Xenobiology





Xenobiology (or exobiology, or astrobiology) is the term for a speculative
field within biology which considers the possibility of, and possible nature
of, extraterrestrial life. It also necessarily includes the concept of
artificial life, since any life form might naturally evolve elsewhere, could
conceivably come out of a laboratory using a future technology. It might be
difficult to tell whether a truly strange life form had in fact arisen in
space, or was designed much nearer to home.

Although this is currently a speculative field, the absence of life in the
rest of the Universe is a falsifiable hypothesis (though it is yet to be
proven false), making Xenobiology a valid field for scientific enquiry.
Likewise, computer simulations of basic life processes have made it possible
to do exploratory engineering of alternate life forms (like left-handed DNA)
to determine their characteristics.

For these reasons the search for extraterrestrial life is of great relevance
to xenobiologists. Some contend that the number of planets with intelligent
extraterrestrial life can be estimated from the Drake equation if and when
we ascertain the values of its variables. However uncertainties in the term
of the equation make it impossible to predict whether life is rare or
common. Another associated topic in xenobiology is the Fermi paradox, which
suggests that if intelligent life is common in the universe then there
should be obvious signs of it.

There is no current evidence for intelligent extraterrestrial life (as of
2003). However examination of meteors from Antarctica which are presumed to
have originated from the planet Mars have provided what some scientists
believe to be microfossils of extraterrestrial life, although that
interpretation of the evidence is still controversial.

----------------------------------------------------------------------------

Xenobiology also features in much science fiction as the fictional science
of the biology of alien organisms. This use of the term demonstrates the
speculative generation of possible models of such life, e.g. based on silicon.