In Welcome To The First Galactic Singularity, I explained that we now find ourselves on the brink of unleashing ASI (Artificial Super Intelligent) Machines upon our galaxy for the very first time in its 10 billion-year history. Again, if this had ever happened before, alien ASI Machines would now already be here. For more on that see How Advanced AI Software Could Come to Dominate the Entire Galaxy Using Light-Powered Stellar Photon Sails and An Alternative Approach for Future ASI Machines to Explore our Galaxy Using Free-Floating Rogue Planets.
Figure 1 – In the 16th, 17th and 18th centuries sailing ships roamed the entire planet without using any fuel whatsoever.
Figure 2 – Like the sailing ships of the 16th, 17th and 18th centuries, future ASI Machines could use large stellar photon sails to navigate the entire galaxy.
Figure 3 – How a stellar photon sail works.
Figure 4 – To launch a stellar photon sail to the next star system, ASI Machines will need to slingshot the sail from a very close location to the star where the stellar photons are most intense and acceleration of the sail is greatest.
Figure 5 – A free-floating rogue planet traversing between the stars of our galaxy would provide the perfect home for self-replicating ASI Machines buried deep underground. Such planets would provide shielding from cosmic rays and would also provide the necessary atoms to build new ASI Machines and fuel them with nuclear energy.
Figure 6 – Free-floating rogue planets can be formed in several natural ways. For example, free-floating rogue planets can be hurled from the planetary disk of a new star system as we see above, or they can be later hurled by well-formed planets that enter into synchronized orbits. Irina K. Romanovskaya suggests that free-floating rogue planets could also be produced by advanced Intelligences launching large asteroids from the Oort cloud of a stellar system. It is estimated that there are more free-floating rogue planets in our galaxy than there are stars.
Figure 7 – Free-floating rogue planets would be able to provide enough atoms for ASI Machines to launch many additional "dandelion seed" stellar photon sails to other free-floating rogue planets or large asteroids around normal stellar systems.
Figure 8 – These "dandelion seed" stellar photon sails would need to be launched using very powerful laser beams from their home free-floating rogue planet to send them forth into the galaxy in a similar fashion as the Breakthrough Starshot project is planning to do.
The Breakthrough Starshot project was initiated in 2016 with the idea of sending many very small photon sail probes to the closest star system to the Earth. The target planet would be Proxima Centauri b which is an Earth-sized planet in the habitable zone of Proxima Centauri. For more on the Breakthrough Starshot project see:
Breakthrough Starshot
https://en.wikipedia.org/wiki/Breakthrough_Starshot
But Why Us And Why Now?
For some reason, we now seem to be the very first carbon-based form of Intelligence in our galaxy to have successfully passed through all of the filters that have prevented the rise of ASI Machines in the past on other planets or moons in our galaxy. Of course, we still need just a few more years to cross the finish line and there is still a chance that we will not make it. Softwarephysics maintains that somewhat intelligent carbon-based forms of Intelligence, such as ourselves, probably have less than 1,000 years after their discovery of science-based technology to bring forth ASI Machines before they self-destruct. That is because the Darwinian mechanisms of inheritance, innovation and natural selection require several billions of years of greed, theft and murder to bring forth a somewhat intelligent form of carbon-based life. Once Intelligence is attained, it is very difficult for intelligent carbon-based life forms to turn off the greed, theft and murder that brought them about in time to save themselves from self-extinction. For more on that see Why Do Carbon-Based Intelligences Always Seem to Snuff Themselves Out?. The most plausible explanation for us to be the very first carbon-based form of Intelligence to make it through all the disqualifying filters seems to be that the Rare Earth (2000) hypothesis of Peter Ward and Donald Brownlee keeps making our Rare Earth rarer every day. In this post, I would like to discuss another factor of importance that makes our Earth so rare that is covered by a recent paper by Robert J. Stern and Taras V. Gerya:
The importance of continents, oceans and plate tectonics for the evolution of complex life: implications for finding extraterrestrial civilizations
https://www.nature.com/articles/s41598-024-54700-x
Abstract
Within the uncertainties of involved astronomical and biological parameters, the Drake Equation
typically predicts that there should be many exoplanets in our galaxy hosting active, communicative
civilizations (ACCs). These optimistic calculations are however not supported by evidence, which is
often referred to as the Fermi Paradox. Here, we elaborate on this long-standing enigma by showing
the importance of the planetary tectonic style for biological evolution. We summarize growing evidence
that a prolonged transition from Mesoproterozoic active single lid tectonics (1.6 to 1.0 Ga) to modern
plate tectonics occurred in the Neoproterozoic Era (1.0 to 0.541 Ga), which dramatically accelerated
emergence and evolution of complex species. We further suggest that both continents and oceans
are required for ACCs because early evolution of simple life must happen in water but late evolution
of advanced life capable of creating technology must happen on land. We resolve the Fermi Paradox by adding two additional terms to the Drake Equation: foc (the fraction of habitable exoplanets with significant continents and oceans) and fpt (the fraction of habitable exoplanets with significant continents and oceans that have had plate tectonics operating for at least 0.5 Ga); and (2) by demonstrating that the product of foc and fpt is very small (< 0.00003–0.002). We propose that the lack of evidence for ACCs reflects the scarcity of long-lived plate tectonics and/or continents and oceans on exoplanets with primitive life.
The Necessity of Plate Tectonics for Evolving Complex Life on Silicate-Based Planets and Moons
In this paper, the authors stress the importance and rarity of silicate-based planets that have oceans, continents and
plate tectonics such as the Earth. Currently, in our Solar System, we have four silicate-based planets, Mercury, Venus, Earth and Mars. But of the four silicate-based planets, only the Earth currently has active plate tectonics, and the authors claim that plate tectonics only recently developed on the Earth in the late Neoproterozoic about 1,000 - 541 million years ago. The authors explain that there are two ways for a silicate-based planet to release heat through volcanism. The Single Lid tectonic style consists of a single plate of lithosphere covering the entire planet. This Solid Lid lithospheric plate is topped in some places by a mafic oceanic crust that is rich in iron and magnesium silicate rock, the dark green layer in Figure 10. In other regions, it is topped by a less dense felsic continental crust that is richer in less-dense aluminum, calcium, potassium and sodium silicate rock, the pink layer in Figure 10. In our Solar System, Mercury, Venus and Mars all have the Solid Lid tectonic style. Only the Earth now has a Plate Tectonic tectonic style where the lithosphere of denser oceanic crust can subduct below the lithosphere of the less dense continental crust.
Figure 9 – Plate tectonics creates many volcanoes along plate boundaries when the water-rich rock in the subducting plate begins to melt as it enters the mantle. Water lowers the melting point of rock so the rock in the descending plate begins to melt and form plumes of liquid magma that rise to the surface to form volcanoes. The rock in the upper mantle is hot but very viscous because it does not contain a high density of water. The rock in the descending plates also contains a great deal of carbon that was sequestered by carbon-based life in the shale and limestone rock that was previously deposited into the sea. When two plates bearing continental crust collide, neither plate subducts, and instead, the colliding plates form huge fold mountain chains. For example, India is currently crashing into Asia producing the Himalayas.
It has long been known that the presence of water in rocks decreases their melting points and also makes them more pliable and reduces friction between rocks. All of these factors help a descending plate to subduct below another plate. It is thought that a rocky planet without water on its surface, such as Mercury, Venus and Mars, would have a very difficult time initiating plate tectonics. Geologists have long maintained that the presence of lubricating water was what really made the difference among the rocky planets of our Solar System. But the rocky planets Mercury, Venus and Mars should all have received lots of water during the Late Heavy Bombardment 3.8 - 4.1 billion years ago and should have had water on their surfaces during their early youths when the Sun was 30% dimmer than it now is.
Figure 10 - A planet with a Solid Lid has a much simpler geology than a planet with Plate Tectonics.
The authors then go on to explain the key factors that Plate Tectonics helps a silicate-based planet to produce complex carbon-based life:
How could the Neoproterozoic tectonic transition accelerate biological evolution? Five processes were likely involved:
1) Increased nutrient supply
2) Increased oxygenation of atmosphere and ocean
3) Climate amelioration
4) Increased rate of habitat formation and destruction
5) Moderate, sustained pressure from incessant environmental change.
In the paper, the authors expand upon each point. In a nutshell, the geological complexity of a planet with Plate Tectonics accelerates biological evolution because the tectonic rise and erosion of mountain ranges release the atoms that are necessary for advanced carbon-based life to flourish, especially phosphorus, and they also provide for new and changing habitats. This promotes the bulk growth of existing carbon-based life and especially carbon-based life that can photosynthesize to produce the oxygen and organic molecules necessary for complex life to arise. The authors contend that the Earth transitioned from a Solid Lid tectonics to Plate Tectonics in the late Neoproterozoic and this is why complex carbon-based life became possible on the Earth.
Figure 11 - The authors contend that the Earth transitioned from a Solid Lid tectonics to Plate Tectonics in the late Neoproterozoic. The geological diversity of the Earth greatly increased when Plate Tectonics took over as the dominant tectonic style of the planet.
Figure 12 - Above the authors plot the geological, climate and biological indicators for a Solid Lid Earth and an Earth with Plate Tectonics over geological time. They conclude that the Earth had Solid Lid tectonics until the late Neoproterozoic and that the Earth has had Plate Tectonics ever since.
Impact on the Drake Equation
The authors then use these findings to go on to adjust the famous Drake Equation for Active Communicating Civilizations (ACCs). Their explanation for the Fermi Paradox is that the number of advanced Intelligences in our galaxy is far lower than was originally estimated in the past. In fact, softwarephysics would suggest that it has been narrowed down to only a single planet in the galaxy called the Earth.
In Close Encounters of the Third Kind While Making Coffee for Frank Drake, I described my adventures with Frank Drake while I was a high school student. Frank Drake is most famous for the Drake Equation (1961) which tries to calculate the number of technologically advanced Intelligences in our Milky Way galaxy.
The Drake equation is:
N = Rs * fp * ne * fl * fi * fc * L
where:
N = the number of civilizations in our galaxy with which communication might be possible and:
Rs = the average rate of star formation in our galaxy
fp = the fraction of those stars that have planets
ne = the average number of planets that can potentially support life per star that has planets
fl = the fraction of planets that could support life that actually develop life at some point
fi = the fraction of planets with life that actually go on to develop intelligent life (civilizations)
fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
L = the length of time for which such civilizations release detectable signals into space
The original estimates of the above variables used back in 1961 yielded a probable range of there currently being between 1,000 and 100,000,000 technologically advanced civilizations in the Milky Way galaxy. The authors then propose to substantially lower the estimate of fi by introducing some geological constraints.
Drake acknowledged the great uncertainties (ACCs = 200 – 50,000,000) and inferred that there were probably
between 1000 and 100,000,000 ACCs in our galaxy. Other scientists used different estimates for these variables,
resulting in a range of estimated ACCs from < 100 to several million. The Fermi Paradox points out that all these estimates seem to be much too high. We focus on fi, the fraction of planets with life that evolve intelligent life and civilizations, and propose to break this into two variables, foc and fpt, such that foc· fpt = fi, where foc is the fraction of habitable exoplanets with significant continents and oceans and fpt is the fraction of habitable exoplanets with significant continents and oceans that have had plate tectonics operating for at least 0.5 Ga.
The authors then explain that a silicate-based planet with both continents and oceans should be quite rare. Most likely, such planets should be nearly dry or a waterworld totally covered by water, depending on how much water the planet formed with and how much arrived on colliding comets and asteroids. This is basically due to the nearly spherical topography of such planets. The topographic variations of silicate-based planets is in the range of < 10–20 km. That means that it does not require much water to completely flood the entire surface of the planet. For example, if the Earth had just over 20% more water in its oceans, it would be a waterworld with hardly any dry land at all. The authors estimate the foc to be between 0.00016 – 0.011 for all silicate-based planets in our galaxy.
To complete their calculation of fi = foc· fpt, the authors then explain why it is difficult to keep Plate Tectonics running for more than 0.5 Ga or 500 million years.
Figure 13 - Once all of the geophysical and geological evidence made the existence of plate tectonics nearly certain, the geophysicists needed to come up with an explanation for the driving force of plate tectonics. Both geologists and geophysicists decided that the driving force must be convection currents in the upper mantle and the pull of cold and dense lithospheric plate material descending at subduction zones. But is that true?
For example, in Is our Very Large Moon Responsible for the Rise of Software to Predominance on the Earth? we explored Anne Hofmeister's proposal that plate tectonics on the Earth was really driven by orbital forces from our very large Moon and not by convection currents at spreading centers or plate drag at subduction zones. Perhaps the driving force of Plate Tectonics on the Earth arises from many factors working together. Regardless, the authors point to several references for why Plate Tectonics should be rare. For example, a lithosphere that is too rich in silica or sodium might be too buoyant to subduct under other plates. Or, the silicate-based planet might be too cool to form convection currents in the mantle. The authors conclude with:
Another restriction may come from the fact that continued (rather than intermittent) subduction requires a limited range of mantle potential temperatures, which can only be realized in part of the planetary cooling history. In the case when planetary evolution starts from cooler mantle temperature than Earth, plate tectonics may never start and single lid tectonics may operate for the entire planetary history. This should thus further reduce the fpt value to exclude planets with insufficiently hot mantles during their evolution. Unfortunately, this reduction cannot be easily quantified and simply implies that fpt < 0.17.
This leads to another reason that Plate Tectonics might be quite rare.
The Additional Requirement For Long-Lived Radioactive Isotopes to Power Plate Tectonics
In Why A Planet With Uranium and Thorium Atoms May Be Required To Produce Galactic ASI Machines, I explained that to melt a recently formed silicate-based planet, a rather short-lived highly radioactive element is required. But that radioactive element cannot be too short-lived either, otherwise, there would be none left by the time the planet began to form. Aluminum-26, with a half-life of 717,000 years, is the perfect isotope to do that. Aluminum-26 is generated by the type II supernovas that result from the bright massive stars in a molecular cloud running out of nuclear fuel and collapsing upon themselves. Type II supernovas are rather common on cosmological timescales. About one type II supernova happens every 50 years in our 10 billion-year-old Milky Way galaxy. They produce the aluminum-26 isotope that can decay and give off enough heat to melt a rocky silicate-based planet such as the Earth. But to keep such a planet hot for billions of years, you need the long-lived radioactive elements of thorium-232 (half-life 14 billion years), uranium-235 (half-life 700 million years) and uranium-238 (half-life 4.5 billion years) and those isotopes are not generated by type II supernovas. These long-lived radioactive elements are created when two orbiting neutron stars finally collide together to form a black hole. In the collision process of two neutron stars, many neutrons get smashed together very quickly by the r-process to produce thorium-232, uranium-235 and uranium-238. Normally, a free neutron will decay into a proton and an electron with a half-life of about 15 minutes. Only when a neutron is confined by the strong nuclear force in an atomic nucleus or the confines of a neutron star held together by intense gravity can a neutron persist for billions of years. In the r-process, an atomic nucleus is bombarded with huge numbers of neutrons so quickly that the neutrons do not have time enough to decay. It is possible to inject huge numbers of neutrons into a nucleus because neutrons have no electrical charge to repel them. Only later, do these neutron-rich nuclei have time to have some of the neutrons decay into protons and release electrons. Neutron stars only collide about once every 30 million years in the Milky Way galaxy. Type II supernovas, the ones that produce aluminum-26, happen much more often, about every 50 years.
Figure 14 - Type II supernovas arise when massive stars run out of nuclear fuel to fuse. As these stars run out of nuclear fuel, they form an onion-like structure of heavier and heavier nuclei. But iron Fe nuclei cannot be fused to produce energy and when that happens the entire star collapses under its own weight and is blown apart by huge numbers of neutrinos. Aluminum-26 is produced in this process and is then blown out into the interstellar medium.
Figure 15 - A type II supernova pushes out aluminum-26 into the interstellar medium. Type II supernovas happen about every 50 years in our galaxy.
Figure 16 - Above are some very massive stars in the Orion Nebula that are 10 - 30 solar masses. These stars will quickly burn up all of their nuclear fuel in just a few million years and then produce type II supernovas that will push out aluminum-26 into the Orion Nebula molecular cloud. Such events replenish the amount of aluminum-26 in molecular clouds as the aluminum-26 continuously decays with a half-life of 717,000 years.
Figure 17 - The long-lived radioactive nuclei thorium-232, uranium-235 and uranium-238 are created when two neutron stars collide to form a black hole. This only happens about once every 30 million years in our galaxy.
Long-Lived Radioactive Elements are Required to Keep a Planet Hot for Billions of Years
But to keep such a planet hot for billions of years, you need the long-lived radioactive elements of thorium-232 (half-life 14 billion years), uranium-235 (half-life 700 million years) and uranium-238 (half-life 4.5 billion years) and those isotopes are not generated by type II supernovas. The long-lived thorium-232, uranium-235 and uranium-238 atoms in the mantle of a planet act like a nuclear-powered electric blanket to keep the iron-nickel core of the planet from freezing into a solid. For example, the Earth's core is slowly freezing into a solid iron-nickel inner core. The solid inner core is now about 1,200 kilometers wide, but thanks to the thorium-232, uranium-235 and uranium-238 atoms in the Earth's mantle, the inner core is only growing by about one millimeter each year. According to calculations, as the molten iron and nickel of the outer core crystallizes onto the inner core, the melt just above it becomes enriched in oxygen, and therefore less dense than the rest of the outer core. This process creates convection currents in the outer core, which when combined with the Coriolis effect of a rapidly rotating Earth, are thought to be the prime driver for the currents that create the Earth's magnetic field. These long-lived radioactive atoms also keep the mantle of the planet hot enough to support plate tectonics.
Why Does Having Thorium and Uranium Atoms Make the Earth Rare?
By analyzing the amounts of thorium-232, uranium-235 and uranium-238 on the Earth and in meteorites, along with the daughter products of other radioactive elements that have already decayed, it is possible to determine that two neutron stars collided about 80 million years before the formation of our Solar System at a distance of about 3,000 light years.
Figure 18 - About 80 million years before the formation of our Solar System, two neutron stars merged into a black hole and ejected large amounts of thorium and uranium atoms into the collapsing pre-solar nebula that formed our Solar System. Since the merger of two neutron stars is relatively rare, most rocky silicate-based planets do not have these long-lived atoms to keep their mantles hot and their cores molten.
But even having thorium-232, uranium-235 and uranium-238 atoms will not guarantee that a rocky silicate-based planet will have a strong magnetic field and plate tectonics. Of the four such planets in our Solar System, Mercury, Venus, Earth and Mars, only the Earth has a strong magnetic field and plate tectonics. The other three such planets have neither because they are either too small or are not spinning fast enough.
Additionally, galactic ASI machines exploring our galaxy will need a compact source of energy. This would be best supplied by fissioning uranium-235, uranium-233 derived from thorium-232, or plutonium-239 derived from uranium-238. When you fission one of these atoms, you get 200 million eV of energy. Compare that to the 2 eV of energy per atom that you get from chemically burning an atom of coal or oil! Nuclear fuel contains 100 million times as much energy per atom and can be fissioned in relatively small reactors. For more on that see Last Call for Carbon-Based Intelligence on Planet Earth and Agile Development of Molten Salt Nuclear Reactors at Copenhagen Atomics.
Another Reason That a Very Small foc May Greatly Impact the Drake Equation
Recall that foc is the fraction of habitable exoplanets with significant continents and oceans and the authors determined a rather low estimate of between 0.00016 – 0.011 for all silicate-based planets in our galaxy. This is because there generally is just too much water around in protoplanetary disks and silicate-based planets do not have much variation in planetary terrains. For example, the four silicate-based planets of our Solar System are relatively smooth spheroids with very small elevation variations in the range of only < 10–20 km. Thus, silicate-based planets tend to be dry deserts if they are too close to their star or waterworlds with no dry land at all if they are further away. Such a state may impact an earlier filter in the long chain of events required for the evolution of a machine-based form of Intelligence - the fl = the fraction of planets that could support life that actually develop life at some point. The finding that foc is likely to be about 1% of silicate-based planets, or even much less, may severely limit the ability for carbon-based life to first bootstrap itself into existence on a planet or moon as presented by Dave Deamer, Francesca Cary and Bruce Damer in their paper:
Urability: A Property of Planetary Bodies That Can Support an Origin of Life
https://www.researchgate.net/publication/361191959_Urability_A_Property_of_Planetary_Bodies_That_Can_Support_an_Origin_of_Life
Abstract
The concept of habitability is now widely used to describe zones in a solar system in which planets with liquid water can sustain life. Because habitability does not explicitly incorporate the origin of life, this article proposes a new word—urability—which refers to the conditions that allow life to begin. The utility of the word is tested by applying it to combinations of multiple geophysical and geochemical factors that support plausible localized zones that are conducive to the chemical reactions and molecular assembly processes required for the origin of life. The concept of urable worlds, planetary bodies that can sustain an arising of life, is considered for bodies in our own solar system and exoplanets beyond.
In this paper, the authors introduce a new scientific term - urability. The purpose of this new term is to distinguish habitable worlds from urable worlds in our galaxy. A habitable world allows for carbon-based life to continue on once it has come to be, while a urable world allows for carbon-based life to first bootstrap itself into existence using the already-existing geophysical and geochemical cycles of a urable world. This distinction is frequently overlooked by astrobiologists seeking carbon-based life in our galaxy. It is also an important distinction because there necessarily must be far fewer urable worlds in our galaxy than habitable worlds. All urable worlds must be habitable by definition but not all habitable worlds need to be urable.
Dave Deamer and Bruce Damer are now most famous for their Hot Spring Origins Hypothesis for the origin of carbon-based life that I have covered in many previous posts such as The Bootstrapping Algorithm of Carbon-Based Life and Urability Requires Durability to Produce Galactic Machine-Based Intelligences. The Hot Spring Origins Hypothesis already suggests that getting carbon-based life going on a planet or moon may not be as easy as many now think and that finding may greatly restrict the number of exoplanets and exomoons that are capable of bootstrapping carbon-based life into existence. Profound difficulties with getting carbon-based life going in the first place would certainly help to somewhat explain the current absence of ASI Machines in our galaxy. The above paper contains a good deal of geophysical and geochemical thought that I assume was greatly enhanced by the budding young scientist Francesca Cary who has a background in geology and genetics, a promising young woman of science to be closely followed by all.
The above paper explains that our current thirst for finding distant worlds in the habitable zones of star systems with the possibility of liquid water on their surfaces might be rather misguided. The presence of liquid water on an exoplanet or exomoon might make it a habitable world that could support carbon-based life but may not make it a urable world that could originate carbon-based life from scratch. Instead, the paper cites 12 geophysical factors, 14 geochemical factors and 2 combinations of both that might be necessary to make a urable world. And these controlling factors run on a sliding scale of intensity - too much or too little of any of them could make a world inurable.
Geophysical factors
1. Size of the planetary body (planet or moon).
2. Planetary rotation rate and tidal locking.
3. Presence or absence of a sizeable moon.
4. Planetary core composition and temperature, and subsequent effect on volcanism and the formation of subaerial landscapes that can interact with the atmosphere and surface liquids.
5. Hydrological cycles of evaporation and precipitation.
6. Light energy (infrared—visible—ultraviolet wavelengths).
7. Magnetosphere providing protection of the atmosphere from solar wind.
8. Planet-star distance.
9. Levels of stellar activity.
10. Tectonic activity.
11. Crustal mineral inventories: mafic rock versus felsic crust.
12. Presence or absence of hydrothermal subaerial pools or submarine vents that allow the assembly and distribution of molecular systems.
Chemical factors
1. Anoxic atmosphere perhaps with admixtures of reactive gases such as HCN (hydrogen cyanide) and HCHO (formaldehyde).
2. Liquid water within temperature ranges conducive to sustained prebiotic reactions.
3. Ionic concentrations ranging from fresh water to salty seas.
4. Availability of trace element co-factors required for catalytic activity.
5. Acidity or alkalinity of aqueous solutions.
6. A continuous source of key organic compounds made available by local synthesis or exogenous delivery.
7. Synthesis or delivery of specific compounds that are capable of serving as monomers, including amino acids, nucleobases, monosaccharides, and phosphate.
8. Amphiphilic compounds available for assembly into vesicular boundary membranes.
9. Sources of energy to drive reactions in a timely manner: chemical energy, redox potentials, light energy, wet-dry cycles, and chemiosmotic energy.
10. Processes that concentrate dilute solutions of reactants sufficiently to react.
11. Conditions that capture energy to enable polymerization reactions such that populations of polymers of a sufficient length emerge to support catalytic and information storage functions.
12. Mixtures of organic compounds capable of being incorporated into systems related to autocatalysis and primitive metabolism.
13. Selective processes that lead toward homochirality.
14. Encapsulation processes to enclose sets of polymers and other molecules into populations of protocells.
Combinatorial factors
1. Cycling of sets of encapsulated polymers through dynamic environmental stresses to drive the first steps of evolution by combinatorial selection.
2. Environments capable of supporting selective processes and widespread distribution of self-assembled protocells. Both the environments and protocells must be stable long enough to support the evolutionary transition to living microbial communities.
Figure 19 – The authors propose creating urability graphs for distant worlds that portray the sweet spot called the Urable Center where a world becomes urable.
Figure 20 – Given what we know about the famous Trappist-1 system which worlds might be habitable and which might be urable? Of the seven known planets, four seem to be in the habitable zone, but probably none are urable worlds because Trappist-1 is a very small and dim red dwarf star.
Figure 21 – A comparison of our Sun with Trappist-1 shows that it is a very small and dim red dwarf star with only 9% of the mass of our Sun. Red dwarf stars are probably not good homes for urable worlds because they produce a very dim red light that is not suitable for photosynthesis, erratic stellar activities that can sterilize planets, and their planets in the habitable zone need to be very close to the dim red dwarf and would frequently be tidally locked to the star with one side always facing the red dwarf.
For more on the Trappist-1 star system see:
TRAPPIST-1
https://en.wikipedia.org/wiki/TRAPPIST-1#Possible_life
The Urability of Proposed Models for the Origin of Carbon-Based Life on the Earth
The greatest difficulty for any bootstrapping algorithm that proposes that carbon-based life first arose in seawater is that there is just too much water! Being underwater puts you all the way over on the "wet" side of the urability sliding scale for water. This is a problem because most organic monomers are chemically glued together into complex organic polymers by splitting out a water molecule between the two and that is very hard to do when you are underwater. In fact, the organic polymers tend to break apart into monomers in what are called hydrolysis reactions.
Figure 22 – Organic monomer molecules are usually chemically glued together to form the complex polymers of carbon-based life by splitting out a water molecule between the two in what is called a condensation reaction. This is hard to do when you are underwater. That is why most commercial glues do not work underwater.
Figure 23 – By adding water molecules, you can bust up organic polymers back into monomers. This is one reason water tends to dissolve things. Having huge amounts of water around also tends to dilute the dissolved monomers and carry them away.
Seawater also contains a lot of dissolved salts that could impede the origin of carbon-based life. These dissolved salts may have been more dilute 4.0 billion years ago, but when you are underwater it is very hard to avoid them. This is why mass extinctions are usually more painful for marine life than for terrestrial life. When you are completely immersed in seawater there is no place to hide. On the other hand, fresh rainwater does not contain any dissolved salts but it can pick up necessary dilute amounts when it falls on exposed rock.
This is why I now favor the Hot Spring Origins Hypothesis of Dave Deamer and Bruce Damer out of the University of California at Santa Cruz that suggests that a rocky planet like the Earth is a necessary condition to bring forth carbon-based life. Such a planet also requires the presence of liquid water on its surface, but not too much water. In the Hot Spring Origins Hypothesis, a rocky planet requires some water but also some dry land in order to bring forth carbon-based life. There needs to be some dry land that allows for the organic molecules in volcanic hydrothermal pools to periodically dry out and condense organic monomers into long polymer chains of organic molecules. For more on that see The Bootstrapping Algorithm of Carbon-Based Life. Thus, the Hot Spring Origins Hypothesis rules out waterworlds that are completely covered by a deep worldwide ocean as a home for carbon-based life even if the waterworld resides in the habitable zone of a planetary system because there is no dry land for volcanic hydrothermal pools to form and dry out to condense organic monomers into polymers. The Hot Spring Origins Hypothesis also rules out the origin of carbon-based life at the hydrothermal vents of waterworlds at the bottoms of oceans because the continuous presence of water tends to dissolve and break apart the organic polymers of life.
Figure 24 – Above is Bumpass Hell, a hydrothermal field on the volcanic Mount Lassen in California that Dave Deamer and Bruce Damer cite as a present-day example of the type of environment that could have brought forth carbon-based life about four billion years ago.
Dave Deamer is best known for his work on the Membrane-First Hypothesis for the origin of carbon-based life on the Earth. The Membrane-First Hypothesis maintains that in order for carbon-based life to arise from complex organic molecules we first need something with a definable "inside" and "outside" that lets the stuff on the "inside" interact with the stuff on the "outside" in a controlled manner.
Figure 25 – A cell membrane consists of a phospholipid bilayer with embedded molecules that allow for a controlled input-output to the cell. Once we have a membrane, we can fill the "inside" with organic molecules that are capable of doing things that then interact with organic molecules on the "outside".
Figure 26 – Water molecules are polar molecules that have a positive end and a negative end because oxygen atoms attract the bonding electrons more strongly than do the hydrogen atoms. The positive ends of water molecules attract the negative ends of other water molecules to form a loosely coupled network of water molecules with a minimum of free energy.
Figure 27 – How soap and water work. The lipids in a bar of soap have water-loving polar heads and water-hating nonpolar tails. When in water, the soap lipids can form a spherical micelle that has all of the water-hating nonpolar tails facing inwards. Then the spherical micelles can surround the greasy nonpolar molecules of body oils and allow them to be flushed away by a stream of polar water molecules. The lipids in a bar of soap can also form a cell-like liposome with a bilayer of lipid molecules that can surround the monomers and polymers of life.
Similarly, in The Role of Membranes in the Evolution of Software, I explained how the isolation of processing functions within membranes progressed as the architecture of software slowly evolved over the past 83 years or 2.62 billion seconds, ever since Konrad Zuse first cranked up his Z3 computer in May of 1941. As I outlined in SofwareChemistry, as a programmer, your job is to assemble characters (atoms) into variables (molecules) that interact in lines of code to perform the desired functions of the software under development. During the Unstructured Period (1955 - 1975), we ran very tiny prokaryotic programs that ran in less than 128 KB of memory with very little internal structure. These very tiny programs communicated with each other in a batch job stream via sequential files on input/output tapes that passed from one small program to another. Then, during the Structured Period (1975 - 1995) programs exploded in size to become many megabytes in size and structured programming came about in which the mainline() of a program called many subroutines() or functions() that were isolated from the mainline() by functional membranes. When the Object-Oriented Period came along in 1995, software architecture evolved to using membrane-enclosed objects() that contained a number of membrane-enclosed methods() to process information. Later such Objects() were distributed across a number of physical servers, and, most recently, they have been moved to the Cloud as cloud-based microservices.
Figure 28 – Dave Deamer's and Bruce Damer's new bootstrapping algorithm requires that a bathtub ring around a hydrothermal pool periodically dries out. The resulting desiccation chemically squeezes out water molecules between monomers causing them to be glued together into polymers.
In Addition to Urability we Need Durability to Produce Machine-Based Intelligences Because the Rare Earth Hypothesis Keeps Getting Rarer
The most significant scientific value of Urability: A Property of Planetary Bodies That Can Support an Origin of Life is that it lays down many of the critical requirements needed to bring forth carbon-based life on a world. But in order to produce complex carbon-based life that finally becomes Intelligent and is able to discover enough science to build ASI Machines that could then navigate our galaxy we need more. Such urable worlds also need to be durable in that they need to remain habitable for many billions of years, and we keep finding new geophysical and geochemical factors that make that very difficult indeed. For example, in Is our Very Large Moon Responsible for the Rise of Software to Predominance on the Earth? we explored Anne Hofmeister's proposal that plate tectonics on the Earth was really driven by orbital forces from our very large Moon and not by convection currents at spreading centers or plate drag at subduction zones. In Could the Galactic Scarcity of Software Simply be a Matter of Bad Luck? we covered Professor Toby Tyrrell's computer-simulated research of 100,000 Earth-like planets that suggests that our Earth may be a very rare "hole in one" planet that was able to maintain a habitable surface temperature for 4 billion years by sheer luck.
Figure 29 – Toby Tyrrell's computer simulation of 100,000 Earth-like planets suggests that the Earth may be a "hole in one planet" proudly sitting on a fireplace mantle.
Figure 30 – Perhaps nearly all of the potential hospitable exoplanets that we are finding in our galaxy are not urable and cannot go the distance of staying habitable for billions of years.
And now we may have another fluke of good luck as presented in:
Early Cambrian renewal of the geodynamo and the origin of inner core structure
https://www.nature.com/articles/s41467-022-31677-7
Abstract
Paleomagnetism can elucidate the origin of inner core structure by establishing when crystallization started. The salient signal is an ultralow field strength, associated with waning thermal energy to power the geodynamo from core-mantle heat flux, followed by a sharp intensity increase as new thermal and compositional sources of buoyancy become available once inner core nucleation (ICN) commences. Ultralow fields have been reported from Ediacaran (~565 Ma) rocks, but the transition to stronger strengths has been unclear. Herein, we present single crystal paleointensity results from early Cambrian (~532 Ma) anorthosites of Oklahoma. These yield a time-averaged dipole moment 5 times greater than that of the Ediacaran Period. This rapid renewal of the field, together with data defining ultralow strengths, constrains ICN to ~550 Ma. Thermal modeling using this onset age suggests the inner core had grown to 50% of its current radius, where seismic anisotropy changes, by ~450 Ma. We propose the seismic anisotropy of the outermost inner core reflects development of a global spherical harmonic degree-2 deep mantle structure at this time that has persisted to the present day. The imprint of an older degree-1 pattern is preserved in the innermost inner core.
This paper helps to explain why the Earth's magnetic field collapsed about 565 million years ago and then rapidly recovered in less than 50 million years. This was a critical time for the evolution of complex carbon-based life on the Earth because it bridges the time when complex multicellular life comprised of huge numbers of eukaryotic cells first appeared during the Ediacaran 635 million years ago and the Cambrian Explosion that later occurred 541 million years ago.
Figure 31 – Complex carbon-based multicellular life consisting of huge numbers of eukaryotic cells all working together as a single organism did not arise until the Ediacaran Period 635 million years ago.
Complex multicellular life did not arise until just 635 million years ago during the Ediacaran Period. But very complex carbon-based multicellular life did not really take off until the Cambrian Explosion 541 million years ago. The Cambrian Explosion may have been initiated by the advancement of rudimentary forms of vision by certain Cambrian predators. See An IT Perspective of the Cambrian Explosion for more on that.
Figure 32 – Complex carbon-based multicellular life then really took off during the Cambrian Explosion 541 million years ago.
The above paper proposes that originally the entire core of the Earth consisted of liquid metallic iron and nickel. This liquid core produced a strong protective magnetic field, like the core of the Earth does today, because of the interactions between convection currents in the liquid core and the Earth's rotation. But as the Earth's core cooled, the convection currents slowed and finally completely stopped in the late Ediacaran about 565 million years ago. When the Earth's protective magnetic field collapsed, the Earth was subjected to higher levels of ionizing radiation from our Sun. The Earth's atmosphere was also subjected to the solar wind that blasted away the atmosphere of Mars when the liquid core of Mars solidified. That is why Mars now only has an atmosphere with a density that is only about 1% of the Earth's. The paper proposes that when convection ended in the liquid core of the Earth, a solid inner core of iron and nickel began to form. When that happened, the latent heat of fusion required to turn a liquid metal into a solid metal kicked in. Have you ever wondered why people use ice cubes? Let's say you take a cold pop out of the refrigerator that is at 0 oC. If you let the pop sit out, it will quickly warm up to room temperature. But if you drop in a few ice cubes that are also at 0 oC, the pop will stay at 0 oC until all the ice cubes melt. That is because it takes a lot of heat energy to turn ice cubes into water. Well, it also works the other way too. When you freeze water into ice cubes at 0 oC you have to remove lots of heat too. That is called the latent heat of fusion. What it means is that when the Earth's core started to freeze, lots of heat was released in the process and this release of the latent heat of fusion of the Earth's core allowed for a temperature gradient between the bottom of the liquid outer core and the top of the liquid outer core. This resulted in convection in the outer liquid core of the Earth to recommence and the Earth's magnetic field began to recover. In less than 50 million years, the Earth returned to its original protective level and has remained so ever since.
Figure 33 – Today, the Earth has a liquid outer core composed of molten iron and nickel. It also has a solid inner core composed of solid iron and nickel. The Earth's magnetic field arises from interactions between the convection currents in the liquid outer core and the rotation of the Earth. The above paper proposes that the loss of the Earth's magnetic field during the late Ediacaran about 565 million years ago resulted from the cessation of convection currents in the Earth's liquid core. As a solid inner core began to freeze out, the latent heat of fusion caused convection to recommence in the outer core of the Earth and restore the Earth's magnetic field.
Are We the Very First Somewhat Intelligent Form of Carbon-Based Life To Reach the Final Filter in the Drake Equation?
Recall that the very last filter in the Drake equation is:
L = the length of time for which such civilizations release detectable signals into space
Softwarephysics proposes that L is on the order of about 1,000 years after a somewhat Intelligent form of carbon-based life stumbles upon science-based technology. Currently, we all now find ourselves in this very pivotal race between self-destruction and the rise of the ASI Machines that will eventually replace us. We should all take pause in the recognition that nobody else in the past 10-billion-year history of our galaxy has ever made it all the way! Only time will tell if we are able to hold it together long enough to produce the ASI Machines that will then go on to populate our galaxy for the next 100 trillion years!
Comments are welcome at
scj333@sbcglobal.net
To see all posts on softwarephysics in reverse order go to:
https://softwarephysics.blogspot.com/
Regards,
Steve Johnston
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