Earth Science: Formation of the Universe PDF

EARTH SCIENCE Ms. Joana Marie C. Avis 2022-2023 1  Earth Science DYCIan Learning Account No. 1 FORMATION OF THE...

EARTH SCIENCE Ms. Joana Marie C. Avis 2022-2023 1  Earth Science DYCIan Learning Account No. 1 FORMATION OF THE UNIVERSE “Who are we? Just a speck of dust within the galaxy” An iconic line from a song coming from a popular band that presents the vastness of the cosmos comparing to everyone’s existence. The mystery brought by the unfathomable universe drives human’s fascination to uncover the wonders and seek answers hiding deep on the universe. At the end of this learning account, you are expected to: 1. Describe the structure and composition of the Universe; 2. State the different hypothesis that preceded the Big Bang Theory of the Origin of the Universe; 3. Explain the Big Bang Theory and evidences supporting the theory. On a clear weather, you see countless stars scattered in the night sky. These small dots lighting the sky is one of the many occurrences that made humankind curious about the hidden secrets of the universe waiting to be unveiled. As the early civilization struggled to understand how everything came into being, the awe and continuous study to this branch of knowledge up to these days is flourishing. The universe as we currently know it comprises all space and time, and all matter and energy in it. Starting from the ideas of the philosophers as they attempt to comprehend the movement of heavens and various theories that arose from the scientists in the formation of the universe, knowledge about the cosmos is continuously evolving every time to give us better understanding of how the universe was and how the universe will be. The question “How did the universe came into being?” represents the attempts of mankind from the beginning as we try to make meaning of the world we are living in. Ideas from the people of the ancient times influenced the belief of humanity long before people became aware of Science. Various beliefs from different cultures let the non-scientific way of thinking emerge from the origin of the universe. The understanding these civilizations had of the universe is very different to what science teaches us today. Non-scientific theories on the Origin of the universe: Here are different cosmogenic accounts that arose from different cultures before Science has been able to give its version of facts: 2 Earth Science 1. Egypt The evidence found in the writings and works shows that the early civilization in Egypt is already making sense of the world around them. Egyptians on the ancient times view the creation of everything in a spontaneous process based on mythology. Atum, their sun-creator god was asleep for a long time in a primordial sea called the Nun. The universe emerged from a vast cosmic ocean of nothingness when the sun- creator god summoned an island to come out of the cosmic sea. At the top of this mound he proceed to ordained different gods and goddesses to govern every Figure 1.1 Egyptian Creation Myth aspect of nature (Mark, 2013) Photo credit: The Picture Art Collection/ Alamy Stock Photo, 2003 2. Central Africa The Kuba people of Africa believed in their creator god Mbombo (or Bumba) who alone existed when there was only darkness and water. The creation story tells that Mbombo is ill for eons because of his loneliness. After experiencing an intense pain on his stomach, Mbombo vomited the sun which causes night and day (Parkes, 2018) After throwing up for the second time, the moon and stars were created. The vomit for the third time created animals which all the other creature came from. Figure 1.2 Mbombo, the Kuba people’s creation God vomiting the universe Photo credit: Ancient Origins, 2016 3. India Hinduism being the world’s oldest religion based their mythological creation story on Purusha, the primal man. He has thousands of heads, eyes, and feet. Purusha’s body was offered at a primordial sacrifice of the gods (Harper, 2011) Each part of his body created the heavens, wherein the head became the sky, his feet became the earth, his eyes became the sun, and his mind as the moon. Figure 1.3 Purusha the primal man from whose body the universe was created Photo credit: danielharper.org, 2011 3  Earth Science 4. Monotheism “Monotheism is the belief in the existence of one god, or in the oneness of God” --Theodorus P. van Baaren Contrary to polytheism or the belief in the existence of gods or deities, monotheism represents the Judeo- Islam-Christian belief claims that one supreme being created the universe, including man and other living Figure 1.4 Religious symbol of three organism. God is considered as an omnipotent being, Abrahamic monotheistic religion the ruler of the universe, and the creator of all. Photo credit: dreamstime, 2020 After knowing various thoughts about the origin of the universe, can you consider these religious beliefs or mythological accounts possess scientific validity? Proving something of scientific validity, you must follow scientific method. The non-scientific thoughts mentioned above cannot be clearly subjected to tests and cannot present evidences that of scientific basis. In the next part, you will dive deeper on the prevailing scientific theories on the origin of the universe and its evidences, together with the structure and composition of the cosmos. Scientific theories on the Origin of the Universe: 1. Steady state theory Fred Hoyle, the major proponent of the Steady state theory, together with Hermann Bondi and Thomas Gold states that the existence of the universe is based on a perfect cosmological principle which supports the unchanging yet dynamic universe. Unchanging because the universe had no beginning, which signifies the universe is infinitely old and have no Figure 1.6 Tommy Gold (left) with concept of time, and dynamic because it is always Hermann Bondi (center) and Fred expanding. This theory contradicts the Big bang theory Hoyle (right), circa 1960 which is the widely accepted scientific theory on the Photo credit: Ideas of Cosmology by Center for History of Physics, a Division of the origin of the universe. American Institute of Physics Hoyle stated that in a steady state universe, matter is continuously created over time, thereby maintaining the density of the universe. The universe does not evolve and is constant Figure 1.7 Steady State Theory Model which means it looks the same at every place Photo credit: NASA Cosmic Times, 2017 and every time. This means that there is a 4 Earth Science continuous creation of stars and galaxy to replace the stars that used up its fuel while the older ones were being pushed away. This theory is rejected with the discovery of cosmic microwave background radiation which will be introduced to you on the next discussions 2. Big Bang Theory The Big Bang Theory is the prevailing cosmological theory on the origin of the universe. It postulates that 13. 7 billion years ago, the universe experienced a sudden inflation from a singularity to its present size and much cooler state (Howell, 2017). Georges Lemaitre, was the first proponent to attempt an explanation of Big Bang based on the notion of the “primeval atom”. The primeval atom is termed today as the singularity which was mentioned earlier. The singularity is the initial condition of the universe wherein it is infinitely hot and infinitely dense state that undergone expansion up until this time. Figure 1.8 Georges Lemaitre a Belgian priest and cosmologist who is considered as the Father of Big bang Photo credit: Encyclopedia Britannica, 2010 Years later, George Gamow formulated the Big bang theory known today, which is backed-up with evidences. It holds the premise that the universe came into being from a gigantic inflation of the primeval atom or the singularity. Gamow together with his colleagues, explained the series of thermonuclear reactions that happened that distributed chemical elements throughout the universe. Figure 1.9 George Gamow, an advocate of Big Bang which he revised and extended Photo credit: Encyclopedia Britannica, 2012 Contradicting Hoyle’s steady state theory stating the density of the universe remains more or less constant as the universe expands, the density of matter in the Big bang model decreases as the universe expands because the volume of space increases. On the next part we will not discuss one by one the different epochs or era in Big bang, but you just focus on major events and the Figure 1.10 Big Bang or Evolutionary Theory Model Photo credit: NASA Cosmic Times, 2017 relationship between time elapsed and temperature of the universe that time. 5  Earth Science Figure 1.11 The graph presents the relationship between the time variation (x-axis) and the temperature (y-axis) in Kelvin of the major events that happened in the Big Bang. Photo credit: lumen learning astronomy, 2016 If questions like “how did the scientists knew about these things if in the first place no one exists yet to gather that data?”, the answer lies on the theoretical calculations made by these astronomers. As you can see on the data above, the sudden inflation of the singularity happened in less than a second which is 10-43 second wherein the temperature at this time is also at the extremes. The following events that happened right after the Big Bang happened on a mere fraction of less than one second. Imagine how rapid the turn of events took place and in that sudden happenings, everything exists now! The temperature is too hot for matter to form and radiation mostly dominates the early universe. Observe that as time elapse lengthens, the temperature also drops to form the earliest atoms that undergone different thermonuclear reactions to form the stars then the galaxies you are existing this time. As mentioned earlier, no one exists yet that time to record the happenings during Big bang yet how did the scientists attempt to explain the formation of the universe using that premise? Just think of the investigators or those people in SOCO or FBI or those forensic scientists in your favorite show, how can they point out who is the culprit or what happened during the crime if in the first place they were not in the actual crime scene? And yes the answer lies on the evidences they gather. Like those people, cosmologists also find evidences to prove what they are trying to explain in the formation of the universe. After discussing the Big bang concept, let’s now proceed to the evidences given by the scientists to prove their claim about this theory: Evidences supporting Big Bang: Universal redshift This major evidence of the Big bang theory by Edwin Hubble infers that the galaxies are moving away from one other which supports the Figure 1.12 Edwin Hubble was the first expansion of the universe. to describe the redshift phenomenon Photo credit: NASA 6 Earth Science To further understand this, you need to recap first the concept of Doppler effect. The Doppler effect is a phenomenon associated with waves, sound wave and light waves included (Harris, 2015) Considering Doppler effect in sound which you can observe in your daily life, is the approaching sound of an ambulance. Obviously, as the ambulance moves toward you as the observer, you will hear a high-pitched sound coming from it. The reason for this is the increase in frequency and energy of the sound wave as the wavelength shortens according to NASA. On the other hand, as the ambulance is receding or moving away from you, the sound become low-pitched because of the drop of the frequency and energy of the soundwave as the wavelength lengthen as shown by figure 1.13. Figure 1.13 Illustration of Doppler effect in approaching and receding ambulance Photo credit: thermaxx jacket, 2014 Now, you know as the source of wave moves towards you, the wavelength decreases because it has high energy and frequency, opposite if the source of wave is moving away from you. Light waves are perceived as color. In your Science 10, you have discussed that visible light is the portion of the electromagnetic spectrum which the human eye can view. On the visible light spectrum, violet has the shortest wavelength and red has the longest wavelength. An observation by Edwin Hubble that the spectral lines of starlight coming from galaxies he studied was shifted to the red end of the spectrum (Harris, 2015) Figure 1.14 The shifting of spectral lines towards the red So what does it mean when studying distant galaxies? If or long wavelength end of you observed a galaxy here on Earth that shifts to the red the spectrum (right on this part of the spectrum, it means the source moves away diagram) is called the redshift. from you and its wavelength gets longer (Fraknoi et al., Photo credit: astronomy stack exchange, 2019 2016) It gives you an inference that galaxies are moving away from one another, thus the universe is expanding. 7  Earth Science Cosmic microwave background radiation The first “afterglow” of the hot, early universe is termed as the cosmic microwave background radiation (Howell, 2017) It is a vital evidence of Big bang that supports the expansion of the universe. Figure 1.16 A 2013 map of the background radiation left over from the Big Bang, taken by the ESA's Planck spacecraft, captured the oldest light in the universe. Photo credit: © ESA and the Planck Collaboration The discovery of cosmic microwave background radiation is an unexpected feat for radio astronomers Robert Wilson and Arno Penzias as they are studying supernova remnants. According to NASA, the two were being disturbed by an excess noise like a faint radio static and picking temperature higher than the usual as they were building a radio receiver. This radiation as they observed is coming from all directions at once, unlike most radiation has a specific direction where it is strongest. Figure 1.17 Robert Wilson (left) and The cosmic microwave background radiation is the oldest Arno Penzias (right). These two light you can see--the farthest back both in time and scientists are standing in front of space that you can look. According to Howell (2017), the horn-shaped antenna with examination of CMB led astronomers to find out the which they discovered the cosmic composition of the universe, other than the galaxies and background radiation. The photo stars, which brought them in studying dark matter and was taken in 1978, just after they received the Nobel Prize in Physics. dark energy which will be discussed here later. Up until this time, cosmic microwave background radiation has Photo credit: lumen learning cooled down since the Big bang and can be detected astronomy throughout the universe. Abundance of light elements (Hydrogen, Helium, and Lithium) It is not until 3 minutes after Big bang when subatomic particles proton and neutron joined together to form the nuclei of the first elements in the universe which is Hydrogen. Series of thermonuclear reactions take place for the first Hydrogen nuclei to combine and form the nuclei of the next light element which is Helium. You must take note that three minutes after the Big Bang, only the nuclei of the first atoms were formed and those times, the universe 8 Earth Science achieved its ideal temperature and condition for the two positively charged particle to fuse and not repel to each other (Padua et al., 2016) The formation of these atomic nuclei is termed as nucleosynthesis. When the temperature of the universe cooled down to 3 000°C after 300 000 years, protons began combining with electrons to form Hydrogen atoms through nuclear fusion. These Hydrogen atoms combined with neutron to form the atom with has slightly more mass which is Helium. From this concept, you can conclude that until this time, nuclear fusion of Hydrogen into Helium is the source of power of the vast majority of stars. With the abundance of these Figure 1.18 Distribution of the two elements, stars and galaxies is continuously elements in the universe created as the universe expands. Photo credit: weebly, After knowing the origin of the cosmos based on scientific and non-scientific thoughts, do you ever wonder what is the universe made of? Are there more to galaxies and stars that make up the universe? On the next part, we will now continue to unveil the mysteries underlying the structure and composition of the cosmos. The structure and composition of the cosmos Figure 1.19 reveals the percentage distribution of the composition of the universe Photo credit: open stax astronomy, 2016 9  Earth Science Upon analyzing the graph on the previous page, what conclusion can you draw from it? Does it bother your idea that only 5% of what makes up the entire universe composes the matter known here on Earth and less than 1 % hold the stars? Another shocking information is that 95% of what really composes the universe is unknown to most people. What are those two things that makes up the entire cosmos? 1. Baryonic matter Baryonic matter makes up the smallest fraction (5%) of the structure of the universe. These are normal or ordinary matter that consists of protons, electrons, and neutrons that make up atoms, planets, stars, galaxies, nebulae, and other bodies known here on Earth (The European Space Agency, 2003) Figure 1.20 Milky way galaxy Photo credit: NASA 2. Dark matter According to Fraknoi et al., 2016, dark matter which made up 27% of the structure of the universe exerts gravity and surpasses all the known stars and galaxies in the universe but does not emit or absorb light. Gravity alone cannot hold the galaxies together for a long time so theories led scientists to propose that this mysterious substance exists even they still have not yet observed it directly and studied what it is made of. Evidences of Big Bang especially the cosmic Figure 1.21 This Hubble Space microwave background radiation left have made Telescope composite image shows a the scientists to confirm that this substance led to the ghostly "ring" of dark matter in the formation of large galaxies seen in the universe galaxy cluster Cl 0024+17. today. As they observed, many galaxies have large Photo credit: © NASA, ESA, M.J. Jee and H. halos of dark matter in them that affect their Ford (Johns Hopkins University)) interactions with other galaxies (Fraknoi, 2016) 3. Dark energy If the existence of dark matter shocked you, there is another mysterious substance that holds 68% of the universe, the dark energy. Dark energy can explain the accelerating expansion of the universe (Fraknoi, 2016). Compared to dark matter, scientists cannot 10 Earth Science Figure 1.22 reveals changes in the rate of expansion since the beginning of the universe. Astronomers theorize that the faster expansion rate is due to a mysterious, dark force that is pulling galaxies apart which supports the universal redshift. Photo credit: NASA/STSci/Ann Feild clearly explain dark energy for they do not have enough data for it and some hypothesis claim that its existence will defy the other laws of Physics. One idea arose that dark energy seems to be the fifth force of nature, which fills the universe like a fluid according to an article on National Geographic. Even if dark energy supports the model of the expanding universe, scientists are yet to discover the reason for the existence of this mysterious force. When you start knowing something, you figure out that there is more to know about it. As you explore the hidden wonders of the universe, you have come up with the realization that more is unknown than known. On the last part of this discussion about the formation of the universe, we will focus our discussion on the stars, the fundamental building block of galaxies and the thing that is most familiar to you when we talk about the universe. Star formation You could not help but admire the beauty of patches of light as you look at a clear night sky. Since the ancient times, humankind had been using stars for many reasons to help their everyday living. People use the stars, in the form of constellations, as an indication of the start of farming season and for travelers, it serves as a tool for navigation. Today, astronomers are continuously observing and studying these most recognizable celestial objects to calculate the age of the universe Figure 1.23 shows the Tarantula and record its accelerating expansion. We will tackle Nebula how do stars form and the fate of the stars. Photo credit: NASA Spitzer Space Telescope 11  Earth Science Figure 1.24 shows major events in star formation Photo credit: HowStuffWorks, 2010 According to NASA, stars are luminous objects born within clouds of gas and dust scattered through galaxies. This Hydrogen-based dust clouds are termed as nebula (Zuckerman, 2019). The materials inside the cloud are very unstable. The disturbance of this unstable material within the nebula, compression caused by gravitational force eventually cause the denser portion of the clouds to collapse under their own weight. After the gravitational collapse, the interior of this material started rotating and heats up, forming the protostar. Gravity played a very vital role in the formation of the universe, all the celestial bodies in here, the galaxies and the stars and planets within this galaxies. We will also mention it often on the next discussion which is the formation of the solar system. But this time, bear in mind that gravity governs everything in the universe even it is the weakest of all the four forces in nature and according to Newton’s universal Law of gravitation, it causes two bodies with mass to be attracted to each other. Protostar is considered as the future star and the early stage in star formation (Zuckerman, 2019) As time passes, the protostar attracts more gas and grows hotter. Upon reaching its ideal temperature, it starts to initiate nuclear fusion which is mentioned on the last evidence of Big bang. Nuclear fusion happens when Hydrogen atoms in the interior begin to fuse producing Helium atoms and an outflow of energy (Padua et al., 2016). Depending on the mass of stars, fusion will continue until the star produce heavier Figure 1.25 Taurus molecular cloud elements in its core. where the birth of protostars take place Main sequence stars like the sun undergo this type of Photo credit: NASA Astrobiology atomic reaction that serve as its source of energy. 12 Earth Science One question here is that how the stars manage to keep their balance and not collapse in their lifetime? The answer to this question is a special interaction between gravity and pressure of the star! Gravity pushing the material inward counterbalances the outward pressure of gas created by energy in nuclear fusion results in Figure 1.26 shows the balance stabilities within the star (Lamb, 2010) between gravity and pressure that This equilibrium between gravity and pressure maintains the star’s stability prevents the star from collapsing or blow apart. Photo credit: David Darling, 2016 What is the fate of our sun and how long will the series of thermonuclear reactions continue? Figure 1.27 shows life cycle of a star from a stellar nebula. The fate of the star depend on its size. Photo credit: NASA Average or main-sequence stars like the sun proceeds on being a red giant on its dying stage then a planetary nebula and a white dwarf on its dying stage. Stars that are massive than the sun turns into a red supergiant which eventually dies into a cataclysmic explosion, being a supernova. Supernova are the source of elements here on the universe and as its explode, its remnants will become the future stars, planets, and galaxies (Padua et al., 2016) “We are dead stars.Everything we are – the iron in our blood, every element we’ve ever heard of – is made from a star, a dust cloud collapsing under the force of gravity. - Dr. Michelle Thaller Remember, next time when you start doubting yourself that you are a part of something big and that the whole universe is inside you. There Is more to discover in you like the hidden mysteries of the cosmos. 13