Shortening the universe

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Mankind 'shortening the universe's life'

By Roger Highfield, Science Editor

Last Updated: 12:01am GMT 21/11/2007

 

 

 

 

Forget about the threat that mankind poses to the Earth: our

activities may be shortening the life of the universe too.

 

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The startling claim is made by a pair of American cosmologists

investigating the consequences for the cosmos of quantum theory, the

most successful theory we have. Over the past few years, cosmologists

have taken this powerful theory of what happens at the level of

subatomic particles and tried to extend it to understand the

universe, since it began in the subatomic realm during the Big Bang.

 

 

Cosmologists claim by observing dark energy the universe has been

nudged closer to its death

 

 

But there is an odd feature of the theory that philosophers and

scientists still argue about. In a nutshell, the theory suggests that

we change things simply by looking at them and theorists have puzzled

over the implications for years.

 

They often illustrate their concerns about what the theory means with

mind-boggling experiments, notably Schrodinger's cat in which, thanks

to a fancy experimental set up, the moggy is both alive and dead

until someone decides to look, when it either carries on living, or

dies. That is, by one interpretation (by another, the universe splits

into two, one with a live cat and one with a dead one.)

 

New Scientist reports a worrying new variant as the cosmologists

claim that astronomers may have accidentally nudged the universe

closer to its death by observing dark energy, a mysterious anti

gravity force which is thought to be speeding up the expansion of the

cosmos.

 

The damaging allegations are made by Profs Lawrence Krauss of Case

Western Reserve University in Cleveland, Ohio, and James Dent of

Vanderbilt University, Nashville, who suggest that by making this

observation in 1998 we may have caused the cosmos to revert to an

earlier state when it was more likely to end. " Incredible as it

seems, our detection of the dark energy may have reduced the life-

expectancy of the universe, " Prof Krauss tells New Scientist.

 

The team came to this depressing conclusion by calculating how the

energy state of our universe - a kind of summation of all its

particles and all their energies - has evolved since the big bang of

creation 13.7 billion years ago.

 

Some mathematical theories suggest that, in the very beginning, there

was a void that possessed energy but was devoid of substance. Then

the void changed, converting energy into the hot matter of the big

bang. But the team suggests that the void did not convert as much

energy to matter as it could, retaining some, in the form of what we

now call dark energy, which now accelerates the expansion of the

cosmos.

 

Like the decay of a radioactive atom, such shifts in energy state

happen at random and it is possible that this could trigger a new big

bang. The good news is that theory suggests that the universe should

remain in its current state.

 

But the bad is that quantum theory says that whenever we observe or

measure something, we could stop it decaying due what is what is

called the " quantum Zeno effect, " which suggests that if

an " observer " makes repeated, quick observations of a microscopic

object undergoing change, the object can stop changing - just as a

watched kettle never boils.

 

In this case however, it turns out that quantum mechanics implies

that if an unstable system has survived for far longer than the

average such system should, then the probability that it will

continue to survive decreases more slowly than it otherwise would. By

resetting the clock, the survival probability would now once again

fall exponentially.

 

" The intriguing question is this, " Prof Krauss told the

Telegraph. " If we attempt to apply quantum mechanics to the universe

as a whole, and if our present state is unstable, then what sets the

clock that governs decay? Once we determine our current state by

observations, have we reset the clock? If so, as incredible as it may

seem, our detection of dark energy may have reduced the life

expectancy of our universe. "

 

Prof Krauss says that the measurement of the light from supernovae in

1998, which provided evidence of dark energy, may have reset the

decay of the void to zero - back to a point when the likelihood of

its surviving was falling rapidly. " In short, we may have snatched

away the possibility of long-term survival for our universe and made

it more likely it will decay, " says Prof Krauss. Not all agree, since

his interpretation hinges on one of the issues at the heart of

quantum theory - do you need people to do the observing?

 

This is not the only damage to the heavens that astronomers may have

caused. Our cosmos is now significantly lighter than scientists had

thought after an analysis of the amount of light given out by

galaxies concluded that some shone from lightweight electrons, not

heavyweight atoms. In all, the new analysis suggests that the

universe has lost about one fifth of its overall mass.

 

The discovery was made while trying to analyze clusters of galaxies -

the largest cosmological structures in the universe - and is not the

result of a cosmological diet but a major rethink of how to interpret

x-rays produced by the clusters.

 

Five years ago, a team at the University of Alabama in Huntsville

lead by Prof Richard Lieu reported finding large amounts of

extra " soft " (relatively low-energy) x-rays coming from the vast

space in the middle of galaxy clusters. Although the atoms that

emitted them were thought to be spread thinly through space (less

than one atom per cubit metre), they would have filled billions of

billions of cubic light years.

 

Their cumulative mass was thought to account for as much as ten

percent of the mass and gravity needed to hold together galaxies,

galaxy clusters and perhaps the universe itself.

 

But now the team has taken a closer look at data gathered by several

satellite instruments, including the Chandra X-ray Observatory and

have had a major rethink about these soft X-rays, the bottom line

being that this chunk of the universe should now be discounted.

 

The reason is that the soft x-rays thought to come from intergalactic

clouds of atomic gas probably emanated from lightweight electrons

instead.

 

If the source of so much x-ray energy is tiny electrons instead of

hefty atoms, it is says the team as if billions of lights thought to

come from billions of aircraft carriers were found instead to come

from billions of extremely bright fireflies.

 

" This means the mass of these x-ray emitting clouds is much less than

we initially thought it was, " said Dr. Max Bonamente. Instead, they

are produced by electrons travelling almost the speed of light (and

therefore " relativistic " ).

 

The discovery may also change what we think is the mix of elements in

the universe because these soft x rays mask the tell tale x ray

emissions of iron and other metals. " This is also telling us there is

fractionally more iron and other metals than we previously thought, "

said Bonamente. " Less mass but more metals. "

 

Results of this research by Bonamente, Jukka Nevalainen of Finland's

Helsinki Observatory and Prof Lieu have been published in the

Astrophysical Journal.

 

The calculated mass of the universe ranges anywhere from 10 to the

power of 53 kg to 10 to the power of 60 kg and is complicated by the

fact that there is invisible matter we cannot see, called dark matter.