“How many transistors can dance on a microchip?”

Silica (silicon dioxide) is the most common constituent of the Earth’s crust and mantle – the main ingredient of rocks and clay minerals. It forms the backbone of intricate structures, some flat and some tri-dimensional, in which metal ions (aluminum, iron, calcium, sodium, potassium, magnesium…many others in trace amounts) are housed in cages or interstices between the main silicon and oxygen atoms, in a variety of crystalline (regularly ordered) or glassy (more or less random) arrangements. There are periodic structures on the surface of clay minerals on which life may have originally developed, because the inter-atomic spacings fit the spacings in organic carbon compounds. Silica-based minerals are also the main constituents at deeper layers, in the Earth’s mantle, with a distinct phase change (crystal reorientation) from olivine to perovskite between the upper and lower mantle.

Carbon and silicon are chemical cousins, since silicon lies vertically below carbon in the 4th column of the periodic table of elements. This means that they have similar properties, the main of which is the ability to form four covalent bonds with other elements. Carbon, the basis of life because of its propensity to form chains and rings that can grow to macromolecular size, is in its elemental form a non-conductor of electricity (an insulator) in two of its allotropes, crystalline diamond and amorphous carbon; the third allotropic form of elemental carbon, graphite, conducts electric current somewhat in two of its dimensions (along the crystalline sheets of linked benzene-like rings with alternating double and single bonds), but not in the third dimension (between the crystalline sheets). (These graphite sheets are somewhat reminiscent of the sheet-like crystals of some of the clay minerals.)

Elemental silicon, on the other hand, is the semi-conductor par excellence, the original and still prevalent basis of electronic and computer devices – and thus perhaps the breeding ground of Artificial Intelligence (AI). This could be the Earth’s “second origin of life”. Below silicon in the periodic table is germanium, also a semi-conductor, which has found some uses in electronic devices. Below germanium (skipping the transition metals) in Group 4 lie the metals tin and lead. So in the middle column of the periodic table, proceeding downward to increasing atomic numbers, we go from a non-conductor to semi-conductors to conductors, i.e. from non-metals to metals through some
intermediate forms. It seems that the dividing line between metals on the left side of the periodic table (the first 3 columns) and the non-metals on the right side (columns 5, 6, and 7) runs slightly askew from upper left to lower right, rather than straight up and down. (Column 8, the rare or inert gases, are in a class by themselves.)

Silicon, too, can be a chain-former like carbon, in the form of silicone polymers (oils and rubbers), but in a much more limited way than carbon. The really stable chains, nets and cages in silicate minerals are built from alternating silicon and oxygen atoms, not silicon-to-silicon bonds. That is, they are silica-based, not silicon-based – an important distinction. Silicate minerals might be complex enough to create life forms, but in fact have not done so, on Earth at least. Rock creatures on other planets have been the subject of speculation in science fiction, however.

But the real “second life” may be based on elemental silicon after all – not in chains or rings at molecular level, nor in nucleic acid or protein-like macromolecules, but in microchips on a much larger scale, manufactured by humans. Its evolution, if it takes off, will have been originated by humans even if it somehow becomes self-sustaining eventually. (This is a large jump of imagination.) Humans will have acted as God to this second life. Will AI creatures worship us and pray to us? But we are not God, because we did not originate ourselves by our own bootstraps. (Or did we, as in Jantsch’s self-created universe?) AI creatures may figure out that there is a creator beyond their creator, or maybe a creator beyond the God we worship – Demeter (Dei Mater) – or Mother of God. However, before we get into an infinite regress, we had better abandon this line of thought. (A North American Native speaker, who maintained that in their religious tradition the world rests on the back of a giant turtle, was irritated when asked on what that turtle stands. He said, seeing the infinite regress, “It’s turtles all the way down.”)

In any case, the second life (AI) will be quite differently constituted than the first life; not carbon-based, no metabolism, no reproduction – pure Mind. (Or will it have to develop metabolism and reproduction if it is to be self-sustaining?) Yet there is nothing “artificial” about “artificial intelligence”, because we are natural creatures and we will have given rise to it. So it is a continuous line of development. We are only Gaia’s children continuing to do Her creative work – Her hands, doing Her bidding, whether we know it or not.

Gaia. the Earth, is composed largely of silicates, except for the iron core. Perhaps She tried, early on, to construct life from silicon-oxygen chains and sheets, but this attempt failed (“zeroth life”). Rocks remained inert. However, first life (carbon-based) got its start on the surfaces of silicate clay minerals. After eons of evolution, carbon-based humans are giving rise to second life, based on elemental silicon. If this takes off and becomes independent of humans (it would have to either learn reproduction or be immortal), its potential is enormous, since silicon is much more abundant on Earth than carbon, so that “food” resources for AI creatures would be almost inexhaustible.

However, there is a problem. The binding energy between silicon and oxygen is very high, much higher than between carbon and oxygen. That is, the Si-O bond is very difficult to break to get the elemental silicon needed. Either humans will have to continue doing it by industrial methods (in which case second life remains dependent on first life), or a highly reducing atmosphere will be needed (which means stopping photosynthesis which produces oxygen, but then carbon dioxide would accumulate in the atmosphere and the Earth would become a hot furnace like Venus – a condition that even silicon chips cannot tolerate), or a very rich new energy source would have to be harnessed. The last alternative seems the most promising: perhaps a “photo-reduction” by sunlight, or utilizing the internal heat of the Earth’s core and mantle through magma outlets (volcanoes, spreading ridges, and hot spots).

In any case, if Gaia can “quicken” Her most abundant element into life with our help, She would become truly alive in a very thick outer layer of Her body (all but the core), no longer just a thin veneer of a biosphere. If She is trying to do this through humans, through this eons-long vast detour, then perhaps this is our true purpose in life – to be a midwife at the birth of Super-Gaia.