starship-design: Re: Aliens, Why don't we see them?

[TLG.van.der.Linden@tip.nl (Timothy van der Linden)]

Lee,

>Zeno's Paradox dealt with why the sky was dark at night. His reasoning 
>(logic) was simply that there were an infinite number of stars so there
>should be an infinite amount of starlight falling upon the Earth all the 
>time, even at night, therefore it would never get dark, but since it was
>obviously not light at night there was a paradox. Of course the error in 
>his reasoning was two-fold. First of all, there aren't an infinite 
>number of stars; and second, the concept of infinities were not yet 
>properly understood. I paraphrased this (from memory) heavily, so please 
>excuse any errors or omissions.

Even if the universe was infinitely large, then the sky would still not need
to be bright everywhere. In math it is perfectly possible to sum an infinite
amount of numbers without getting an infinite answer. Indeed Zeno didn't
know this.

>The point I was making is that even though there aren't an infinite 
>number of stars (and therefore a finite number of possible civilizations)
>the number is still large enough that assuming ANY figure for a percent
>of stars with star-faring civilizations, there would still be so many
>that we would HAVE to see some evidence somewhere. Yet we don't. I'm not
>concluding there is a paradox here :-), just that something is wrong
>with our fundamental assumptions about the frequency of life on other 
>worlds. In any event I find it difficult to accept that we are alone, 
>but observational evidence would seem to indicate that this is the case.

Certainly not any number for a percent of stars with starfaring
civilizations would produce a large enough chance to easely see them.
I can think of reasonable numbers (with explanation) that decrease the
number of detectable space-faring civilizations per galaxy to rather small
numbers.

>Well that certainly sounds logical but your fundamental assertion is not 
>valid, therefore the remaining arguments, however good, are also suspect.
>You cannot base an analysis of anything (much less social dynamics) on 
>a single sample. Which effectively speaking is what Earth's entire 
>ecosystem is - a single sample.

This has little to do with biology or single samples. It is just logic.
Space technology needs a lot of effort to realize. It has to be a logical
fact that no single organism can do that much work.

>As for the remainder of the arguments, they don't even hold for humans 
>(just ask any student of international politics).

It would be handy if you told me...
Note that we are talking about civilizations that have no need anymore, to
kill for resources (land, food, energy).

Timothy