Lots of Winners in the Lottery
of Life
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Media
Release - School of Physics - UNSW and the Australian Centre
for Astrobiology
Wednesday May 15th 2001
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Without a direct
detection it seems impossible to say anything about how common life
is on other planets or even whether it exists.
However an analysis
of the short time it took simple life to appear on Earth suggests
that life may be common on other Earth-like planets.
In a paper entitled
"Does the Rapid Appearance of Life on Earth suggest that Life
is Common in the Universe?" two UNSW astronomers have applied
the simple idea that more probable events happen more rapidly than
less probable events.
Just as the
probability of winning a lottery can be inferred from how quickly
a lottery winner has won, they have inferred the probability of
life appearing on Earth-like planets from how quickly life appeared
on Earth.
Dr Charles Lineweaver,
one of the authors of the new analysis, explained: "The Earth
is about 4.5 billion years old. Life has been on Earth for about
4 billion years. High temperatures and large frequent sterilising
impacts probably prevented an earlier appearance of life. So life
seems to have appeared on Earth as soon as it could have. This rapid
appearance of life on Earth suggests that the emergence of life
may be common in the Universe. This suggestion is what we have quantified
in our paper," he said.
"Suppose
someone buys a lottery ticket every day for three days, losing on
the first two days and winning on the third. We can use this information
to infer something about the probability of winning the lottery.
For example, the probability is closer to one in three than one
in one thousand.
This is analogous
to our situation on Earth. We find ourselves in the group of planets
that have won the biogenetic lottery some time in the past. And
we also find that we won soon after life became possible on Earth."
Their analysis
indicates that more than a third of Earth-like planets in the Universe,
older than about 1 billion years, are likely to have simple life
and whatever else it has evolved into.
Dr Charles H.
Lineweaver is an ARC research astronomer and Senior Lecturer in
the School of Physics at the University of New South Wales and a
member of the Australian Centre for Astrobiology.
Tamara M. Davis
is a PhD student in the School of Physics, UNSW.
Their paper,
"Does the Rapid Appearance of Life on Earth Suggest that Life
is Common in the Universe?" will be published in the new journal
"Astrobiology" later this year and is available online
at
http://xxx.lanl.gov/abs/astro-ph/0205014
and
http://xxx.adelaide.edu.au/abs/astro-ph/0205014
Contact details:
Dr Lineweaver
Further information:
An article about
this research will appear in the 18 May issue of New Scientist.
(16 May in the UK). (Also online
version)
Dr Lineweaver
will speak about these findings at two conferences this winter:
The International Society for the Study of the Origin of Life meeting
in Oaxaca, Mexico in June, and at Bioastronomy 2002, an international
meeting organised by the newly formed Australian Centre for Astrobiology,
to be held at Hamilton Island, Australia from 7 to 12 July.
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Further Information
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Contact
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CONTACT DETAILS:
Dr Charles Lineweaver, tel. 9385 5168 (UNSW) or 9457 0372 (after
hours).
He will be delivering a paper on the role of neutrinos in cosmology
at a conference in New Zealand from 20 to 26 January but should
be contactable by
E-mail: charley@bat.phys.unsw.edu.au
Date issued: 18 January 2002
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