Alien life could be gas
Last Updated: 2:01pm BST 15/08/2007
Roger Highfield describes work that shows the quest for ET is too
obsessed with carbon and water
Extraterrestrials could consist of living, breeding, floating clouds of
interstellar dust, according to a study by an international team.
The traditional image of an extraterrestrial life form
As Dr McCoy often remarked in Star Trek, "it is life Jim, but not as we
know it": the team sets out a new way that matter can replicate and evolve -
two key properties of life - without depending on Earthly chemistry in the New
Journal of Physics, hinting at more exotic possibilities for extraterrestrial
life and a possible new explanation for the origin of life on Earth.
Life on Earth is composed of organic molecules, and can reproduce with
the help of carbon chemistry and liquid water. But last month the US National
Academy of Sciences warned that the "life as we know it" approach could easily
miss something exotic and called on scientists to keep an open mind.
Today's work sets out one unusual idea that particles of inorganic (non
carbon) dust may take on a life of their own, going beyond the silicon-based
life forms favoured by some science fiction stories.
Under the right conditions, particles of inorganic dust can become
organised into helical structures with lifelike properties, according to Prof
Vadim Tsytovich of the General Physics Institute, Russian Academy of Science,
in Moscow, who worked with colleagues there and at the Max-Planck Institute for
Extraterrestrial Physics in Garching, Germany and the University of Sydney,
Australia.
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The team studied the complex mixtures of inorganic materials in a plasma.
Plasma is essentially the fourth state of matter beyond solid, liquid and gas,
in which electrons are torn from atoms leaving behind a miasma of charged
particles, and is present in plasma displays, fluorescent lamps and neon signs.
Until now, physicists assumed that there could be little organisation in
such a cloud of particles. However, Prof Tsytovich and his colleagues
demonstrated that particles in a plasma can twist into corkscrew shapes, or
helical structures. These twisted strands are themselves electronically charged
and are attracted to each other.
Not only do these helical strands interact in a counterintuitive way in
which like can attract like, but they also undergo changes that are normally
associated with biological molecules, such as DNA and proteins, say the
researchers.
They can, for instance, divide to form two copies of the original
structure. These new structures can also interact to induce changes in their
neighbours and they can even evolve into yet more structures as less stable
ones break down, leaving behind only the fittest structures in the plasma.
"These complex, self-organised plasma structures exhibit all the
necessary properties to qualify them as candidates for inorganic living
matter," says Prof Tsytovich, "they are autonomous, they reproduce and they
evolve". The team says that future searches for extraterrestrials should take
this work into account.
Although the plasma conditions needed to form these helical structures
are common in outer space, the team says that plasmas can also form under more
down to earth conditions such as the point of a lightning strike.
The researchers hint that perhaps an inorganic form of life emerged on
the primordial Earth, which then acted as the template for the more familiar
organic molecules we know today.
The living plasma idea chimes with one put forward by Dr Graham
Cairns-Smith at the University of Glasgow, who has argued for decades a simple
intermediate step between dormant matter and organic life might be provided by
the self-replication of clay crystals in solution.
"Not being a plasma physicist I can not comment sensibly on the crucial
details, but I am of course sympathetic with the idea of looking for things
that can evolve but are not made of your standard 'molecules of life'", he
remarks.
"In connection with the origin of life what is needed first is not a
stockpile of particular molecules, but things that can evolve somehow - and for
long enough and far enough to do clever things, to look as if they had been
designed.
"The main interest in this new contribution is I think that new kinds of
replicators would increase the number of places in the universe where prolonged
evolutionary processes might take hold. And quite possibly a physics laboratory
might be one of these places."
http://www.telegraph.co.uk/earth/main.jhtml;jsessionid=HUY4WW2PMCUMZQFIQMFCFFOAVCBQYIV0?xml=/earth/2007/08/15/scialien115.xml
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