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Re: SETI public: Why is ET silent?
>David Ocame wrote:
>100,000 years ahead of us?
I think we should consider this a minimum. Earth took 4.5 billion years
to produce human beings. The homo genus emerged 1.5 million years ago.
Modern humans appeared about 50,000 years ago. Global technology such as
might produce evidence detectable to ETI appeared roughly 100-200 years
ago (radio, railways, industrialisation, growth of cities...). Even the
largest of these time frames - 1.5 million years - is a mere 1/3,000th of
the duration that life has existed on Earth - and that is to produce
something which was not dramatically more intelligent than a chimp. If we
want modern humans, that is 1/9,000,000th of the age of life on Earth.
To assert that there is any sense something 'inevitable' about
proto-sentient life appearing in the last 3,000th of the span of life on
a planet is pretty implausible. To suggest that intelligent life requires
precisely 8,999,999 iterations and then will appear is a whole lot *more*
implausible - in fact pretty crazy... This is compounded by the problem
of when life *started* on another planet (the galaxy is 10 billion years
or so old), and at what pace it evolved (presumably dependent on
available energy and chemistry, gravity, set-backs such as asteroids and
gamma bursts...) - and also by the potential distortions introduced by
the speed of light restriction (when we hear from them / meet them may
not be the same as when they reached the relevant technological level).
I suggest that it's profoundly unlikely that two species could hit the
same 100,000 year window of species development, in a highly variable
galaxy that is 10 billion years old.
But let's assume they could, that there are beings 'out there' who are
only 100,000 years ahead of us.
>David Ocame wrote:
>Let's consider our own behavior. If
>we could somehow bring back to life, a man frozen in the last ice age,
>would we not want to make contact? (I believe a fantasy movie has been made
>on this theme). Of the 'primitive' tribes deep in the remote areas of our
>planet, how many years ahead of them do we consider ourselves? And yet, we
>have contacted these tribes (the ones we know about).
I think the most legitimate answer would be 10,000 years, which is the
advent of agriculture. This allowed a completely new pattern of social
organisation - cities, for example - which created a far richer and
broader culture. Long-range trade exploded, innovation became favoured,
the state superseded the tribe. But if you are prepaed to accept that
agriculture is not the defining difference, then we come down to a meagre
few hundred. The first large-scale civilisation I am awqare of its the
Sumerians - around 5,000 years ago. So, for 'Contact' purposes, the most
remote human cultures are only 10,000 years adrift of us - or even as
little as 5,000. If we assume ETI is 100,000 years ahead of us, then the
human example you give is between 1/10 and 1/20th of the scale of the
challenge we might face.
But I think the challenge is far greater than that. Of the (say) 10,000
years difference between us and 'primitive' modern humans, only 200 have
been *technological* years. think where human technology might be in a
thousand years - nanotechnology, human consciousnesses in machines, true
artificial sentents, immortality, wild biological diversity of humans
engineerd to live in different environments (comets, Mars...). Would a
human who resided as code in a one-foot long 'city' of virtual beings in
orbit around Ganymede still crave contact with a stone age tribe? This
person might live their lives at 100 years per second, their entire
culture and technology could transform itself in a decade as much as we
have in the last 10,000 years. Their life would be enriched by direct
mind-to-mind traffic between billions of incoded individuals, and by
every form of data from every sensor the entirety of humanity has
And that's ONE thousand years from now! We are postulating that ETI might
have had technology for 100 times longer!
Would they have the remotest interest in us? Hard to tell. One thing is
pretty likely, though: contact would be a one-way affair. There would be
no question about who was in the driving seat.
>My point is, IMHO, that I don't think it is a matter of how far advanced ETI
>is. I think the problem lies in the statement "life as we know it".
...and one form we might not recognise is a form that is 100,000 years
ahead of us - let alone the several million years which is, IMO, more
likely. But you are right, David. You suggest there could be some forms
which might consider themselves alive but which we would not reecognise
as such - and that they might just as easily not recognise us. tSuch
forms could very easiuly exist - how would we know?
I think the truth is that all forms of SETI are looking for a very narrow
subset of what might be out there. They have to be sufficiaently like us
biologically for us to see them as alive / sentient. They have to have
technology similar enough to ours that we can recognise it as the product
of intelligence (radio/optical if we're talking electromagnetic SETI, or
machines if we're talking SETA, for probes, say). They have to be at a
level not too far from our own. They have to have a culture and set of
perceptions which are close enough to allow some meaningful degree of
dialogue. (If you just want to detect ETI, you can skip that last
criterion, but it was contact we were discussing.)
To my mind, what this means is that we can only hope achieve contact with
a small subset of whatever is there. If there are 100,000 sentient
species inthe galaxy today, we might find that only 10 of them were
detectable, and we could only communicate with 2 of those. So we're
playing the odds.
Of course, by the same token, each culture we do detect and communicate
with may know of another 2 or so, som,e of which may be different enough
from ours that we could not have detected them. so we may learn of
culture number 2 through contact with culture number 1. There could be
vast chains of links which connect wildly dissimilar cultures. the
galactic club cold have pretty broad membership, and still be invisible
to us until we detect ETI culture number 1.
Is this a possible answer to the question David Brin was posing? Why is
ETI silent? I wish I could get hold of a copy, I'd love to read it...
With season's best wishes to you all,