427 Life in Space
These are the most sensible words about the position of humans in the universe I
have read yet. I reprint the whole
article from The Telegraph, London, via the SMH; here is the juicy bit …
“... our solar system is
barely middle aged and if we humans avoid self-destruction, the
"post-human" era beckons. Prolonged interstellar travel wouldn't be a
challenge to near-immortal "post-humans". Alternatively, small
spacecraft could carry genetic material, or "blueprints", via laser
transmission ("space travel" at the speed of light). And these could
trigger the assembly of living organisms in propitious (favourable) locations. Life seeded
from Earth could spread through the entire galaxy, evolving into a teeming
complexity far beyond what we can conceive. If so, our tiny planet - this pale
blue dot floating in space - could be the most important place in the entire
cosmos.”
This concept is not new to me at all. I have read about it many, many years ago in Frank Tipler's book The Physics of Immortality ... I have an essay about it MATRIX, in my book with not title but three definitions for the term en.light.en.ment
NASA's Kepler Space Telescope is
searching for rocky planets that can hold liquid water.
Photo: NASA
The starry sky is now far more
fascinating to us than it ever was to our forebears. Stars may seem just points
of light, but we've learnt recently that most are orbited by retinues of
planets, just as our sun is. Our galaxy probably harbours many billions of
planets. The most fascinating question of all is how many might harbour life –
even intelligent life? Could Kepler 438b be part of the answer?
Kepler 438b is a very Earth-like
planet whose discovery was announced this week. There's special interest in
"twins" of our Earth – planets the same size as ours, orbiting other
Sun-like stars. Kepler 438b is one of those. It's 475 light years away, and
it's on an orbit in the "Goldilocks zone" – not so close to its star
that water boils away, nor so far that it's perpetually icy. It was discovered
by the small telescope on board Nasa's Kepler spacecraft, which monitored the
brightness of 150,000 stars for more than three years. Some stars underwent
slight regular dimmings, caused by orbiting planets that transit in front of
them, blocking out a bit of their light.
The Kepler data has already revealed
many surprises. Our solar system may be far from typical. In some systems,
planets as big as Jupiter are circling so close to their star that their
"year" lasts only a few days. Some planets orbit binary stars – there
would be two "suns" in their sky. But we'd really like to see these
planets directly – not just their "silhouettes" as they pass in front
of their parent star. And that's hard. To realise just how hard, suppose an
alien astronomer with a powerful telescope was viewing the Earth from 30 light
years away – the distance of a nearby star. It would seem, in Carl Sagan's
phrase, a "pale blue dot", very close to a star (our sun) that far
outshines it: a firefly next to a searchlight.
But if the aliens could detect
Earth, they could learn quite a lot about it. The shade of blue would be
slightly different, depending on whether the Pacific Ocean or the Eurasian land
mass was facing them. They could infer the length of our day, the seasons, that
there are continents and oceans, and the climate. By analysing the faint light,
they could infer that the Earth had a biosphere.
We don't yet have telescopes
powerful enough to make such observations of planets beyond our solar system.
But before 2030, the unimaginatively named ELT ("Extremely Large
Telescope") planned by European astronomers will offer the combination of
light-gathering power and sharpness of imaging to draw such inferences about
those planets orbiting nearby, Sun-like stars. The ELT will have a mirror 39
metres across (actually a mosaic of 800 sheets of glass). A mountaintop in
Chile has been levelled to provide the optimum site; construction will soon
begin.
But should we expect life on these
distant worlds? It's the uncertain biology that's the main stumbling block. We
know how simple life evolved into our present biosphere. But we don't know how
the first life was generated from a "soup" of chemicals. It might
have involved a fluke so rare that it happened only once in the entire galaxy –
like shuffling a whole pack of cards into a perfect order. On the other hand,
this crucial transition might have been almost inevitable given the
"right" environment.
The stakes are so high that it's
surely worth searching for evidence of advanced alien life, though we may not
be able to recognise it. For some alien "brains" may package reality
in a fashion that we can't conceive of, and have a quite different perception
of reality. Others could be uncommunicative: living contemplative lives,
perhaps deep under some planetary ocean. The most durable form of
"life" may be machines whose creators had long ago been usurped or
become extinct. There may be a lot more out there than we could ever detect.
Absence of evidence wouldn't be evidence of absence.
Perhaps we'll one day "plug
in" to a galactic community. On the other hand, Earth's intricate
biosphere may be unique. But that would not render life a cosmic sideshow.
Interstellar travel in our lifetimes isn't realistic (the magic tricks used in
the movie Interstellar are, sadly, science fiction). But humans aren't the
culmination of evolution. Our solar system is barely middle aged and if we
humans avoid self-destruction, the "post-human" era beckons.
Prolonged interstellar travel wouldn't be a challenge to near-immortal
"post-humans". Alternatively, small spacecraft could carry genetic
material, or "blueprints", via laser transmission ("space
travel" at the speed of light). And these could trigger the assembly of
living organisms in propitious locations.
Life seeded from Earth could spread
through the entire galaxy, evolving into a teeming complexity far beyond what
we can conceive. If so, our tiny planet – this pale blue dot floating in space
– could be the most important place in the entire cosmos.
Lord Martin Rees is
the Astronomer Royal
The Telegraph,
London