Universe is 'doomed to collapse'

It is all going to disappear one way or another ŠNasa

By Dr David Whitehouse BBC News Online science editor

Forget the idea that we live in a youthful universe.

If two American professors are correct, the cosmos is middle-aged.

And it has not got an old age to look forward to.

Despite what recent observations suggest, Professor Andrei Linde from Stanford University and his wife Professor Renata Kallosh say the universe will stop expanding and collapse in the relatively near future.

New insights into the mysterious "dark energy" that appears to be pushing the universe apart suggest it may eventually lose its power.

Turning away from the dark side, the cosmos will then collapse, as if everything was falling into a black hole, say researchers.

Islands of dying stars

It was in 1998 that two teams of astronomers discovered that not only was the universe expanding, it was doing so at an ever-faster rate.

Their astonishing findings were based on observations of supernovae - exploding stars that can be seen on the other side of the universe.

To explain this puzzle astronomers resurrected an idea originally from Einstein that there is in seemingly empty space a form of vacuum energy, sometimes referred to as dark energy, which is pushing everything apart.

The expansion of our universe at an ever-increasing rate implied a dark and lonely future for our galaxy.

All the galaxies would move far apart from one another, becoming isolated islands of dying stars with each galaxy no longer visible from any other.

The standard vision at the moment is that the universe is speeding up so we were surprised to find that a collapse could happen within such a short amount of time.

Professor Andrei Linde

Our own Milky Way would become an isolated island adrift in an unchanging sea of totally black space 150 billion years from now.

Over time all the stars in all the galaxies would fade, leaving an ever-cooling collection of stellar cinders and frozen planets that over billions of billions of years would become swallowed up by black holes.

But a new look at the fate of the universe adds a new twist to this so-called "heat death" scenario and suggests the fate of the cosmos is to become thin and lukewarm.

Doomed to disappear

The new approach does not deny that the universe is accelerating.

But it predicts that this acceleration will cease and be followed by a cosmic collapse in a "mere" 10 to 20 billion years.

Professor Linde said: "The standard vision at the moment is that the universe is speeding up so we were surprised to find that a collapse could happen within such a short amount of time."

Prof Linde and Prof Kallosh are highly respected physicists ŠStanford Univ

The couple - both physics professors - have produced two companion studies which suggest a cosmic "big crunch" is possible despite the observation that the universe is expanding.

Professor Linde said: "The universe may be doomed to collapse and disappear."

According to Professor Linde and Professor Kallosh the properties of the dark energy could be changing in a way which will eventually neutralise its influence.

Professor Linde said: "We have found that some of the best attempts to describe dark energy predict that it will gradually become negative, which will cause the Universe to become unstable, then collapse."

'Middle of the life cycle'

To put that into perspective, the universe is estimated to be about 14 billion years old, so according to the Stanford pair it has now reached middle age.

Professor Linde said: "Physicists have known that dark energy could become negative and the universe could collapse some time in the very distant future, perhaps in a trillion years, but now we see that we might be not at the beginning, but in the middle of the life cycle of our universe."

The good news, say the professors, is that "we still have a lot of time to find out whether this is going to happen".