Over recent weeks, this author has been re-watching various
episodes from the original Star Trek series that first came out
in the mid-1960s. One of the classic episodes from that series
is entitled "The Devil in the Dark," and in that episode, the
Enterprise crew encounters a lifeform known as the "Horta." The
Horta would seem to fit the expression of "life Ð not as we know
it," for it turns out to be based on the element silicon.
Silicon-based life is sometimes encountered in various science
fiction tales, as it does seem to provide an interesting example
of "life not as we know it." But is it likely that there could
ever exist silicon-based life? Is it even possible? To examine
this issue, one must first examine "life as we know it," i.e.,
the life that exists here on Earth.  All life on Earth is based
upon the element carbon. In addition to being one of the most
abundant elements in the universe, the carbon atom has bonding
properties that allow it to form strong chemical bonds with
other carbon atoms an