[asa] The cat strikes again!

Some things about physics are too crazy not to be true. This one tops them
all.

Burgy

  ROGER HIGHFIELD, Science Editor - Telegraph (U.K.)
 *A kind of cosmic variant of the Observer Effect. The odd thing, to me at
least, is that this report apparently assumes that humans are alone in the
universe. *
 Forget about the threat that mankind poses to the Earth: our activities may
be shortening the life of the universe too.

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.

The Boomerang Nebula, mankind 'shortening the universe's life'
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.
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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.

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Received on Tue Nov 27 17:06:30 2007