On  Thu, 5 Sep 96  hanson@dosh.hum.caltech.edu (Robin Hanson) Wrote:
                >Dyson's derivation [for life in an open universe] was                 
                >assuming you kept exactly the same hardware
                                 
That doesn't seem like a realistic assumption to me. In an open universe 
everything will keep getting colder and most things will get larger and  
weaker too. Life will have to keep adapting to new conditions.
                    
                 >No need  to spread out the hardware over trillions of light                 
                 >years 
                  
A heat engine will have to exploit very tiny differences in temperature and 
will be very inefficient as a result. To get a usable energy output it would  
need to be HUGE. 
All electromagnetic photons would be of VERY low energy and so would have to 
have an enormous wavelength. A simple quarter wavelength  antenna for a 
billion mile photon, or a billion light year one, would need to be 
astronomical, and then some. A reflector to concentrate the photons for 
energy use would be MUCH larger still.
               
                                           John K Clark       johnkc@well.com
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