PANSPERMIA - UNLIKELY, UNSUPPORTED, BUT JUST POSSIBLE

The question - are we alone in the Universe? - has been discussed for at least 2500 years. Initially philosophical and religious beliefs were used as arguments, but for over 100 years the possible transfer of bacteria and other microorganisms from planets, comets or meteoroids to other planets - panspermia - has been seriously considered. Possible mechanisms for this transfer exist and some microorganisms are known to be extremely resistant to very low temperatures, very high vacuum and intense high-energy radiation. Hoyle and his colleagues have published many claims that interstellar grains are partly, or even wholly, bacteria and or diatoms and that life, evolution and many diseases would not have occurred on earth without panspermia. The evidence and interpretations presented have not been accepted by the general body of biologists or astronomers. The present situation is that panspermia is unlikely, so far completely unsupported, but is just possible.