Alternative biochemistry - Silicon biochemistry

Alternative biochemistry collectively refers to an assortment of astrobiology theories and hypotheses in which life is based on chemical systems other than those used by currently known forms of life. Proponents of such theories sometimes use the expression carbon chauvinism to disparage the assumption that carbon molecules are necessarily the basis for all life. Up to this point, however, no non-carbon based life-form has been discovered. Alternative biochemistry - Silicon biochemistry. The most com ...

Including:

• Alternative biochemistry - Silicon biochemistry
• Alternative biochemistry - Nitrogen/Phosphorus biochemistry
• Alternative biochemistry - Other exotic biochemical elements
• Alternative biochemistry - Non-water solvents
• Alternative biochemistry - Ammonia
• Alternative biochemistry - Other solvents
• Alternative biochemistry - Artificial life
• Alternative biochemistry - In fiction

Read more here: » Alternative biochemistry: Encyclopedia - Alternative biochemistry

The most common other proposed basis is silicon, since silicon has many similar chemical properties to carbon. Silicon has a number of handicaps as a carbon analogue, however. Because silicon atoms are much bigger, they have difficulty forming double or triple bonds. Silanes (hydrogen-silicon compounds analogous to the alkane hydrocarbons) are highly reactive with water, and long-chain silanes spontaneously decompose. Molecules incorporating Si-O-Si bonds (known collectively as silicones) instead of Si-Si bonds are much more stable; ordinary ...

See also:

Alternative biochemistry, Alternative biochemistry - Silicon biochemistry, Alternative biochemistry - Nitrogen/Phosphorus biochemistry, Alternative biochemistry - Other exotic biochemical elements, Alternative biochemistry - Non-water solvents, Alternative biochemistry - Ammonia, Alternative biochemistry - Other solvents, Alternative biochemistry - Artificial life, Alternative biochemistry - In fiction

Read more here: » Alternative biochemistry: Encyclopedia II - Alternative biochemistry - Silicon biochemistry

In the realm of science fiction there have occasionally been forms of life proposed that, while often highly speculative and unsupported by rigorous theoretical examination, are nevertheless interesting and in some cases even somewhat plausible. One of the major sentient species in Terry Pratchett's Discworld universe is Trolls. Their being mineral-based has various interesting effects on their physiology and culture. Trolls eat rocks, which suggests that their biochemistry is similar to that of plants. A heterotrophic silicon-based l ...

See also:

Alternative biochemistry, Alternative biochemistry - Silicon biochemistry, Alternative biochemistry - Nitrogen/Phosphorus biochemistry, Alternative biochemistry - Other exotic biochemical elements, Alternative biochemistry - Non-water solvents, Alternative biochemistry - Ammonia, Alternative biochemistry - Other solvents, Alternative biochemistry - Artificial life, Alternative biochemistry - In fiction

Read more here: » Alternative biochemistry: Encyclopedia II - Alternative biochemistry - In fiction

See main article Artificial Life It is possible in principle to construct a robot or a system of robots that is capable of replicating itself from raw ores and natural energy sources without any external direction or assistance (a "clanking replicator"). Such a machine system could be considered alive, in that it is capable of evolution through mutational errors in its inherited design patterns, but is in no way required to be composed of carbon-based compounds. The most detailed proposition for machine life made so far conside ...

See also:

Alternative biochemistry, Alternative biochemistry - Silicon biochemistry, Alternative biochemistry - Nitrogen/Phosphorus biochemistry, Alternative biochemistry - Other exotic biochemical elements, Alternative biochemistry - Non-water solvents, Alternative biochemistry - Ammonia, Alternative biochemistry - Other solvents, Alternative biochemistry - Artificial life, Alternative biochemistry - In fiction

Read more here: » Alternative biochemistry: Encyclopedia II - Alternative biochemistry - Artificial life

In addition to carbon compounds all currently known terrestrial life also requires water as a solvent. It is sometimes assumed that water is the only suitable chemical to fill this role. Some of the properties of water that are important for life processes include a large temperature range over which it is liquid, a high heat capacity useful for temperature regulation, a large heat of vaporization, and the ability to dissolve a wide variety of compounds. There are other chemicals with similar properties that have sometimes been proposed as alternatives.See also:

Alternative biochemistry, Alternative biochemistry - Silicon biochemistry, Alternative biochemistry - Nitrogen/Phosphorus biochemistry, Alternative biochemistry - Other exotic biochemical elements, Alternative biochemistry - Non-water solvents, Alternative biochemistry - Ammonia, Alternative biochemistry - Other solvents, Alternative biochemistry - Artificial life, Alternative biochemistry - In fiction

Read more here: » Alternative biochemistry: Encyclopedia II - Alternative biochemistry - Non-water solvents

Nitrogen and phosphorus also offer possibilities as the basis for biochemical molecules. Phosphorus can form long chain molecules on its own like carbon, and so potentially could be built up into complex macromolecules, but phosphorus is fairly reactive. In combination with nitrogen, however, it can form much more stable phosphorus-nitrogen (P-N) bonds; compounds containing these can form a wide range of molecules, including rings. Earth's atmosphere is approximately 80% nitrogen, but this would probably not be much use to a P-N lifef ...

See also:

Alternative biochemistry, Alternative biochemistry - Silicon biochemistry, Alternative biochemistry - Nitrogen/Phosphorus biochemistry, Alternative biochemistry - Other exotic biochemical elements, Alternative biochemistry - Non-water solvents, Alternative biochemistry - Ammonia, Alternative biochemistry - Other solvents, Alternative biochemistry - Artificial life, Alternative biochemistry - In fiction

Read more here: » Alternative biochemistry: Encyclopedia II - Alternative biochemistry - Nitrogen/Phosphorus biochemistry

Chlorine is sometimes proposed as a biological alternative to oxygen, either in carbon-based biologies or hypothetical non-carbon-based ones. Chlorine is much less abundant than oxygen in the universe, however, and so it is unlikely that a planet will be able to form which has a large enough concentration of chlorine available on its surface to form the basis of a biochemistry. Chlorine will instead likely be bound up in the form of salts and other inert compounds. Sulfur is also able to form long-chain molecules, but suffers from the ...

See also:

Alternative biochemistry, Alternative biochemistry - Silicon biochemistry, Alternative biochemistry - Nitrogen/Phosphorus biochemistry, Alternative biochemistry - Other exotic biochemical elements, Alternative biochemistry - Non-water solvents, Alternative biochemistry - Ammonia, Alternative biochemistry - Other solvents, Alternative biochemistry - Artificial life, Alternative biochemistry - In fiction

Read more here: » Alternative biochemistry: Encyclopedia II - Alternative biochemistry - Other exotic biochemical elements