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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,