From: tkoenig@netcologne.de   
      
   One of the more ambitious aspects of SF tech are machines that   
   continue to work for a _very_ long time.   
      
   The thought that you can build a generation ship that lasts hundreds   
   of years, or that you can find alien machinery that still works   
   millions of years after their builders have left it, turns up   
   quite often.   
      
   How would this work for our current level of technology?   
      
   Glass should be OK over a very long timeframe.   
      
   Metals can last a long time in vacuum, or under a (really)   
   inert atmosphere, so that is feasible, unless water or   
   oxygen are present.   
      
   Lubricants for metal parts fare much worse - they would   
   evaporate, or turn to coke, or...   
      
   Electronics will degrade over time due to a multitude of   
   effects such as thermal diffusion of doping atoms, cosmic   
   rays, recrystallization etc.  The dielectric constants   
   of capacitors can break down, etc.   
      
   Polymers are much worse - they can depolymerize due to   
   radicals, yellow etc.  Their additives can migrate, or   
   they can break down.  This can have serious consequences   
   for elctronic or electric devices as well, if insulation   
   breaks down.   
      
   So - really long-lasting technology needs constant maintenance,   
   unless you want to postulate materials that are far different   
   from what we have today.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)