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The most famous theory of the universe's existence, the big bang, which is based around a cosmic cataclysm in all human history, best explains the universe's origin. The discovery that all other galaxies travel away from our own at a much faster rate, in all directions, as if launched by an archaic atomic force gave rise to the big bang hypothesis. According to adherents of the big bang theory, a monolithic explosion between 10 billion and 20 billion years ago caused all matter, space, time, and energy in the universe to form from some antediluvian and unknown energy type. All the aspects observed on earth obviously emerged after the formation of the universe. The paper sets to critique and challenge most of the generally held beliefs about the various concepts on the cosmos, with substantial support from the things I have learned in high school, college, documentaries about the universe, daily activities, as well as movies. There are various concepts presented in the different course topics that I will attempt to challenge, and as well give credit where I tend to agree with the content of the topics.
The origin of the Universe
According to the big bang theory, the instantaneous moment (a trillion-trillionth of a second) after the big bang, there was an expansion of the universe in an incomprehensible speed from its small size origin to astronomical scope. As explained by Seeds and Backman (1999), the expansion has continued over the billion of years, even though it has been more slowly.
Despite the popularity of the theory, I tend to question the origin of the big bang itself. It is expected that since the earth was desolate and formless as has been ascertained by scientists, then nothing could have happened out of nowhere, for instance, the big bang that consequently caused the expansion. As I have learned in my high school and college physics, it is impossible to create or destroy energy or matter, as per the third law of thermodynamics. Therefore, I tend to challenge the big bang theory in that it suggests that the universe started out of nothing. In addition to the origin of the universe as explained by the big bang, I tend to wonder how scientists remain sure exactly how the universe evolved after the big bang. Besides, I still question the fact held by many i.e., as time passed and the available matter cooled, there was the formation of more varying kinds of matter that eventually cooled to form the stars and galaxies that are observed in the current universe.
The Birth and Death of Stars
It is an undisputable fact that the Milky Way Galaxy is made up of several hundred billion stars that are of all sizes, ages, as well as masses. The sun for instance, which is an example of a typical star, radiates small amounts of X-rays over and over again, and larger fragments of X-ray whenever there is a solar flare (Seeds & Backman, 1999).
According to astronomers, stars begin to form as a dense or giant cloud of gas and dust and later move through their normal life as gas balls that are heated by thermonuclear reactions in their centers (cores). Hydrogen atoms drop with increasing energy and speed toward the cloud center under the speed or force of the gravity of the stars involved. The rise in energy causes a considerable heating of the gas, and the process continues for many years (millions of years) leading to a spike in temperature to about 20 million degrees Fahrenheit. Such high temperatures cause the hydrogen within the star to combust in continuous nuclear reactions. As the reactions start, the stars are born. On the other side, the death of the star is reached when it exhausts its hydrogen supply as this makes its life come to an end. Such continued exhaustion leads to a collapse of the star under the force of its own weight.
The theory of the birth and death of a star is considerably factual in that spells out that the heavenly bodies arise from somewhere. The heating of the ball of gas is in one way or another proving that thermonuclear reactions are capable of bringing in distinguishable changes in stars. Besides, the fact that the death of a star is dependent on its mass is convincing in that the mass determines whether a star will evolve as a white dwarf, a black hole or even a neutron (Seeds & Backman, 1999).
Properties of the Earth, Moon, Mars, and Venus
Earth is the third planet from the sun and is endowed with numerous properties. According to earth bound and spacecraft observations, Earth is positioned within the "habitable zone" if the solar system, and it is at 92,957,130 miles, hence its uniqueness within the solar system. Earth is 7,926 miles in diameter around the equator, and its circumference is 24,902 miles. Among the surface properties of the Earth is that it is covered with 71 percent water which is essentially for life. The liquid is also responsible for the increased erosion observed on the land masses of the Earth (Seeds & Backman, 1999). Planet Earth is believed to be approximately 4.5 to 4.6 billion years old, even though the oldest rocks are known to be four billion years old.
There are five layers of the Earth namely crust, upper mantle, the region of transition, lower mantle and lastly the core (Seeds & Backman, 1999). The crust extends down to 24 miles with its major composition being quartz. Regarding the moon, there are hundreds of them in the solar system, and some asteroids have been ascertained to have small companion moons. Earth's moon is thought to have emerged when a large body (Mar's size) collided with Earth releasing numerous materials from it (Earth) into orbit. The Moon is the second brightest after the Sun which is found in the sky. I have gained enlightenment from astronomy classes in college that the Moon orbits around the Earth once in every month, and as this happens, the angle between the Earth, the Moon, and the Sun goes through some alterations. Another property of the Moon is that the gravitational forces between it and the Earth cause various interesting effects i.e. tides.
I have learned that the Moon has no atmosphere even though there has been evidence suggesting the possibility of water ice in some of the deep craters adjacent to the south pole of the Moon, and which are permanently shaded. Also, the Moon has no global magnetic field, but it is worth noting that some surface rocks found in it show remanent magnetism. With such evidence, there is an indication that at some point in the Moon’s early history, there probably was a global magnetic field. According to the information I have gained in the course of my astronomy classes, from high school as well as in college, I generally agree with the above information. The course has taught me various aspects of the properties of the Moon and Earth, which all appear to be factual in my understanding.
Mars, on the other hand, has various significant properties i.e. it is about half the Earth's diameter, it is less dense than Earth (has 15% of the volume of Earth and 11 % of the Mass) (Seeds & Backman, 1999). The surface of Mars has a red-orange appearance which is due to accumulation of hematite/iron III oxide (rust). The planet is also observed to look like butterscotch. Other surface colors of the planet are golden, greenish, tan, and brown, which are all determined by the available minerals.
Venus on the other side has similar size, density, mass, composition as well as distance from the Sun with Earth, and it is worth noting that the similarities end at that point (Seeds & Backman, 1999). Venus is covered by a thick atmosphere that is quickly spinning, and as a result, there is the creation of a scorched world whose temperatures are extremely hot (can melt lead), and also have a surface pressure that is 90 times that of Earth (Seeds & Backman, 1999). The atmosphere of Venus is mainly made up of carbon dioxide as well as some clouds or drops of sulfuric acid, making the planet toxic. Therefore, the planet is uninhabitable by living things. Since the spacecraft used to observe the above bodies of the solar system have high accuracy, I tend to concur with the above knowledge. I have learned much of the information in high school and also in college. Besides, I watched various YouTube documentaries such as “The Mysteries of Venus” and “Alien Worlds Beyond our Solar System” where the properties of the various bodies in the universe are explored.
The Origin and History of Life on the Earth
Astronomists believe that the Earth is more than 4.5 billion years old, and the zircon crystals are its ancient materials (4.3 billion-year-old). The earliest times of the planet saw geological violence, and the Earth went through repeated bombardment from meteorites. After the formation of the continents, they have repeatedly collided and torn apart, and the situation has changed over time. The history of life on Earth started about 3.8 billion years ago, and it began with single-celled prokaryotic cells i.e. bacteria. Over a billion years later, there was the evolution of multicellular life. The kind of life forms that humans are familiar with i.e. arthropods only began to evolve in the last 570 million years. Other life forms later evolved such as fish (530 million years ago (Ma)), land plants (475Ma), and forests 385Ma. Mammals evolved 200 Ma, and the Homo sapiens (our own species) only evolved 200,000 years ago. Therefore, from the course materials in college, I have learned that human beings have been present on the Earth for just 0.004% of the history of Earth.
The next aspect to be challenged is the impact of astronomical and geological changes on biological evolution. There has been considerable evidence of recent impacts of astronomical and geological alterations on life in Earth. For instance, the collision of interplanetary materials or debris with planet Earth is a practical idea. Such instances are broadcasted daily in the media. Besides, historic cases of collision have been described well in books (astronomy and geology). For instance, while researching on the topic of impacts of debris collision, I came across the historic collision that took place in Siberia (near River Tunguska) on June 30, 1908. It is explained that a remarkable explosion happened in the atmosphere, and it flattened over a thousand square kilometers of forest. As a result, many reindeer and other animals died, and a man who was at a trading post (about 80 kilometers away from the blast) was violently thrown and knocked unconscious.
In addition, such astronomical changes are likely to lead to mass extinction of evolving species on Earth. For instance, I have read in astronomy that larger impacts have the potential to impair the ecological balance of the entire planet Earth and in so doing, impact the course of evolution.
Life and Intelligence in the Cosmos
In the modern world, the question of whether there could be intelligent life beyond Earth has dominated the field of astrology. According to astrobiologists, there are chances that microbial life will develop intelligence like the one with human beings. The Darwinian evolution enables biologists to understand the process of such microbial life evolving intelligence. I have read in astrology books that most scientists (astrologists) hold the belief that origin of life is actually not that hard, or else it would have been difficult for it to emerge rapidly when planet Earth became hospitable. Nonetheless, such a belief faces criticism in that unless life on Earth had begun so quickly, human beings would not have emerged or evolved before the sun becoming too hot beyond bearable levels. Astronomers also believe that there is a possibility of billions of earthlike planets in the galaxy we live in alone. In daily discussions, I have also heard people argue that there cannot lack habitable real estate out there in the cosmos.
Philosophical implications in the synthesis of astronomy, earth sciences, and the history of life
It is evident that Earth science has received considerably little attention from science philosophers. For instance, philosophers of science dwell much on such concepts as dinosaur extinction and plate tectonics but disregard most of the earth science. According to most philosophers, astronomy and earth science cannot be considered as autonomous science as both can be reduced to more basic sciences i.e. chemistry and physics. In one way or another, I tend to agree with philosophers since most of the explanations such as the origin of the universe as well as the birth and death of stars are concepts that can be described or elaborated in chemical or physical terms. In that light, the earth sciences and other significant astronomical aspects can be considered as reducible to the more fundamental sciences. However, I would also bring forth the thought that astronomy, earth sciences, and the origin and history of life should be accorded more philosophical attention in the sense that the geosciences are endowed with typical features that differentiate it from natural sciences.
In conclusion, the paper has assessed various concepts of the astronomy course regarding personal experience and knowledge about the subject. I have provided deep insights on the specific topics as found in the course. Most of the content of the topics are factual but can as well be challenged, hence my venture to criticize it. Nonetheless, I have attempted to explore varying perspectives of the different topics and provided the background or foundation of my knowledge about the topics i.e. from high school, documentaries, college and also daily activities.
Seeds, M. A., & Backman, D. E. (1999). Astronomy: the solar system and beyond. Belmont, CA: Brooks/Cole, Cengage Learning.
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