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Path: utzoo!linus!philabs!pwa-b!mmintl!franka
From: franka@mmintl.UUCP (Frank Adams)
Newsgroups: net.sf-lovers
Subject: Re: What an advanced race would come far to get....
Message-ID: <544@mmintl.UUCP>
Date: Mon, 29-Jul-85 14:30:24 EDT
Article-I.D.: mmintl.544
Posted: Mon Jul 29 14:30:24 1985
Date-Received: Wed, 31-Jul-85 22:36:48 EDT
References: <525@mmintl.UUCP> <988@umcp-cs.UUCP>
Reply-To: franka@mmintl.UUCP (Frank Adams)
Organization: Multimate International, E. Hartford, CT
Lines: 72
Summary: 


In article <988@umcp-cs.UUCP> mangoe@umcp-cs.UUCP (Charley Wingate) writes:
>In article <525@mmintl.UUCP> franka@mmintl.UUCP (Frank Adams) writes:
>
>>Besides, there is an underlying fallacy here: the idea that there is such
>>a thing as enough living space.  Exponential growth will use up whatever
>>space is available, in relatively short order.
>
>This itself is a fallacy, on two counts.  As far as humans are concerned,
>exponential is characteristic of a certain phase of technological and cultural
>development.  Most developed societies today have either slowly growing or
>stable populations.  I terms of other races, well, whose to say?  I would
>venture to guess, however, that a race which had an unalterable tendency
>towards high growth rates would have a hard time developing adequate
>technology; too much effort would be going into people starving.

I believe that stable populations are a temporary anomaly.  Only populations
which lack room to expand are stable.  The reason is that that which holds
still is sooner or later overwhelmed by that which keeps growing.  This is
a fundamental fact for both biological and cultural evolution.

You are confusing "exponential" growth rates with "high" growth rates.
Exponential means that the annual growth is some fraction of the total
population.  For growth to not be exponential, ultimately all but a tiny
fraction of the populated area must have ZPG.

My example assumes a growth rate of .7 to 3%.  We have acheived considerable
technological gains with a growth rate in that range.  But even a growth rate
two or three orders of magnitude lower doesn't change the argument
significantly: you run out of space very quickly, as measured by an
astronomical time scale.  And remember, it only takes ONE race to fill
the entire galaxy.

>>  This will get
>>us to the nearest star in about forty years.
>
>That's a generation ship.  Very few women are fertile after 40 years.

Perhaps a one-generation ship :-).  It's not "our great great grandchildren
will get there."

>> That gets us there in about seven years (a bit less
>>for the travelers.)  Right now it looks like the biggest problem with this
>>drive is producing anti-matter economically (it can already be produced,
>>using particle accelerators, it's just fantastically expensive).
>
>Well, unless you are going to break out of the current laws of physics, it
>takes the same amount of energy to get there in a certain time no matter how
>you store the power.  You either have to generate it along the way, or produce
>it all at the beginning and store it somewhere (and storage isn't necessarily
>a problem).

Storage probably is the problem, unless you generate it along the way.
Even assuming fusion, the reaction mass is significant compared to the
size of the ship.  That means you have to carry more reaction mass to
accelerate the fuel, and you wind up using LOTS of energy.  Of course,
a ramjet will solve the problem, but ramjets may or may not be workable.
My point is that there a lot of potential technologies, and almost
certainly, SOME of them work.

>  And it's a LOT of energy, all of which you have to get rid of
>if you expect to stop when you get there.

The seven year figure assumes you accelerate halfway, and decelarate the
other half.

>Charley Wingate  umcp-cs!mangoe
>
>"Tom, how am I going to generate that kind of power?  It can't be done!"

There is plenty of energy available from the sun.  If you wanted to move
whole planets, it would get problematical, but for spacecraft there is
no problem.