FYI: Why Do We Only Search For Aliens That Resemble Life Here On Earth?

Dr. Seth Shostak makes a good point, H2O and carbon (when speaking of evolution) are convenient for forming life as well as being abundant in the universe.

I believe I read something about silicon based organisms being possible instead of the normal carbon based ones.

Liquid is only necessary because it is non-static and contains sufficient material.

On a gasseous planet, however, the very air would be dense enough to contain sufficient material and motile enough for chemical reaction. Life, in the form of microbiological dust, floating arround inside of a gaseous giant plantet seems equally plausable from the chemical reactivity perspective.

Lovelock, however, has already elliquently laid out the neccessity that life be a planetary phenomenon. Planets are, in general, closed loops (apart from solar radiation). As such, their stability is based on diversity. Diversity equals exspansion. Exspansion will planetize life in any evolutionary scenario.

Could universes be diverse? Could another universe have a totally different configuration from that of ours? Lets keep our minds open to ideas.

I have thought the same thing forever. Everyone's been brainwashed by science-fiction. The term "alien," in its own context is essentially "foreign," when something is of that nature, it may be hard to qauntify. It's not what is alien, it is what perceptions are lacking...

I wonder if life forms could be organized at a non-chemical level. Chemistry is about electrons. Perhaps life structures could exist and replicate without being dependent on electron transfer. If so, they sure wouldn't look much like us.

There is not a shred of evidence to support the idea that life of any other kind other than one essentially similar to that observed on this planet exists.

Indeed, close consideration of the properties of the chemical elements and their compounds precludes any other than minor departures from the structures we observe on this planet at a comparable stage of evolution

It is, of course, as easy to fantasize about "non-chemical" life forms. Fred Hoyle's "Black Cloud" was one of the early versions efforts. But there is no more rational reason to make such general assumptions than the invention of the many gods so common in our past.

Nevertheless, there is very good circumstantial evidence that the current biological phase will transition, by a process of self-assembly, into an inorganic phase. And that this is likely to occur within a few decades.

Furthermore, when we consider the observed genetic/technological evolutionary vector it is reasonable to assume that a form having appropriate adaptations for extraterrestrial life will subsequently develop.

Given the size of the observed universe, and being aware the "scattergun" way that nature seems to do its evolutionary business we could expect similar trains of events to be occurring elsewhere.

This is all discussed more fully in my recent book “Unusual Perspectives”, the full electronic edition of which can be freely downloaded from the eponymous website.