X-Message-Number: 30798
From: "Chris Manning" <>
References: <>
Subject: Re: the Fermi paradox
Date: Tue, 3 Jun 2008 00:20:20 +1000

----- Original Message ----- 
From: "CryoNet" <>
To: <>
Sent: Monday, June 02, 2008 7:00 PM
Subject: CryoNet #30794 - #30797


> Message #30795
> From: David Stodolsky <>
> Subject: Re: the Fermi paradox
> Date: Sun, 1 Jun 2008 12:09:49 +0200
> References: <>
>
> On 29 May 2008, at 14:50, Chris Manning wrote:
>
>> I don't know how many other people have thought of this, but one
>> reason why
>> we haven't detected other intelligent civilisations is that they are
>> likely
>> to be spread out in time as well as in space. Maybe a civilisation
>> like ours
>> existed on a planet of the star e Eridani (20 light years away) 5
>> million
>> years ago. They destroyed themselves in a devastating war.
>
> This is part of the Drake Equation. The problem is that it is
> extremely unlikely that every one of the civilizations that have
> existed in the previous 10 billion years in the Galaxy have destroyed
> themselves. If even one made it into space, then that civilization
> should have spread through the Galaxy long ago.

This is assuming that the number of such civilisations has been sufficiently 
great, and/or for the likelihood of the self-destruction of any given one to 
be sufficiently small.

Believe me, I have thought of that. I have probably thought of all of the 
fifty possible reasons that someone alluded to. I have thought about this a 
lot. I can't begin to understand people who say they aren't interested in 
whether intelligent beings exist other than on earth. There can be no 
greater question (except perhaps 'Is there a God?'). One of the reasons I 
have signed up for cryonics is that I would like to find out, if possible.

My email wasn't meant as literally as you appear to have construed it. I 
meant self-destruction as one of several plausible reasons why we haven't 
heard from them or detected either civilisations themselves or evidence of 
their present or past existence. Maybe they don't bother sending messages 
across interstellar distances, or they have discovered some other method of 
sending/receiving messages, or they use very tight beams.

Or they construct a Dyson sphere and start living on the inside, and lose 
interest in the outside Universe.

Or they discover and emigrate to some other 'Universe' which is more 
congenial in some way than our own.

I think a significant possibility which we would be arrogant not to accord a 
significant likelihood is that a sufficiently advanced civilisation would 
not be recognised by us. It is commonplace to read that our own civilisation 
has changed 'beyond recognition' in the space of decades, or will do so in 
the next few decades. Of course it is not meant literally. But what about a 
civilisation that managed to exist for millions of years? How can we even 
begin to imagine what they would be like?

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