There was a letter to Nature a few months ago that discussed the possiblity
of life spreading throughout the galaxy via the spread of spores. The idea
was that a sizeable impact with Earth, or like body, would put some spores
into space. I can't remember the details, but the idea was that if you
assume a small piece of soot with spores inside you could expect them to
survive millions of years. Once in space they would slowly spread outwards
from the sun under the pressure of solar radiation until they perhaps
reached another solar system and fell to a planet with suitable conditions;
where they could start the process of life all over, or perhaps out compete
whatever organisms had evolved separately.
best, patrick
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Patrick Wilken http://www.cs.monash.edu.au/~patrickw/
Editor: PSYCHE: An International Journal of Research on Consciousness
Secretary: The Association for the Scientific Study of Consciousness
http://psyche.cs.monash.edu.au/ http://www.phil.vt.edu/ASSC/