no-one has any idea what it is or where it comes from.

Professor Senovilla's theory does away altogether with dark energy.
Instead, he says, the appearance of acceleration is caused by time
itself gradually slowing down, like a clock that needs winding.

While the change would be infinitesimally slow from an ordinary human
perspective, in the grander scales of cosmology - in which scientists
study ancient light from suns billions of years dead - it could be
easily measured.

Astronomers are able to decipher the expansion speed of the universe
using the so-called "red shift" technique.

Light from stars that are moving towards the earth is of higher
frequency than that from the same sort of stars moving away. The
principle is the same as that of an ambulance siren which gets higher as
it comes towards the listener but lower as it moves away. Similarly, a
star moving away appears redder in colour.

Scientists look for exploding stars, or supernovae, of certain types
that provide a benchmark to work against.

However, the accuracy of these measurements depend on time remaining
constant throughout the universe, says Prof Senovilla.

If time is indeed slowing down, then the far-distant, long-ago stars
seen by cosmologists would be from an era when time ran faster. It would
therefore, from our perspective, look as though they were accelerating.

"Our calculations show that we would think that the expansion of the
universe is accelerating," said Senovilla.

He takes the basis for his idea from the superstring theory, which
suggests that dimensions of time and space can move around and change
places. His suggestion is that our solitary time dimension is slowly
becoming a new space dimension.

In some number of billions of years, time would cease to be time
altogether - and everything will stop.

"Then everything will be frozen, like a snapshot of one instant,
forever," Prof Senovilla told New Scientist magazine.

"Our planet will be long gone by then."

While the theory is outlandish, it is not without support. Prof Gary
Gibbons, a cosmologist at Cambridge University, believes the idea has
merit. "We believe that time emerged during the Big Bang, and if time
can emerge, it can also disappear - that's just the reverse effect," he
said.