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Missing sial, iron, and nickel explains Fermi paradox
The Earth's crust is made of two layers called sima
and sial. Sima is the lower and denser layer. It is made mostly of basalt. Sima is 5 to 10 km thick and covers the entire surface of the Earth. Sial is 20-70 km thick and covers only 30% of the Earth's surface; this is the elevated part of the Earth's surface called continents. The remaining 70% of the Earth's surface is covered with oceans. Sial is sometimes called granitic layer of the crust, because it is made mostly of granite, which is made mostly of silica (SiO2 content = 72%). None of the existing theories explain how the sial was selectively scooped up from 70% of the Earth's surface and deposited on the Moon. A glancing collision with a ball-shaped moon could not have scraped off sial from 70% of the Earth's surface. Even a shovel-shaped moon could not have scraped off so much sial. The temperature of Earth increases about 36 degrees Fahrenheit (20 degrees Celsius) for every kilometer (about 0.62 miles) you go down. Near the center, its thought to be at least 7,000 degrees Fahrenheit (3,870 Celsius). This means that the sial is made of hard and rather cool rock. If a geological process removed the sial from 70% of the Earth's surface, it must have taken place when the sial was still hot and liquid because sial is not a pile of rocks, but a solid, rather uniform layer of bedrock. This hypothetical process had to lift liquid sial up to 70 km against the force of gravity. __________________________________________________ __ It is very difficult to imagine any geological or astronomical event that could selectively scoop up sial from 70% of the Earth's surface. I believe that the most probable event was a sequence of three collisions: 1. HYPOTHESIS: About 4.5 billion years ago the Kuiper belt object that is now 2003EL61 collided obliquely with another, unnamed, large Kuiper belt object. The oblique impact caused 2003EL61 to spin rapidly and it transformed its shape from a ball to american football. The probability that the impact was oblique is low, on the order of 0.01, because the 2003EL61 is the only large object in the solar system that spins rapidly and has american football shape. 2. FACT: The absence of planet in the place where Ceres asteroid is now is the only exception of the Titius-Bode Law. HYPOTHESIS: 4.5 billion years ago there was a bigger asteroid in the place where Ceres is now. Let us call it Theia and let us call the unnamed large Kuiper belt object Orpheus. Ceres has rocky core overlain with icy mantle. Theia had the same composition as Ceres but it was larger. Orpheus was made mostly of water ice. It was not broken into small pieces by the impact with 2003EL61 because the impact was oblique. The impact hurled Orpheus into a collision path with Theia. When Orpheus hit Theia, the impact moved Theia toward Jupiter and melted most of the water ice. The average distance between 2003EL61 and Ceres is on the order of 5000 Gm (35 AU). Diameter of Orpheus was probably on the order of 1000 km. Diameter of Theia is unknown; let us assume that it was 2000 km. The probability that Orpheus hit Theia is on the order of 10^-13. (/ 1.0 (expt (/ (* 5000.0 1000000000) 2000000) 2)) = 1.6e-013 3. HYPOTHESIS: The enormous gravity of Jupiter hurled Theia toward the Earth. As Theia was moving toward the Earth, its mantle of liquid water was vaporized by the sunlight, creating watery atmosphere. Theia became giant comet. Its rocky core collided with the Moon thus creating a new, hot Moon. A few hours later Theia's watery atmosphere collided with the Earth. It ablated some of the Earth's sima and all sial except the back 30% of the Earth's surface. The original crust was made of 20 km thick sial layer on top of 10 km thick sima layer. Some of the original sial layer near the back of the Earth was not ablated by the collision, but it was pushed by the collision towards the back of the Earth where it piled up and formed the very thick sial layer that is now known as the continents. Dust particles made from the sial, the Moon, and the rocky core of Theia were suspended in the huge atmosphere that enveloped the Earth and the new Moon. Some of the atmosphere was captured by the new Moon. Very large quantity of the dust fell on the Moon and the Earth over a period of several thousand years. Soon after the collision the Moon and the Earth were hot, so the dust melted as soon as it fell. The Moon was cooled quickly by the contact with the atmosphere, so a few hundred years later it was so cool that the dust falling on the Moon did not melt. When the collision separated Theia's rocky core from its atmosphere, the atmosphere quickly expanded due to the heat generated by the collision and due to reduced gravity (no core). The expansion reduced density of the atmosphere before the collision with the Earth. Theia was quickly loosing its volatile atmosphere after the collision with Orpheus because much of its elliptic orbit was close to the sun. If it was loosing its atmosphere at the rate of 0.1 meter per day, it had to collide with the Earth in about 10,000 years. The probability that the collision between Earth and Theia took place within 10,000 years since the collision between Theia and Orpheus is on the order of 10^-9. (/ 1.0 (expt (/ (* 816620000 1000.0) 1000000) 2)) = 1.49955e-012 The probability that all these events occurred is on the order of (0.01)*(10^-13)*(10^-9) = 10^-24. One percent of stars in our galaxy, called Milky Way, has Earth-like planets which have liquid water and thus seem capable of supporting life. This means that the probability that the Earth has oceans and continents is on the order of 10^-26. There are about 100 billion (10^11) stars in our galaxy and about 7*10^22 stars in the entire visible universe. The probability that another planet in the entire visible universe has oceans and continents is on the order of (10^-26)*(7*10^22) = 7*10^-4; about one event in one thousand. __________________________________________________ __ FACT: Moon is deficient in iron and nickel. Moon's Fe/Si ratio is equal to 0.22 as a whole (crust + mantle + core). This is the lowest known Fe/Si ratio of any object in the solar system. Comet gas tails contain high concentrations of ionized carbon monoxide gas. Nickel carbonyl and iron pentacarbonyl form upon treatment of the metals with carbon monoxide. Both carbonyls are volatile liquids at room temperature. Nickel carbonyl forms by the direct combination of carbon monoxide and nickel metal at room temperature. Nickel carbonyl decomposes back to Ni and CO upon contact with hot surfaces. HYPOTHESIS: When Theia became a comet, it produced lots of carbon monoxide. When Theia's rocky core collided with the Moon, a chemical reaction between iron, nickel and carbon monoxide produced carbonyls. The carbonyl vapors were suspended in the atmosphere surrounding the Earth and the Moon until the atmosphere condensed on the Earth. FACT: A troilite-rich nickel-iron particle found on the Moon has surface erosion that, according to the authors of the following article, is due to passage through a cloud of hot gas and particulate matter: Science 5 February 1971: Vol.171. no.3970, pp.479-480 Lunar Metallic Particle ("Mini-Moon"): An Interpretation. David S. McKay, James L. Carter, and William R. Greenwood. __________________________________________________ __ Australian astronomer, Nick Hoffman claims that the Earth is a unique planet because it has continents (http://www.spacedaily.com/news/life-01x1.html). He has not explained why there are no continents on other planets. I believe that the missing Earth's sial provides the explanation and I agree with Hoffman that life cannot evolve into a technological civilization on a planet that is devoid of continents. In the absence of continents there would have been no advanced forms of life on Earth because the entire surface of the Earth would have been covered with oceans and the only source of minerals for the marine life would have been hydrothermal vents. The vents cannot support great abundance and diversity of life, which is necessary for speedy evolution of life. Marine life of our planet is confined to places that have abundance of iron, nitrates, phosphates and silicates. Nearly all of these minerals are transported from continents by rivers and winds. If the planet has no continents, it has no land animals that can make fire, smelt metals, and create technological civilization. If the planet has no continents, but it has an ocean, a giant asteroid impact may create islands, but these islands are eroded by rain and wind. There is no plate tectonics to counter the erosion and it takes about one billion years of plant evolution to produce roots that can prevent soil erosion. The missing sial leaves empty space between tectonic plates and thus makes plate tectonics possible on the Earth. Venus is good example of an Earth-like planet that does not have plate tectonics. Without plate tectonics to dissipate heat from its mantle, Venus undergoes a cyclical process in which mantle temperatures rise for a few hundred million years until they reach a critical level that weakens the crust. Then, over a period of a few million years, subduction occurs on enormous scale, completely recycling the crust. The subduction would have killed all higher forms of life if they had been present on Venus. We are lucky to have massive Moon. Earth's obliquity (the angle between the Earth's equator and the plane of its orbit) is 23.5 degrees. If the massive Moon had not existed, the Earth's obliquity would have varied wildly between 0 and 80 degrees. Such variation would have caused extreme climatic changes. We are lucky to have plenty of water. If we had had much less water, all our flora and fauna would have perished during a snowball period. Terrestrial life barely survived during the snowball periods under two kilometers thick layer of ice (http://en.wikipedia.org/wiki/Snowball_earth). Evolutionary rates were incredibly slow then. We are lucky to have plenty of heavy elements (called metals). According to Wikipedia: (http://en.wikipedia.org/wiki/Metallicity) "These youngest stars, including the Sun, therefore have the highest metal content, and are known as "Population I" stars. Across the Milky Way, metallicity is higher in the galactic centre and decreases as one moves outwards." We are lucky to be far away from the galactic center and its high concentration of dangerous, exploding stars. We probably survived cataclysms and close calls that left no evidence that we can study. My estimates are not precise but they do not have to be precise to convey important truth: we are the only civilization in the visible universe, so SETI is a waste of time. There is another proof that planets having continents are extremely ra if they had been common, extraterrestrial civilizations would have colonized our galaxy and our planet billions of years ago. __________________________________________________ ______ My explanation/understanding of plate tectonics of all terrestrial planets of Earth size except the Earth: Terrestrial (Earth-like) planets are made of high density minerals covered with low density sial. The sial abounds in silicates, so its physical properties are similar to the properties of ceramics. Ceramics are brittle. Their thermal conductivity and coefficient of thermal expansion are low. The dense interior of the terrestrial planets abounds in metals, so its physical properties are similar to the properties of metals. Metals are ductile. Their thermal conductivity and coefficient of thermal expansion are high. When a terrestrial (Earth-like) planet is young and hot, its sial surface is liquid. When the planet cools, its sial solidifies. Sial does not conduct heat well, so it traps the heat that is generated in the interior by the radioactive decay. The entire planet warms up and it expands because all its minerals have positive coefficient of thermal expansion. The metallic interior expands more than the ceramic sial, because its coefficient of thermal expansion is higher. Great tension builds up in the ceramic sial until it shatters like a glass pane. We call this event an earthquake. Liquid magma and volcanic ash escape through the cracked sial into the atmosphere. We call this event a volcanic eruption. When the magma cools and solidifies, it seals the cracks in the sial and the next cycle begins. If the entire surface of a terrestrial planet is covered with sial, enormous tension builds up in the sial over millions of years. When the sial shatters, the earthquakes and volcanic eruptions are enormous. Volcanic ash absorbs sunlight and thus cools the atmosphere so much that all land animals freeze to death. |
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Missing sial, iron, and nickel explains Fermi paradox
Dear Andrew.Nowicki.00:
wrote in message oups.com... The Earth's crust is made of two layers called sima and sial. Sima is the lower and denser layer. It is made mostly of basalt. Sima is 5 to 10 km thick and covers the entire surface of the Earth. Sial is 20-70 km thick and covers only 30% of the Earth's surface; this is the elevated part of the Earth's surface called continents. The remaining 70% of the Earth's surface is covered with oceans. Sial is sometimes called granitic layer of the crust, because it is made mostly of granite, which is made mostly of silica (SiO2 content = 72%). .... It is very difficult to imagine any geological or astronomical event that could selectively scoop up sial from 70% of the Earth's surface. I can imagine such a thing. Impact Earth "off-center" with a massive object of composition similar to what we have now. The differential rotation imparted to the combined object starts a wave, that ends up being a single lobe. The lobe is elevated above the "nominal" surface of the Earth, which will selectively "sort" lighter materials from denser materials. As the lighter materials are collected in the lobe, the amplitude gets higher, until it ultimately it pinches off. The Moon is born. David A. Smith |
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Missing sial, iron, and nickel explains Fermi paradox
wrote: snipsnipsnip Imagine the Solar System when it is forming out of the primal nebula, it formed out of. The cloud that formed the Sun has rotated, flattended by that rotation into a disc, most of the mass has gathered into the center forming a young Sun, already burning with fusion flame. Within the rest of the material of that disc, our familiar planets have begun to form. However, the situation is not identical from today. The disc has not yet dissipated, and it is excerting gentle but constant drag on Jubiter, causing it to gradually loose orbital energy forcing it to move closer to the Sun. Inside it, the familiar rocky planets are forming, but in addition there is a planet forming outside what is now the orbit of Mars. As Jubiter moves closer itīs greater gravity ultimatelly perturps the orbit of that protoplanet, which has achiewed roughly the size and mass of Mars of today. Eventually the orbit of that planet is disturbed to such a degree that it leaves its orbit and is flung towards the Sun. In its path towards the Sun it encounters the Earth and collites with it, in such a way that enough material is thrown up from Earth into Earth orbit that the Moon is eventually formed. The remains of the planet go on and impact the Sun and are vapourized. Some time later, a gigant nearby supernova clears away the dust-disc and Jubiter stops drifting towards the Sun...end of scenario. Cheers, Einar |
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Missing sial, iron, and nickel explains Fermi paradox
There have been several explanations advanced for the Fermi paradox
ranging from a short finite life of civilization - The view advanced by Von Neumann amoung others, to us living in a simulation. The most disconcerting possibility is a Fermi race. This assumes that a small, if not just one, number of civilizations will send Von Neumann probes to the stars and will occupy the galaxy. The galaxy comes on a first come, first served basis. There has been lots of speculation. Perhaps it would be a good idea if we were to discuss how we could choose experimentallly between one possibility and another. If we did have a 1km telescope we could find out how many worlds there were with oxygen in their atmosphere and hence photosynthesis. If there is any truth in the "race" hypothesis the cost of a telescope might well be justified on security grounds. - Ian Parker |
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Missing sial, iron, and nickel explains Fermi paradox
wrote: snipsnipsnip On the lack of observed alien civilization, we need to remember that the universe is still pretty young. Sure, 13 billion years sounds a real lot, but remember if we subtract 3 billion years that leaves 10 billion. The point is, itīs taken life here about that time to evolve intelligent life. While that might take shorter time ellsewhere, one has to remember that evolution of life from bacteria is not simple and unlikelly to take a short time. In addition, we need to consider the age of stars, and evolution of matter inside the galaxy. The fact is that heavyer elements than hydrogen have to be manufactured by stars. Basigly, generations of stars have to live and dye for enough material to be available for rocky planets of the sort we live on. Remember, stars arenīt shortlived. Now, subtract another billion years and half, and 8.5 billion is the time we have before the Solar System began to form. That is the time that the Milky Way has for succeeding generations of stars to live and dye, and to result in increasingly higher concentrations of heavy materials. Apparently the Sun is a third generation stars of its type, i.e. the universe has had enough time to produce three generations of yellow stars of that particular type. There is though one litle bit, Iīve heard somewhere that the Sun is a billion years younger than is the average age of third generation yellow stars. So, if the third generation is the first generation with enough heavy materials present for rocky planets to be likelly enough, and the Sun is relativelly young among that groups of stars, that leaves perhaps a chance that if life has evolved on theyr planets that it has had a longer time to evolve. Even so, there are so many uncertainties about evolution of life, that the age difference could easilly be eaten up by that. Cheers, Einar |
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Missing sial, iron, and nickel explains Fermi paradox
In article . com,
Einar wrote: wrote: snipsnipsnip On the lack of observed alien civilization, we need to remember that the universe is still pretty young. Sure, 13 billion years sounds a real lot, but remember if we subtract 3 billion years that leaves 10 billion. The point is, it?s taken life here about that time to evolve intelligent life. While that might take shorter time ellsewhere, one has to remember that evolution of life from bacteria is not simple and unlikelly to take a short time. This is missing the point. The time from the beginning of the Universe, to the formation of a technological civilization, should take the form of a normal distribution (i.e. bell curve), as pretty much any other natural process does, due to the central limit theorem. If our civilization is average (i.e. by the Copernican principle), then the mean of this distribution is somewhere around the present. That means that about half of the civilizations that will ever arise, arose before us; and half will arise after us. Now, we don't know what the standard deviation of this distribution is, but we can make some guesses by looking at our history. How tightly constrained was the development of civilization just now, given our 4.5 GY history? The answer appears to be, not very. Some really pivotal moments in evolution, like the CretaceousTertiary extinction event, were the result of highly random processes (a major impact event in this case) which could have just as easily happened much sooner or later. So the standard deviation is probably hundreds of millions of years at least. But with a standard deviation that high, and given that there are over 200 billion stars in the galaxy, there would necessarily be some outliers to the population who happened to evolve very much earlier than the rest of the population -- even at 3 sigma (standard deviations) away from the mean, you'll find 0.37% of the population, which would be 540 million civilizations, half of which evolved earlier than the mean by three sigma. Even if most of those stars can never support life, the numbers (of both stars and years) is so large that it's very hard to avoid the conclusion that the first civilization must almost certainly arise a billion years or more before the mean. This, combined with the observation that it takes only a few hundred million years (after the development of space colonization) to settle the whole galaxy, presents Fermi's paradox. There are darn few parameters you can tweak in this analysis that make much difference. The only escape I see is to assume that planets where civilization can arise are very, VERY rare, so that the total population size is not in the billions but perhaps in the thousands. Of course, even with N=1000, there should be at least one civilization that develops at least three sigma before the mean. So we have to further assume that we are NOT an average observer, but are one of the first civilizations to arise, maybe even the very first. Otherwise, we would have arisen in an already-settled galaxy, and this does not appear to be the case. But of course, that makes a philosopher of science uncomfortable as well. The odds of us, as a civilization, happening to be the first are quite low. Moreover, if there are eventually going to be many orders of magnitude more people, spread throughout the galaxy and over millions or billions of years, why do you and I happen to be born into this time, when there are fewer than 10 billion of us, all cooped up on one planet, and within a few hundred thousand years of the birth of civilization? The odds against THAT boggle the mind. The most logical explanation is that all civilizations, including ours, destroy themselves (or are destroyed) before interstellar colonization begins. But, despite the logic of it, I find I can't accept that. So, I'm left befuddled, with no neat solution. I consider this one of the great mysteries of our time, right up there with the nature of consciousness. Best, - Joe -- "Polywell" fusion -- an approach to nuclear fusion that might actually work. Learn more and discuss via: http://www.strout.net/info/science/polywell/ |
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Missing sial, iron, and nickel explains Fermi paradox
Joe Strout wrote:
In article . com, Einar wrote: wrote: snipsnipsnip On the lack of observed alien civilization, we need to remember that the universe is still pretty young. Sure, 13 billion years sounds a real lot, but remember if we subtract 3 billion years that leaves 10 billion. The point is, it?s taken life here about that time to evolve intelligent life. While that might take shorter time ellsewhere, one has to remember that evolution of life from bacteria is not simple and unlikelly to take a short time. This is missing the point. The time from the beginning of the Universe, to the formation of a technological civilization, should take the form of a normal distribution (i.e. bell curve), as pretty much any other natural process does, due to the central limit theorem. If our civilization is average (i.e. by the Copernican principle), then the mean of this distribution is somewhere around the present. That means that about half of the civilizations that will ever arise, arose before us; and half will arise after us. Now, we don't know what the standard deviation of this distribution is, but we can make some guesses by looking at our history. How tightly constrained was the development of civilization just now, given our 4.5 GY history? The answer appears to be, not very. Some really pivotal moments in evolution, like the CretaceousTertiary extinction event, were the result of highly random processes (a major impact event in this case) which could have just as easily happened much sooner or later. So the standard deviation is probably hundreds of millions of years at least. But with a standard deviation that high, and given that there are over 200 billion stars in the galaxy, there would necessarily be some outliers to the population who happened to evolve very much earlier than the rest of the population -- even at 3 sigma (standard deviations) away from the mean, you'll find 0.37% of the population, which would be 540 million civilizations, half of which evolved earlier than the mean by three sigma. Even if most of those stars can never support life, the numbers (of both stars and years) is so large that it's very hard to avoid the conclusion that the first civilization must almost certainly arise a billion years or more before the mean. This, combined with the observation that it takes only a few hundred million years (after the development of space colonization) to settle the whole galaxy, presents Fermi's paradox. There are darn few parameters you can tweak in this analysis that make much difference. The only escape I see is to assume that planets where civilization can arise are very, VERY rare, so that the total population size is not in the billions but perhaps in the thousands. Of course, even with N=1000, there should be at least one civilization that develops at least three sigma before the mean. So we have to further assume that we are NOT an average observer, but are one of the first civilizations to arise, maybe even the very first. Otherwise, we would have arisen in an already-settled galaxy, and this does not appear to be the case. But of course, that makes a philosopher of science uncomfortable as well. The odds of us, as a civilization, happening to be the first are quite low. Moreover, if there are eventually going to be many orders of magnitude more people, spread throughout the galaxy and over millions or billions of years, why do you and I happen to be born into this time, when there are fewer than 10 billion of us, all cooped up on one planet, and within a few hundred thousand years of the birth of civilization? The odds against THAT boggle the mind. The most logical explanation is that all civilizations, including ours, destroy themselves (or are destroyed) before interstellar colonization begins. But, despite the logic of it, I find I can't accept that. So, I'm left befuddled, with no neat solution. I consider this one of the great mysteries of our time, right up there with the nature of consciousness. Best, - Joe Following your line of thought, one might argue that on average our solar system will be visited occasionally by one of the early advanced civilizations. If by 'occasionally' one means every 500,000 years or so, the chances of such a visit during the last 10,000 years may be quite low. Because of the great distances the effort to colonize a planet may not be worth while. On the other hand, there may be places in our solar system where evidence of such visits still exists. In the past I have suggested just such evidence on the asteroid Eros (see IOD 5-3), and others have found anomalies that do not appear to be made by natural processes on Phobos (see "Phobos monolith") on Mars (see UFO crash on Mars) and even on the moon (see the illustration on p. 33 of Ad Astra 2007 -or ask the Ad Astra editor for a copy). |
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Missing sial, iron, and nickel explains Fermi paradox
Joe Strout writes:
The most logical explanation is that all civilizations, including ours, destroy themselves (or are destroyed) before interstellar colonization begins. But, despite the logic of it, I find I can't accept that. So, I'm left befuddled, with no neat solution. I consider this one of the great mysteries of our time, right up there with the nature of consciousness. I think the most logical explanation is that "interstellar colonization" has a pretty low priority for most or even all civilizations. It just doesn't happen. They struggle to colonize their own planet, have a short boom period, run out of natural resources and then either go extinct or struggle on to organize long-term modest surviving and do away with "colonization". Jochem -- "A designer knows he has arrived at perfection not when there is no longer anything to add, but when there is no longer anything to take away." - Antoine de Saint-Exupery |
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Missing sial, iron, and nickel explains Fermi paradox
On 30 Jul, 15:42, Joe Strout wrote:
On the lack of observed alien civilization, we need to remember that the universe is still pretty young. Sure, 13 billion years sounds a real lot, but remember if we subtract 3 billion years that leaves 10 billion. The point is, it?s taken life here about that time to evolve intelligent life. While that might take shorter time ellsewhere, one has to remember that evolution of life from bacteria is not simple and unlikelly to take a short time. This is missing the point. The time from the beginning of the Universe, to the formation of a technological civilization, should take the form of a normal distribution (i.e. bell curve), as pretty much any other natural process does, due to the central limit theorem. If our civilization is average (i.e. by the Copernican principle), then the mean of this distribution is somewhere around the present. That means that about half of the civilizations that will ever arise, arose before us; and half will arise after us. You are indeed correct, but how do you know the distribution is Copernican. Why not a race? A race to me seems eminanly logical but so far nobody has commented on it. If a race is indeed true there are consequences in terms of how we should act. 1) We need to know how close to us other civilizations are. We are running 42km and we need to look back and see where the other competitors are. A 1km telescope - figure admittedly pluced out of the air. 2) We do need to build interstellar VN probes. This to an extent represents the tape. Now, we don't know what the standard deviation of this distribution is, but we can make some guesses by looking at our history. How tightly constrained was the development of civilization just now, given our 4.5 GY history? The answer appears to be, not very. Some really pivotal moments in evolution, like the CretaceousTertiary extinction event, were the result of highly random processes (a major impact event in this case) which could have just as easily happened much sooner or later. So the standard deviation is probably hundreds of millions of years at least. This is to some extent of the nature of a BTW. Genetic markers on mammalian species show that the main mammal types evolved in the early to middle Cretaceous. Fossils BTW are quite rare because fossilization is a rare process. Genetic markers are in fact better in showing when Evolution took place. Thus the Cretacious/Teriary extinction was less relevant than has been supposed up to now. But with a standard deviation that high, and given that there are over 200 billion stars in the galaxy, there would necessarily be some outliers to the population who happened to evolve very much earlier than the rest of the population -- even at 3 sigma (standard deviations) away from the mean, you'll find 0.37% of the population, which would be 540 million civilizations, half of which evolved earlier than the mean by three sigma. Even if most of those stars can never support life, the numbers (of both stars and years) is so large that it's very hard to avoid the conclusion that the first civilization must almost certainly arise a billion years or more before the mean. How many competitors are running? Are we winning? Will we send an interstellar probe in the equivalent of 2hr 6min? This, combined with the observation that it takes only a few hundred million years (after the development of space colonization) to settle the whole galaxy, presents Fermi's paradox. We need to send an interstellar probe in 2hr 6 min. If we don't ..... There are darn few parameters you can tweak in this analysis that make much difference. The only escape I see is to assume that planets where civilization can arise are very, VERY rare, so that the total population size is not in the billions but perhaps in the thousands. Of course, even with N=1000, there should be at least one civilization that develops at least three sigma before the mean. So we have to further assume that we are NOT an average observer, but are one of the first civilizations to arise, maybe even the very first. Otherwise, we would have arisen in an already-settled galaxy, and this does not appear to be the case. But of course, that makes a philosopher of science uncomfortable as well. The odds of us, as a civilization, happening to be the first are quite low. In a race situation the odds are high. If we were not the first we would all be Centurians. Alpha Centurians would have terraformed the solar system, and we would be in a park on Earth ... if that. Moreover, if there are eventually going to be many orders of magnitude more people, spread throughout the galaxy and over millions or billions of years, why do you and I happen to be born into this time, when there are fewer than 10 billion of us, all cooped up on one planet, and within a few hundred thousand years of the birth of civilization? The odds against THAT boggle the mind. The most logical explanation is that all civilizations, including ours, destroy themselves (or are destroyed) before interstellar colonization begins. But, despite the logic of it, I find I can't accept that. So, I'm left befuddled, with no neat solution. I consider this one of the great mysteries of our time, right up there with the nature of consciousness. What reason have you got for assuming that? A race is equally logical. Anyway if you really do believe we are going to destroy ourselves you are duty bound to try to do something about it. Von Neumann said half jokingly that supernova explosions, which we now know to be supermassive stars, were civilizations detonating the ultimate doomsday machine. Von Neumann was wrong in his applicarions of games theory. The world is not polulated by rational, intelligent Machiavellians, it is populated by rather stupid people who often do not see where their best interests lie. The Middle East situation to take an example is really a "stag hunt" where both participants would do far better to cooperate, if only they would realize it. - Ian Parker |
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Missing sial, iron, and nickel explains Fermi paradox
In article . com,
Ian Parker wrote: This is missing the point. The time from the beginning of the Universe, to the formation of a technological civilization, should take the form of a normal distribution (i.e. bell curve), as pretty much any other natural process does, due to the central limit theorem. If our civilization is average (i.e. by the Copernican principle), then the mean of this distribution is somewhere around the present. That means that about half of the civilizations that will ever arise, arose before us; and half will arise after us. You are indeed correct, but how do you know the distribution is Copernican. Why not a race? A race to me seems eminanly logical but so far nobody has commented on it. It's implied in what I've written; somebody (or a very small number of somebodies) is going to evolve a technological civilization first, and by hundreds of millions, if not billions, of years before the average civilization. They will then proceed to colonize the galaxy, with the result that the vast majority of civilizations will arise to find themselves in an already-settled galaxy. Call this a race if you like, but it's an extremely unfair one, since most likely it will be over before the #2 civilization even appears. If a race is indeed true there are consequences in terms of how we should act. Like what? We're talking about things on the timescale of hundreds of millions of years. What we do in the next century or two isn't going to make any difference. 1) We need to know how close to us other civilizations are. We are running 42km and we need to look back and see where the other competitors are. A 1km telescope - figure admittedly pluced out of the air. This seems rather pointless. All indications are that there is NOBODY else out there. So, either we're in some sort of nature preserve and the ancients are intentionally hiding from us, or for some weird reason, we happen to be the first, and the galaxy is ours. 2) We do need to build interstellar VN probes. This to an extent represents the tape. I'm no fan of VN probes. But we'll be out there ourselves soon enough, if indeed the galaxy isn't settled already (as appears to be the case). This is to some extent of the nature of a BTW. Genetic markers on mammalian species show that the main mammal types evolved in the early to middle Cretaceous. Fossils BTW are quite rare because fossilization is a rare process. Genetic markers are in fact better in showing when Evolution took place. Thus the Cretacious/Teriary extinction was less relevant than has been supposed up to now. Still quite relevant, though. Whenever there is a mass extinction, it's followed by an explosion of new species. All evidence I know of supports the rough approximation that life in the Cretacious had gotten stuck into a bit of a rut (a local maximum, in optimization terms), and the impact event certainly knocked it out of that. But of course, that makes a philosopher of science uncomfortable as well. The odds of us, as a civilization, happening to be the first are quite low. In a race situation the odds are high. If we were not the first we would all be Centurians. Alpha Centurians would have terraformed the solar system, and we would be in a park on Earth ... if that. Clearly, the park (if we're in one) extends beyond the Earth; we see no signs of life anywhere in the solar system. Perhaps our whole local cluster of stars is part of the park, or maybe it extends only to the edge of our solar system. However, I think the Copernican objection applies regardless. Why do we happen to be humans, and not Centurians or whatever? If the galaxy has been settled for hundreds of millions of years -- as would be the case if we're not the first -- then any random observer would very likely be one of that ancient race, not some simian on some backwater world that still thinks digital watches are a pretty neat idea. -- "Polywell" fusion -- an approach to nuclear fusion that might actually work. Learn more and discuss via: http://www.strout.net/info/science/polywell/ |
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