The Early Earth - Essay Example

Early Earth DECEMBER 2006 Feature Main Page Photo Gallery See more of Frans Lanting's images in his multimedia project "Life: A Journey Through Time" at www.LifeThroughTime.com. By Tim Appenzeller Photographs by Frans Lanting Modern landscapes offer glimpses of the way our planet may have looked billions of years ago. The early Earth was a vision of hell, all scalding rock and choking fumes. Since then, its surface has cooled, continents have drifted, mountains have risen and eroded, and life has emerged, benign and green. Nearly all traces of the planet as it was have been wiped away. But from clues in the oldest rocks, deepest magmas, and even the cratered face of the moon, scientists have traced the planet's beginnings. As those early days have come into focus, so have the rare scenes, found today in some of Earth's harshest places, that recall its ancient self. Its birth pangs began some 4.6 billion years ago as rock and ice particles swirling around the young sun collided and merged, snowballing to produce ever larger planetary building blocks. In violent pileups, they smashed together to create planets, including the infant Earth. In the turmoil, another body, as big as Mars, struck our planet with the energy of trillions of atomic bombs, enough to melt it all the way through. Most of the impactor was swallowed up in the bottomless magma ocean it created. But the collision also flung a small world's worth of vaporized rock into orbit. Debris quickly gathered itself into a ball, and since then Earth history has unfolded beneath the blank stare of the moon. After the moon's fiery birth, the Earth's surface cooled. Even so, our planet remained an alien world for the next 700 million years; scientists call this time the Hadean, after the Greek underworld. Rafts of solid rock drifted in the magma like dark ice floes. Gases hissed from the cooling rock-carbon dioxide, nitrogen, water vapor, and others-enveloping the planet in a scalding atmosphere devoid of oxygen. As the temperature dropped further, the steam condensed into rain that fell in primordial monsoons and filled the ocean basins. These first oceans may have been short-lived. Space rubble left over from the birth of the planets-chunks of rock tens to hundreds of miles across-bombarded Earth throughout the Hadean. The greatest impacts might have boiled the oceans away, forcing the process of cooling and condensation to begin again. By 3.8 billion years ago the impacts relented. Liquid water could persist. About that time, perhaps in the oceans, lifeless chemical reactions crossed a threshold, producing molecules complex enough to reproduce themselves and evolve toward greater complexity. Life was on a road that led, as early as 3.5 billion years ago, to single-celled, blue-green cyanobacteria that flourished in the sunlit parts of the oceans. By the trillions, these microscopic organisms transformed the planet. They captured the energy of the sun to make food, releasing oxygen as a waste product. Little by little they turned the atmosphere into breathable air, opening the way to the diversity of life that followed. Those days are long gone, but the processes that turned our planet from a hell to a habitable world are still on view today, as the images on these pages show. Primordial heat left over from the planet's formation still bursts out in volcanic eruptions, spilling lava that exudes gases like the young, cooling Earth. In the planet's harshest environments today, cyanobacteria reign as they have for billions of years. And each time a plant gains a toehold on newly cooled lava, the victory of life over lifeless rock-won so long ago on the young Earth-is affirmed again. Subscribe to National Geographic magazine. The Earth began as a bleak surrounding where hot and fiery rocks and poisonous fumes existed. This is what the article from National Geographic Magazine, titled Earth in the Beginning written by Tom Appenzeller, illustrates. The article describes the early Earth as hell-like but cooled eventually as continents started to shift away from each other. Consequently, the earth's terrains have been transformed as mountains rose and fell. Life also arose and the traces of the early earth's features gradually disappeared. But scientists contend that there are clues to be gleaned from the earth's early beginnings - clues that could also be found even in the moon's rough craters. The earth's beginnings, as I have learned from this article, began some 4.6 billion years ago 'as rock and ice particles' revolving around the sun crashing and merging spawned into a bigger which generated huge terrestrial building blocks. These matters collided to form planets, including the Earth. Amidst this chaos, another matter the size of Mars, hit our planet with the force of 'trillions of atomic bombs', adequate to liquefy it in the end. The debris rapidly assembled itself into a sphere, and since then the history of the earth began. Moreover, I learned from this article that the earth began to cool with the formation of the moon as a natural satellite but the earth remained in an extreme condition for about 700 million years. Astronomers refer to this time as the Hadean period which in Greek means, hell or the underworld. Our planet at that time was replete with hot lava flowing out from different volcanic- like sources and gases oozed out of the cooling rocks. The atmosphere and the temperature were exceedingly blistering, making it impossible for life to exist. The earth's temperature cooled down further and monsoon rains began to fill basins and empty spaces of the earth's landscape. These were the earth's first oceans and they did not last long. Huge matters from space, remaining after the planets were formed, constantly barraged the surface of the earth throughout this period known as the Hadean. These huge pieces of rocks measures tens to hundreds of miles across in size. The results of these impacts might have dried out the first oceans on the surface of the earth. When these assaults from the outer space ceased 3.8 billion years ago, liquid began to appear on the surface. Life then, started emerging in the oceans as products of chemical reactions. These complex molecules reproduced and evolved to more intricate and complex. About 3.5 billion years ago, the first life appeared which scientists labeled as the 'single-celled, blue-green cyanobacteria' which grew in areas lighted by the sun's rays. The organisms reproduced in trillions transforming the planet which utilized the sun's energy to create food thereby emitting oxygen as a waste product. These organisms transformed the atmosphere and provided it with breathable air making it possible for other organisms to thrive. The traces of the extremely scorching environment disappeared and what we see now across the earth are the remains of the Hadean past. The volcanoes for instance are the examples of the remains of the earth's early beginnings intermittently exploding and spitting out lava and gases similar to the situation that could be observed in the early days of our planet. Still, in our planets harshest conditions, cyanobacteria have reigned supreme for billions of years. This article paints an amazing portrait of our planet's past, how our atmosphere began and how life evolved afterwards. It also illustrates the organisms' hardiness against extreme conditions. The question is, if those organisms exhibited impervious behavior amidst a hell-like environment, why were other single celled organisms found on the surface of Mars relented What are the factors which could have supported life in other planets in our solar system uniquely present on Earth during the formation of life These questions are not easy to answer as there were billions of factors and reasons which could have contributed to the formation of life on earth. But if chemicals turn complex as if they have a life of their own, will the same molecules of chemicals present in other planets inside and outside our solar system The answer of course is yes, since we came from the same 'matter' which disintegrated after the explosion. One of the most difficult question I would like pose is, if billions of factors multiplied by billions of factors contributing to the emergence of life on earth, using the law of probability, and also billions of similar factors occurred in other areas of the universe in billions and billions of matters, planets and stars - borrowing the words of the great astronomer, Carl Sagan, would there be billions of planets which could harbor life My next question then is: What is the result of higher number of probabilities Does the probability decrease or it increases Most mathematicians would answer that the higher number of factors multiplied by a high number of factors results to many factors having similar results - as the higher the probability, the higher the result. If we apply the same theory on the emergence of life on earth, let's say the emergence of intelligent life, using modern humans as examples, will there similar kinds of 'modern humans' in the universe Or my assumption is that, if factors multiplied by billions and other factors multiplied by billions, won't the probability decrease Will the chances decrease My answer to that is yes. Though it is very tough to illustrate this assumption, I'll try to support these contentions. There were billions of events which occurred during the formation of the earth. Let's say, only one in every billion is a factor which will result to its proper harboring of life. Let's say again that another billion of events happened but similarly, only one in the events contributed again to the development of complex chemicals and molecules, will these billions and billions have parallel events in the universe where billions and billions of solar systems exist Let's say again that after the chemical produced after billions of events, and after billions of variations in temperature, only one from that variation is a contributor in which life of single celled organisms develop from, will it still have some parallel event in the outer space or in the planet outside our own This is not only mind-boggling but it would be understood better if a mathematical formula for probability in extremely high number be developed. If we apply this analogy in the tossing of the coins, will the concept be easily grasped Let's say there are billions of coins and each has different kind of face and tail which means we also have a billion faces and a billion tails, then we toss them a billion times and another group of a billion coins with a billion faces and tails tossed a billion times. How much probability, let's say in percentage results to Or can we actually apply probability in the emergence of life If life on earth arose by chance, then we live 'at the toss of a coin', where life is unpredictable and life's meaning appear by chance - and if our universe is governed by chance, then similar occurrences of 'chances' may exist. Can we still say we are alone in a universe of chance Read More