Extraterrestrial life and life potential of terrestrial organisms of great geological age: an historical and philosophical view

摘要

From the first noteworthy investigations of possible extraterrestrial organisms, many subsequent studies have generated heated controversies about extraterrestrial life even until today. Many scientists and visionaries presaged our remarkable, growing paradigm shift resulting from the indomitable idea that the proven scientific fact of extraterrestrial life is an inevitability. It is likely that most `revived' ancient microorganisms would not be very similar to any related modern microorganisms, because of the great time span available for the latter to diversity from the former. On the other hand, it is known that some complex brachiopod species of the common genus, Lingula, have survived for over a half billion years with `little evident change' since Cambrian times. Indirect evidence against modern contamination is offered by the fact that most `revived' bacteria from older terrestrial rocks are unlike any known modern species, and many microfossil-like structures (alleged by skeptics to be contaminants) in carbonaceous meteorites are yet to be confirmed as terrestrial in origin.