Birth of the Universe: Science and Religion

1. Birth of the Universe: Science and Religion About 15 billion years have passed since the Big Bang. The Universe has been expanding for that amount of time. Since then stars have come and gone and new stars form every day. The flash of intense radiation at the Big Bang has cooled to 3 degrees above absolute zero, and the wavelength has increased to 2mm. The original photons are still around and you can see them on your tv by tuning to a blank channel and turning the brightness down until it is almost dark. One percent of the bright specks you see are primordial photons! The other 99% are communication microwave noise. You can catch the moment of creation in your living room! The events that followed the Big Bang are amazingly orderly. The formation of hydrogen and helium in their proportions is a consequence of the initial bang. Also inescapable is the formation of stars, and the formation of heavier elements within them, their dispersion to outer space during supernova explosions, the formation of more stars, and the formation of planetary systems, including planets like the Earth. Given a planet like Earth as a substage, it is virtually impossible to prevent life from evolving. Thus, through a series of steps (logical and probable), we end up with intelligent life. Those who are familiar only with the final product--Earth and life as they appear today--find this product so astonishing in its complexity that they have to invoke a Higher Power to have made it and run it. “Out of this primordial need to explain the existence of our world has come religion, in all of its multifaceted, often contradictory, and even absurd manifestations.” Cesere Emiliani If we look at the world through time, everything seems to have evolved necessarily and inevitably, from simple to complex, from primaeval fireball to our modern civilization. Unfortunately, there was no one around to observe and record notes. The Babylonians and Egyptians were amongst the first and best of the early observers and recorders. One of the early questions was “how did this world come about”? The earliest tradition on origins arose in India around 2000BCE (maybe much earlier) and was codified in the Rig-veda (1200BCE). According to this tradition, in the beginning, there was the One, who breathed by its own energy. Then desire entered the One and Thought was created. From that came light, and then all the rest. According to the biblical tradition, as written in Genesis (ca. 1250BCE), “In the beginning God made heaven and earth, but the earth was invisible and featureless and darkness [was] on the abyss, and the breath of god was carried over the waters; and God said “let there be light” and light came into being”. The creation of light made it possible to distinguish between night and day and established the first formal day. During the next five days, God made everything else as follows… Genesis according to Hesiod (750BCE) In the beginning, there was Chaos (empty space). Day 1: Light (day and night) Next came Gaia (Earth), Tartarus (the underworld), and Eros (love). Day 2: The sky, separating the water “below” from that “above” Day 3: Water under the sky gathered into a basin (sea), letting dry land emerge (earth); trees on land, with fruits and seeds. Day 4: Sun, moon, stars Day 5: Marine animals and birds Day 6: Wild animals, cattle, reptiles, man and woman Day 7: Day of rest Thus, the jews make the world in a simple, nearly logical way in six days. The Greeks had a very different way of looking at things. Gaia was lonely and produced Uranus (heaven), known as Saturn by the Romans. In union with Uranus, Gaia gave birth to 12 Titans (including Oceanus, Rhea, and Cronos, the youngest child), 3 cyclops, and 3 Hekatoncheirontes (monsters with 100 arms and 50 heads each). When Uranus saw these monsters, he got mad and tried to stuff them back inside Gaia. Gaia didn’t like this move and gave Cronos a flint knife, and told him to castrate Uranus.

2. Genesis according to Hesiod (750BCE) Cronos did as he was told and threw Uranus’ testicles into the Aegean Sea. The sea foamed around the testicles and out of the foam rose the island of Cyprus, with Aphrodite (Venus) nude on the beach. Hermes Ares Hephaistos Genesis according to Hesiod (750BCE) Zeus also produced Athena (Minerva) out of his head when Hephaistos split it with an ax to cure him of a headache. Zeus made the present human race. It is a race of evil people who despise the good and praise the bad. Zeus destroyed it with a flood, except for Deucalion (his cousin) and Deucalion’s wife Pyrrha. The couple built a boat and floated around on it for nine days and nights, eventually landing on Mount Parnassos. The two repopulated the Earth by throwing stones behind their backs--Deucalion’s stones became men and Pyrrha’s became women. Uranus predicted to Cronos that his own children would unseat him. Cronos forced his sister Rhea to bear him Hestia (Vesta), Hera (Juno), Poseidon (Neptune), and Hades (Pluto), but each time a child was born, Cronos sneaked into the nursery, and swallowed it. When the last child, Zeus, was born, Rhea hid him in a cave on Mount Ida in Crete and put a stone in the crib. Cronos sneaked in and swallowed the stone. That made him vomit, and he not only vomited the stone but also all the children he had previously swallowed. Zeus grew up, drove the Titans out of heaven into Tartarus. He then proceeded to father Apollo and Artemis (Diana) in union with Leto (daughter of two Titans). Hermes (Mercury) in union with Maia (daughter of two other Titans); and Ares (Mars) and Hephaistos (Vulcan) in union with Hera (Juno). Rhea Zarathustra Buddha Lao-tzu Confucius During the sixth and fifth centuries BCE Asia was shaken by religious innovation. The Rig-veda evolved into Hinduism and great religious leaders appeared--Zarathustra in Media (628 BCE), Buddha in India (ca. 563-483 BCE), and Lao-tzu (ca. 604-531 BCE) and Confucius in China (ca. 551-479 BCE). Later Jesus (4~7 BCE to 33 CE) (Most theologians and religious historians believe that the approximate birth date of Yeshua of Nazareth was in the fall, sometime between 4 and 7 BCE)and Muhammad (ca. 570-630 CE) gave rise to two great religions based on the biblical tradition: Christianity and Islam. None of these Asiatic religions showed much interest in natural phenomena. Apollo Artemis Zeus

3. The Greeks on the other hand, not only created a religion that attempted to explain natural phenomena but also went on to interpret and hypothesize. Greek religion soon grew into such a strange tangle of stories that some people began to become skeptical. Questioning, thinking and probing by these skeptics led to the origin of western thought…2,500 years later here is our story. How long did this singularity last? The question is meaningless: if time does not flow, an eternity, or no time at all is all the same. What does seem certain though is that this situation is unstable and has to blow up. For the first 3 x 10-10 seconds, temperature was too high for matter to be stable, only radiation would be stable. This first period of cosmic time is known as the Planckian. The Planckian is defined by the time it took light to travel the Planck length (=1.616 x 10-35m). Because we don’t even know if our fundamental constants operated during this period, nothing is known about the Planckian. We’re just not sure how realistic our ideas are. The Universe Cosmology is the oldest science that we know of. All civilizations from the most ancient to the most modern make and record observations of objects in the sky and their behavior, usually very accurately. The positions of the planets were recorded against the backdrop of stars that never seemed to change. These stars formed a perfect grid to detect planetary motion. It was interest in the motion of the planets that first led people to think that these bodies determined human events--thus ancient astronomy was really astrology. That being said, how did the universe begin? The Planckian (0 to 5.390 x 10-44 s) was followed by the Gamowian, the second aeon of cosmic time, about which we know quite a bit. The Gamowian ranges from 5.390 x 10-44 s after time zero to 4.6 billion years ago, when the solar system formed. It is the longest aeon in cosmic time. During this time the universe has been expanding. The rate of expansion has been either increasing, constant, or decreasing. An increasing or constant rate leads to an open universe-- a universe that will keep expanding forever. A decreasing rate may lead to a finite radius (a flat universe) or it may decrease to zero and then reverse itself. In the latter case the universe is closed and will fall back on itself and eventually collapse in a cosmocrunch. The Hubble Telescope's deepest view of the universe teaches us about the beginning. Expansion Expansion involves the continuous creation of space between celestial objects that are not sufficiently bound to each other gravitationally, namely galactic clusters. It is the space between galactic clusters that increases with time, not the distance between one galaxy and the next or the distance between stars within a galaxy. During the earliest Gamowian, the four forces of nature were part of a single “superforce.” In order for this to make sense, consider gravity to be the weakest of the four forces of nature. The mass of a particle increases with increasing speed such that the mass of even the smallest particles would reach infinity if the particle could be accelerated to the speed of light. How and when did the universe come into existence? We do have an idea of the when (between 10 and 20 billion years ago), but the how is much more difficult to discuss. The universe is now expanding. If it is closed (i.e. its density is greater than 6.5 x 10-30 g/cm3 (which we do not yet know), it will slow down, stop and then collapse (like Enron) about 100 billion years later. All particles will collapse into a singularity. A point of extremely high (perhaps infinite) density and extremely high (perhaps infinite) temperature. Space itself may collapse into that point. Inside that point, matter and energy will be indistinguishable. This point contains all the matter and energy of the universe, around which there may have been no space and no time would pass. At the very high temperatures (>1031 K) prevailing at time t = 10-43 s, the mass of the particles was so large (because of their speed) that the gravitational force between the particles was as strong as the strong force. The other two forces, the electromagnetic and weak force which are intermediate in strength between gravity and the strong force, follow suit. As a result, above 1031 K, the four forces are indistinguishable. As the universe expanded, temperature decreased, which caused the mass of the particles to decrease and gravitational interaction to weaken. Gravity was therefore the first force to appear as a separate force. Next to separate was the strong force, followed by the electroweak force (which quickly split into the electromagnetic force and the weak force).

4. According to current theory, a period of inflation occurred between 10-33 and 10-32 s, during which time the radius of the universe grew from 10-33 light-seconds (=3 x 10-25m) to 10 cm. The increase in radius from practically zero to 10 cm in 9 x 10-33 seconds resulted in a speed of radial expansion of 1032 m/s. This is 3 x 1023 times faster than the speed of light! So, what’s the problem here? Relativity was not violated because inflation did not involve transmission of signals or information, only an increase in space. What’s so special about that? 2. The average amount of matter in space is the same everywhere on a large enough scale (a cubic billion light-years) but is irregularly distributed on a smaller scale (forming stars, galaxies, galactic clusters, and filaments). Thermal equilibrium across the earliest universe suggests that radiation density was also uniform, except for exceedingly minute random fluctuations. As a result, when matter condensed out of this radiation, its distribution on a large scale in space was also uniform. The minute, random density fluctuations were magnified by inflation to form small-scale fluctuations in the density of matter, which resulted in the accumulation of stars and galaxies. In the standard model, magnification would be far too slow to account for the stars and galaxies that we see around us. 3. Certain massive particles called monopoles seem to be missing. The greatest distance at which a point inside a 10-cm sphere could see would be only 3 x 10-24 m, the maximum distance that light could travel within the 10-32 seconds since the beginning. The volume of a spherule with a radius of 3 x 10-24 m is 1.1 x 10-70 m3, while the volume of the 10-cm sphere is 4.2 x 10-3 m3. This sphere therefore contains 4.2 x 10-3/1.1 x 10-70 = 3.8 x 1067 spherules. According to the inflation theory, the larger sphere, and all the spherules inside it, have since expanded, until our spherule has reached its present radius of 15 billion light-years. This is what we call the visible universe. All the other spherules have also expanded and become universes of their own, within which objects are in mutual, visible contact. Monopoles are massive particles consisting of individual N or S magnetic poles. According to theory, monopoles should have formed in great numbers in the early universe, but they are not seen today, even though they should be readily detectable because of their large mass. The inflation model says that there should be as many as 1067 different universes, so that one universe may contain only a few monopoles. This would make their discovery very difficult if not impossible. 4. Flatness of the universe The average density of matter in the universe (0.9 x 10-30 g/cm) is really close to the limit between an open (expands forever) and closed (stops expanding and collapses) universe. The early universe was ultradense, and therefore its space-time would be highly curved. The enormous inflation that took place “flattened out” space-time just like a balloon flattens out its surface, bringing the average density of the universe close to the critical value. This means that our universe is only one of 3.8 x 1067 other universes that we will never be able to see, or know anything about, because they started out too far apart from us, within the original sphere for their light to ever reach us. As the story goes, after 10-32 s, the inflated universe resumed its expansion at the rate given by the Hubble constant. Why do we need all of this complicated multi-universe stuff?! 5. The universe contains matter and not just radiation. Turns out that we need it to explain some things… Between the end of the Planckian and inflation, matter and antimatter briefly appeared, but were unstable at those high temperatures. When the universe inflated, temperatures dropped and energy was converted into both matter and antimatter which could now remain stable. Matter and antimatter readily change into each other, but the reaction of antimatter to matter is slightly favored. In fact 109 + 1 quarks were created for every 109 antiquarks. Quarks and antiquarks did not stabilize until time t = 5 x 10-6 s, when temperature dropped below 3 x 1012 K. At that time nearly all matter and antimatter had converted back into radiation, with only one particle in a billion surviving (this explains the observation that the ratio of material particles to photons in the visible universe is 1/109). The matter that survived forms all the objects we can see in the universe. The spectrum of microwave radiation that pervades the universe today is the same in all directions. This implies that the earliest universe had the same temperature everywhere. Distant regions of the universe whose light is just now reaching us have been cut off from each other since the beginning of time. Because the universe started expanding immediately at t = 0, there was no time to reach thermal equilibrium. The inflation model says that between t = 0 and t = 10-35 s the universe was small enough for light to reach across it and ensure thermal equilibrium. This is similar to why you don’t heat pizza on high in a microwave if you want it heated evenly. The water in the sauce heats before the rest and will boil in your mouth.

5. When the temperature dropped to below 1012 K, 2H became stable, and at 1010 K 3H and 4He nuclei and electrons became stable…at that was the end of matter formation because 5He is incredibly unstable preventing any heavier elements from forming. This scenario is the result of calculations rather than guesswork which is why we observe a universe of stars and interstellar material made of 74% H and 26% He. Stars The Sun and other common stars produce energy by two processes: proton-proton chain and the carbon cycle. The proton-proton chain requires a temperature of ≈ 15 x 106 K to take place. The carbon cycle requires a higher temperature, because it takes more energy to ram a proton into a carbon nucleus (which contains 6 protons) than attach it to another proton. In the Sun, 91% of the energy is produced by the proton-proton chain and the rest by the carbon cycle. Stars that are more massive than the Sun have higher core temperatures and produce energy mainly by the carbon cycle. When the temperature decreased to about 3000 K at 800,000 years after the Big Bang, the energy was low enough for atoms to become stable. Until then, electrons were free to roam about making the universe look like a luminous fog (like a neon sign). Stars are formed when a diffuse, cold gas cloud is shocked into collapsing by a passing shockwave (usually a supernova). When a cloud collapses, heat is generated as matter falls inward, and the shrinking cloud begins to rotate faster and faster in order to conserve angular momentum. The rapid rotation forces some of the material of the original cloud to form a disc rotating around the central body. When the temperature reaches 107 K, the proton-proton chain starts and the star is born. As hydrogen is used up, the star shrinks and heats up. A middle-sized star like our Sun will heat from 15 to 100 million K. The energy buildup is too fast to radiate away and the star expands 100-fold. In the case of our Sun, the surface will reach between Mercury and Venus. Once the electrons were captured, the universe became transparent to radiation but there was nothing to see because density had decreased to 1.6 x 10-17 g/cm3 and there were no stars yet. There are details that still need work, but scientists are fairly confident that the observations match the predictions. Furthermore, the Titus-Bode law which states that planetary distances from the central body are not random, a planet like Earth is likely to exist in most if not all, planetary systems! In fact, if one does the calculations, it is likely that there are 0.8 x 1021 planets like Earth in the visible universe. Now for some bad news… Luminosity increases but the temperature decreases to about 3000 K. Our Sun has therefore become a Red Giant. This will happen in about 5 billion years. The Earth’s temperature will rise, water will vaporize, and the atmosphere will blow away, destroying all life. Some Red Giants expand and contract with periods ranging from less than 1 to 100 days. The collapse of the core raises its temperature to 108 K, which is high enough for two 4He nuclei to combine to form 8Be which has a half-life of only 10-16 s, but in the dense core, a third 4He may collide and produce a 12C. In our Sun, this phase will last about a billion years. The average age of a star like the Sun in the visible universe is probably similar to the Sun (5 x 109 y). The human brain achieved its present size 125,000 years ago. Assuming that Homo sapiens will soon be extinct, the average window for intelligent life is = 125,000 y/5 x 109 y =2.5 x 10-5 Assuming that each planet has the same population as Earth (5 x 109 people), we have: Number of people in the visible universe = (0.8 x 1021) x (5 x 109) x (2.5 x 10-5) = 1 x 1026 Many other reactions occur during this time to create heavier elements and some free neutrons: 13C + 4He  16O + neutron 17O + 4He  20Ne + neutron 21Ne + 4He  24Mg + neutron This continues all the way up to 209Bi the heaviest stable isotope. Once the helium is all used up and the Sun’s core is fused carbon, it stops producing energy and collapses again. Now, it gets really excited and releases a much greater amount of energy. At this stage, it becomes a red supergiant, and its luminosity increases 1,000 to 10,000 times.

6. Our Sun will expand beyond the orbit of Mars, with the hot solar plasma engulfing the Earth. The orbital velocities of the inner planets will slow and they will plunge into the Sun. The frozen atmospheres of the outer planets will be vaporized and and their rocky cores will be exposed. The star Betelgeuse is a great example in the night sky. When these stars lose half of their mass to space they collapse into carbon-cored white dwarfs the size of the Earth. They are hot, but not hot enough to fuse carbon. For stars that are 25 times the mass of our Sun, things are very different. They use up their hydrogen in a few million years, helium in 500,000 years, contract further and fuse carbon for 600 years, oxygen for 6 months and silicon for a day, then….

7. At the end of the process, there is a massive star with a layered structure, iron core surrounded by concentric shells of lighter elements. The iron core does not produce any more fusion. Supernova 1994D in NGC 4526 Formation of the planets The collapse of the cloud to form the Sun transformed gravity into heat which ionized the gases in the planetary ring. The sweep of the Sun’s magnetic field speeded up the revolution of the ionized gases around the Sun while slowing the Sun down. During this period, the solar ring broke down into 10 concentric rings at specific radial distances (due to gravitational effects) from the Sun. Water, methane and ammonia liquified and wetted the solid particles, which stuck together like 1km toxic mudballs called planetesimals. At this time the Sun was ejecting large amounts of gas and strong radiation that blew all the gases that had not been trapped by planetesimals toward the outer rings. As a result, there is a catastrophic collapse that takes less than one second. The star blows up in a supernova explosion. Over the last 1,000 years, four supernova explosions have been observed in our galaxy. 20 or 30 probably occurred, but we couldn’t see them. Within a few million years, the swarm of planetesimals within each ring agglomerated into a single body, with the largest planetesimal in each ring exerting the strongest gravitational attraction. Formation of the planets was so rapid that relatively short-lived radioactive isotopes formed during the supernova explosion were trapped before they could decay. The odd plastic mash of the planets began to separate with the heavy metals sinking toward the core heating things up. The hotter the material became the faster the sinking became. They were in order of abundance H2, He, CH4, H2O, N2, NH3, H2S. The star may lose 90% of its mass in the explosion, while the core is further compressed by the implosion. Planetesimals not only formed within the solar ring, but far beyond the outer ring too. They were too far from each other to hook up and form planets. During the last 4.6 billion years many of their orbits became perturbed by nearby stars. Some of these became comets. A small comet hit Siberia in 1908 and wrecked Tunguska. The Crab Nebula- July 4, 1054 CE The Solar System Sun (mass = 1.9891 x 1030kg) 9 planets (combined mass = 2.670 x 1027 kg) 127+ satellites (combined mass = 7.20 x 1023 kg) Large number of minor planets and meteoroids (combined mass = 1.8 x 1021 kg) 1011 comets (combined mass = 1023 kg) Photos from 1927 There may be billions more in the Oort cloud beyond the solar system!

8. As these comets approach the Sun they are heated/excited and the solar wind pushes back the ionized volatile material and small grains to form a tail. This material represents the primordial composition of the solar system. Mercury has a radius of 2439 km (1524 mi), and the metallic iron-nickel core is believed to make up about 75% of this distance. Measurements of the planet's magnetic field made by Mariner 10 as it flew by the planet indicates that this core is likely to be hot and fluid. Mercury is topped with a thin crust about 100 km thick. Surface temperatures range from -184° C to 427° C (-300° F to 800° F) Venus is the brightest object in the sky after the Sun and the Moon, and sometimes looks like a bright star in the morning or evening sky. The thick atmosphere strongly reflects sunlight preventing us from seeing the surface. Venus is slightly smaller than Earth, and we think that the internal structure of Venus is similar to Earth, with a metallic core, rocky mantle, and crust. The surface is covered with craters, over 1600 major volcanoes, mountains, large highland terrains, and vast lava plains. Halley’s Comet Hale-Bopp Certain meteor showers are caused by the Earth passing through the tail of a comet. The Moon and Mercury (5.5% of the Earth’s mass) were too small to hang onto their gases and they received a beating at the hands of meteorites that we can still see today. The Earth and Venus retained most of their gases and had enough heat to maintain tectonic and volcanic activity that cleaned up any evidence of the early beating taken from meteorites. Clouds of water vapor Clouds of 80% sulfuric acid

9. Venus however has an atmospheric pressure of 92 bars (88.7 bars of CO2) or 90.4 kg/cm2. This is enough to heat the surface to 460°C from a runaway greenhouse effect. The mass of the moon is 1.23% of the Earth making is the second largest satellite with respect to its planet. The mean distance is 384,401km. The moon is the same mean distance from the Sun as the Earth, but because it does not have the thermal protection of an atmosphere its surface temperature ranges from daytime highs of 125°C to lunar night lows of-160°C. The Americans visited a number of times between 1969-72 and brought back 382kg of rocks, and left lots of equipment. The Russians also brought rocks back by robot. Although the lunar rocks are similar to Earth rocks, they contain no water, or OH groups in their crystals. It may be that the moon is a part of Mercury’s mantle that was knocked off and later captured by the Earth. The moon may also have been knocked off of the Earth by a Mars-sized object. This is known as the giant impact theory. Without the moon, the Earth’s obliquity would vary up to 85° resulting in climatic chaos. Formation of the Earth’s Atmosphere and Ocean Impact Degassing Bombardment of the young Earth’s surface by the iceball planetesimals would have released water and other volatiles in tremendous amounts A combination of the heat-generating pounding by planetesimals and the greenhouse effect related to the gases released probably kept the early Earth so warm that all water was in the form of steam. Heavy Bombardment Period Most of the water and gases that are found on Earth were probably the result of this early bombardment. This period lasted about 100 million years until 3.8 billion years ago. This shutdown of bombardment made the world safe for life to evolve. Evidence for the timing comes from the Moon, Mars, and Mercury. Earth The Earth has a mass 1.23 times that of Venus and should have produced 1.23 times more gases than Venus, in approximately the same proportion. If so, the pressure of CO2 on the young Earth’s was 97 atmospheres leading to a temperature of 90°C. Because this temperature is low enough for water to exist in the liquid state, it accumulated in low areas as the early ocean. CO2 dissolved into the ocean, reacted with silicate rocks, and precipitated as carbonate. With lots of CO2 in the Earth’s early atmosphere and high temperatures, the hydrologic cycle and weathering must have been operating at high speed. In a few hundred million years, most of the CO2 was removed from the atmosphere, leaving nitrogen as the dominant gas. Nitrogen molecules scatter blue light and the sky became blue. Composition of the Early Atmosphere Some scientists have calculated as much as 10-bars of CO2 in the early atmosphere. This would have resulted in a super greenhouse effect that yielded surface temperatures of 80-90°C even though the Sun was probably 30% less bright. Other models and geochemists have suggested that the CO2 would have quickly reacted with fine-grain particles ejected during impacts. This would have rapidly drawn down CO2 pressure and the Earth would have been quite cold. So, what’s the answer? No one really knows… The Moon The moon consists of a 200-300km iron-nickel core, a 1,400km thick mantle made of peridotite, and a crust 60km thick. Lava flows make up the large dark spots that are visible from Earth with the naked eye. Rocks no younger than 3.1 billion years old have been found on the moon. Since that time, the moon has been geologically dead except for moonquakes related to tidal readjustments. Where did the moon come from? The orbit of the moon is tilted at 18.3° to 28.6° from the equatorial plane of the Earth. If the moon formed from a ring of material orbiting the early Earth, it’s orbit would coincide with the equatorial plane of the Earth.

10. The Origin of Life Prebiotic Synthesis of Organic Compounds An RNA world requires the formation of ribose and the 4 bases (adenine, guanine, cytosine, and uracil). Ribose (C5H10O5) is composed of 5 formaldehyde (H2CO) molecules that could have been created in a CO2-rich atmosphere by reaction with sunlight. This formaldehyde is readily dissolved in rainwater, ultimately ending up in the ocean where it can spontaneously form sugars. Now to form the four bases, starting with adenine (C5H5N5). This base can be synthesized from five hydrogen cyanide (HCN) molecules. Coming up with cyanide molecules is a bit of a trick because methane is required, but may not have been present in sufficient quantities in the early atmosphere for methane photolysis. Oparin-Haldane Hypothesis The modern theory of the Origin of Life had it’s start in the 1920s as forwarded by Russian Alexander Oparin and British scientist J.B.S. Haldane. These scientists suggested that life began in a strongly reduced atmosphere as a series of chemical reactions in the ocean. These reactions were powered by sunlight and lightning. The result was a suite of organic molecules. Strongly reduced atmosphere- rich in hydrogen-containing gases, such as methane (CH4) and ammonia (NH3). Where can I get some methane dude? Turns out that methane is emitted from mid-ocean ridges as a byproduct of serpentinization which reacts seawater with ultramafic rocks. Other theories of Life’s Origin Many researchers think that the HCN and H2CO molecules would be too few and far between to hook up. Also, they would be destroyed by incoming solar radiation and heat. What other possibilities are being entertained? Interplanetary Dust Particles (IPDs)- organic molecules including amino acids are recovered from IPDs and certain meteorites and have been found in interstellar dust clouds. If these organic molecules survived the collapse of the pre-solar nebula, they could have arrived on the many bombs that hit the Earth between 4.5 and 3.8 Ga. Miller-Urey experiment In 1953, University of Chicago scientists filled a flask with gases that they thought represented the early atmosphere (H2, CH4, NH3, and H2O), and zapped it with electrical discharges. A brown slime quickly appeared on the side of the flask that contained complex organic molecules that included amino acids that serve as the basis for proteins. Hydrothermal vents present a third possibility for the origin of life. Water passes through a kilometer of seafloor, gets heated and rises through a ridge vent. While passing through the crust and sediment, the water picks up reduced H2, H2S, and ferrous iron (Fe2+) which is soluble in the hot anoxic water. Proteins- composed of one or more chains of amino acids. They may be transport molecules, enzymes, or hormones. This experiment rocked the world, but is now being reconsidered to a degree because NH3 and CH4 are split by solar radiation and would have been in lower concentrations than originally suggested. These questions have led to a new way of looking at the origin of life. RNA world Thomas Cech and Sidney Altman won the 1989 Nobel prize in chemistry for their discovery that certain RNA molecules could self-cleave, and thus replicate themselves. DNA on the other hand requires an enzyme made of proteins. This implies that our current DNA world was proceeded by an RNA world. Black smoker- when hot (350°C) plume water hits cold seawater, it generates a dark plume of predominately iron sulfide FeS, as well as many other compounds in lesser amounts. These vents are rich in the reduced materials needed and have plenty liquid-solid interfaces (like pyrite) to help organize the organics. Because the temperatures are too high to likely form and preserve organics for any length of time, the next step probably took place off-axis.

11. This may serve as proof of life originating in hydrothermal waters, or it may merely represent the greater molecular stability of the guanine-cytosine (G-C) bond in DNA. This would lead to more of these bonds in high-temperature organisms which makes them appear more primitive. Here is where the primordial soup thickens. When did life arise? Until the 1840s or so, it was believed that life evolved at the beginning of the Cambrian Period when animals with hard parts first appeared. In the 1940s microfossils were found in more ancient rocks. Sometimes single-celled organisms were observed in siliceous rocks. Apex Chert fossils(?) in the Warrawoona Formation are 3.5 billion years old…if they are fossils and not just carbon chains from hydrothermal vents. Stromatolites are common in slightly younger rocks around the World. More on this from Dr. H. Low carbon isotope values in the 3.85 billion year old Isua rocks of West Greenland may indicate life…or not because some of these rocks are now known to be igneous. More on this from Dr. H. Life could have evolved in surface waters during the bombardment period in Earth history and spread to all environments. Impacts would sterilize the land and surface waters with only the very deep water organisms surviving to eventually colonize all the Earth’s environments. The Universal Tree of Life Sequencing of RNA and DNA has permitted development of a history of increasingly complex organisms. PCR (polymerase chain reaction)- allows for development of a tree of life with three main branches. Bacteria and Archaea are single-celled organisms known to us as bacteria. Eukarya can be single-celled organisms as well as all higher plants and animals. Hyperthermophillic bacteria (live above 80°C) are all found near the stump of the tree of life. So what?