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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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