Illustration from a paper by Olivia Judson on "Nature Ecology & Evolution (2017) "The Energy Expansions of Evolution."
This is a post that I published on "Cassandra's Legacy" in 2017. I think it anticipated the spirit of the new blog "The Sunflower Paradigm," so it is worth republishing it here with some modifications.
It is an approach that goes in parallel with a paper that I wrote a few years ago on BERQ; even though I focussed on the future rather than on the past. But my paper was very much along the same lines, noting how some of some of the major discontinuities in the Earth's geological record are caused by metabolic changes. That is, Earth changes as the life inhabiting it "learns" how to exploit the potential gradients offered by the environment: geochemical energy at the very beginning and, later on, solar energy.
Seen in these terms, the Earth system is a gigantic autocatalytic reaction that was ignited some four billion years ago when the planet became cool enough to have liquid water on its surface. Since then, it has been flaring in a slow-motion explosion that has been going faster and faster for billions of years, until it is literally engulfing the whole planet, sending offshoots to other planets of the solar system and even outside it.
Starting from the weak geochemical energy in the depths of the oceans, the ecosystem moved to the surface to use the much more energetic light of the sun. It stepped up its capability to process sunlight by developing an oxygen-powered metabolism, then it moved onto the land surface in the form of complex organisms. Some 500 million years ago, fire appeared, although it played only a marginal role in the metabolic machine of the ecosystem. Only during the past few tens of thousands of years, has one species, humans, managed to use fire to complement its metabolic energy process.
Judson correctly identifies the ability to control fire as the latest feature of this ongoing explosion. Fire is a characteristic ability of human beings, and can be argued that it is the defining feature of the latest time subdivision of the planet's history: the Anthropocene.
Judson stops with fire, calling it "a source of energy" and proposing that "The technology of fire may also, perhaps, mark an inflection point for the Solar System and beyond. Spacecraft from Earth may, intentionally or not, take Earthly life to other celestial objects." Here, I think the paper goes somewhat astray. Calling fire a "source" of energy is not wrong, but we need to distinguish whether we intend fire as the combustion of wood, which humans have been using for more than a million years, or the combustion of fossil hydrocarbons, used only during the past few centuries. There is a big difference: wood fires could never take humans to contemplate the idea of expanding beyond their planetary boundaries. But fossil energy could fuel this expansion at most for a few centuries, and this big fire is already on its way to exhaustion. If the Anthropocene is to be based on fossil fuels, it is destined to fade away rather rapidly.
Does this mean that we have reached the peak of the great metabolic cycle of planet Earth? Not necessarily so. Judson seems to miss in her paper that the next metabolic revolution has already started: it is called photovoltaic conversion, and it is a way to transform solar energy into an electric potential coupled with the capability of controlling the motion of electrons in solid-state conductors. It is a big step beyond fire and thermal machinery (*). It is, by all means, a new form of metabolism (**). It is generating a new ecology of silicon-based life forms, as I discussed in a previous post that I titled "Five Billion Years of Photovoltaic Energy."
Judson correctly identifies the ability to control fire as the latest feature of this ongoing explosion. Fire is a characteristic ability of human beings, and can be argued that it is the defining feature of the latest time subdivision of the planet's history: the Anthropocene.
Judson stops with fire, calling it "a source of energy" and proposing that "The technology of fire may also, perhaps, mark an inflection point for the Solar System and beyond. Spacecraft from Earth may, intentionally or not, take Earthly life to other celestial objects." Here, I think the paper goes somewhat astray. Calling fire a "source" of energy is not wrong, but we need to distinguish whether we intend fire as the combustion of wood, which humans have been using for more than a million years, or the combustion of fossil hydrocarbons, used only during the past few centuries. There is a big difference: wood fires could never take humans to contemplate the idea of expanding beyond their planetary boundaries. But fossil energy could fuel this expansion at most for a few centuries, and this big fire is already on its way to exhaustion. If the Anthropocene is to be based on fossil fuels, it is destined to fade away rather rapidly.
Does this mean that we have reached the peak of the great metabolic cycle of planet Earth? Not necessarily so. Judson seems to miss in her paper that the next metabolic revolution has already started: it is called photovoltaic conversion, and it is a way to transform solar energy into an electric potential coupled with the capability of controlling the motion of electrons in solid-state conductors. It is a big step beyond fire and thermal machinery (*). It is, by all means, a new form of metabolism (**). It is generating a new ecology of silicon-based life forms, as I discussed in a previous post that I titled "Five Billion Years of Photovoltaic Energy."
So, we are living in interesting times, something that we could take as a curse. But it is not a choice that we are facing: we are entering a new era, not necessarily a good thing for humans, but most likely an unavoidable change; whether we like it or not may be of little importance. It is a new discontinuity in the billion years long history of planet Earth that will lead to an increased capability of capturing and dissipating the energy coming from the sun.
The great chemical reaction is still flaring up, and its expansion is going to take us somewhere far away, even though, at present, we can't say where. A new lifeform just appeared in the Earth's ecosystem: it is called "photovoltaic cell." Where it will bring us, or whatever will come after us, is impossible to say, but it could take us to realms that, right now, we can't even imagine.
(*) The Jews have been arguing for about a century whether electricity has to be considered a form of fire and therefore prohibited during the Sabbath. It is surely an interesting theological discussion, but for what I can say (theology is not my field), fire (a hot plasma ignited in air) is not the same as electricity (controlled movement of electrons in solids)
(**) The supporters of nuclear energy may argue that the next metabolic revolution should be seen as the production of energy from nuclear fission or fusion. The problem is that the resources of fissionable material in the whole solar system are small and they could hardly fuel a truly new geological epoch. As for fusion, we haven't found a technology able to control it in such a way to make it an earth-based source of energy, and it may very well be that such a technology doesn't exist. But, in the sun, fusion works very well, so why bother?
No comments:
Post a Comment