Aadi Ganguli
Cannistraro
AR 8 - 1st Hour
01 April 2023
The Origin of the Universe and Its Makeup
INTRODUCTION
"In the universe, there are things that are known, and things that are unknown, and in between, there are doors" (Blake). This quote by William Blake brings light to scientific work contributing to humankind's knowledge of the universe. Much of the work remains theoretical, but the goal of these scientists remains the same. It is to learn about the rapidly growing universe. As scientists' research of the universe continues, they create theories and conduct tests to understand its true nature.
ORIGINS OF THE UNIVERSE
There were several events before and after the Big Bang that are not well known. Before the Big Bang, everything was consolidated into a single point called a singularity which had infinite density (Wilson). During the Big Bang, the universe started inflating at an extremely fast pace around 13.7 billion years ago (Wall, Pultarova). After the Big Bang, atoms started forming 380,000 years after the Big Bang ("The early universe"). Though scientists know more about the events during and after the Big Bang, they are still researching what the universe was like before that event.
Although scientists have an idea of how the universe was born, the events that transpired before the Big Bang are still being studied. Before the Big Bang, the universe was consolidated into a singular point called a singularity which had infinitely hot temperatures. Singularities are any point in space where a property is infinite. For example, a black hole is a singularity because it has an infinite density. The state of the universe was quantum fluctuation before the Big Bang ("Singularities and Black Holes"). This implies that the universe underwent a cosmic expansion even before the Big Bang. Over 80 times the size of the Universe doubled in less than a second (Hsu). All of the universe's matter, both present and future, made up the singularity. Everything was cramped into a single, unimaginably hot point until it blew outwards in what humankind knows as the Big Bang ("How did the universe begin? How will it end?"). Although most scientists agree that the universe started as a singularity, they are still attempting to determine what caused the Big Bang and why.
A century ago, the Big Bang Theory was conceived, and it took forty years of study to prove it. Georges Lemaître developed the Big Bang theory. Georges lived from 1894-1966. He was a Belgian Cosmologist and a Catholic priest ("Georges Lemaître, Father of the Big Bang"). He created the theory in the 1920s. Georges theorized that the universe began from a single atom, which would later be called a singularity. This theory was majorly supported by Edwin Hubble's observation that galaxies were speeding away from Earth in all directions (Greshko). In 1964, the theory was validated. In 1964, researchers made the Cosmic Microwave Background (CMB) discovery. The Big Bang was confirmed by CMB to be the most reliable theory for how the universe originated. This is because CMB is the cooled remnant of the first light ever to have traveled across the universe. Scientists tested this theory for several years and concluded that the theory was correct ("Big Bang"). The cause of the Big Bang is not known, but most scientists agree that the universe is still expanding at a rapid rate.
Cosmic inflation was a period in time when the universe grew exponentially, doubling in size eighty times in under a second. Cosmic inflation was the universe's exponential growth period. It is theorized to have lasted from seconds to around or seconds. In the 1970s to 1980s, the theory was developed with contributions from many theoretical physicists. Wikipedia states that these people contributed to the theory. "Alexei Starobinsky at Landau Institute for Theoretical Physics, Alan Guth at Cornell University, and Andrei Linde at Lebedev Physical Institute. Alexei, Alan, and Andrei won the 2014 Kalvin Prize for 'pioneering the theory of Cosmic Inflation'" ("Inflation (cosmology)"). A problem that was solved with the theory is the flatness question. This was solved by growing the initial, singularity universe out of any curves it had. This was done in the same way a ball loses curvature when it becomes flattened. It also explains how the universe grew so quickly from a single point into the universe today ("Inflation"). The Big Bang was the turning point for the universe and helped it to become habitable, but first, it needed to cool down.
Atoms could not form until the universe cooled enough, 380,000 years later. The Universe was too hot and too dense after the Big Bang for atoms to develop. Hydrogen did not develop until the universe had subsequently spread out and cooled down. Around and seconds later after the Big Bang, some subatomic particles formed. These were neutrinos, quarks, and electrons. Protons and Neutrons formed shortly after from the Neutrinos and Quarks, around seconds to one second after the Big Bang. Within three minutes after the Big Bang, conditions became suitable for elements to form, and protons and neutrons came together to form the first hydrogen nuclei. Some nuclei came together to form helium. This stage was called nucleosynthesis. However, after 20 minutes, nucleosynthesis ended and no other nuclei could form. Electrons could not stay in orbit of the nuclei because of the extreme heat and radiation still in the universe. Shortly after any neutral atoms could form (atoms with the same amount of protons and neutrons, thus giving them no charge), they were blown apart by energetic radiation (Ye). Although neutral atoms were formed soon after the Big Bang, elemental atoms needed another 380,000 years to develop.
Similar to atoms, molecules could not form until 380,000 years later, when the cosmos began to expand and cool. Before the cosmos cooled enough for electrons to orbit the protons and neutrons and give them charge, molecules had not yet formed. The first molecule was created by the two elements at the time, hydrogen and helium. These combined to form a helium hydride molecule. This molecule is present in several celestial bodies like stars and some gas-based planets. Before molecules could form, the universe had to cool down 380,000 years after the Big Bang. Even then, only a couple could form without being blown apart by radiation and energy. The universe needed to expand enough so that the nuclei could capture electrons and become atoms instead of neutral atoms (neutral atoms are atoms with the same amount of protons and neutrons, thus giving them no charge) (Bell, Hawkes). After molecules formed, they banded together to create more complex molecules, and after a couple of million years, celestial bodies were created.
MAKEUP OF THE UNIVERSE
Multiple celestial bodies exist in the universe, however, there are many types, each with its complexities. Celestial bodies are the different objects that can occur naturally in the universe. There are celestial bodies and celestial objects, which are different in one way. The difference is celestial bodies are singular objects, such as asteroids or planets. Celestial objects are complex systems such as solar systems or asteroid belts. There are several different types of celestial bodies, like suns, nebulae, asteroids, and comets. As the universe is expanding, more celestial bodies and objects are being born ("Astronomical object"). Celestial bodies are not limited to stars, planets, and asteroids; there are undoubtedly undiscovered bodies in the universe.
Nebulae are large dust clouds that can stretch to the size of a galaxy, and create beautiful patterns in the night sky. The definition of a nebula is "a distinct luminescent part of interstellar medium, which can consist of ionized, neutral or molecular hydrogen and also cosmic dust" ("Nebula"). ("Nebula"). Nebulae have the ability to create other celestial bodies, including stars and some planets.
Stars have an interesting life cycle in which they die and turn into the celestial body that creates them. The definition of a star is, "an astronomical object comprising a luminous spheroid of plasma held together by self-gravity" ("Star"). A star is born when a nebula gravitationally collapses into itself. Stars generate energy by fusing hydrogen and helium in their core. When the two elements combine, they create a chemical reaction that causes heat ("Star"). Although stars form only one way, a star can die in multiple ways. If the star is not large enough to become a black hole or neutron star, the star will run out of material to burn in its core, and it will lose energy and heat. As a result, it does not have enough energy to collapse, so it becomes extremely dense due to electron degeneracy pressure. However, usually, a mid-sized star will have enough energy to turn into a red giant, which is the last stage in its life. During its death, it collapses on itself gravitationally. When this happens, it expels all of its matter outwards. This is called a supernova ("White dwarf"). When stars die, they may turn into a nebula or, if large enough, a black hole.
Several planets exist outside of the Milky Way, yet there are only two types that scientists know about terrestrial and gaseous. From Nasa.gov's perspective, a planet "must orbit a star (in our cosmic neighborhood, the Sun). It must be big enough to have enough gravity to force it into a spherical shape. It must be big enough that its gravity cleared away any other objects of similar size near its orbit around the Sun" ("Planets"). The fittest theory for planetary formation is called "nebular hypothesis". This states that a "clump" of a nebula collapses and forms a star with an orbital disk around it. Planets form in this disk by the gradual accumulation of material from gravity ("Planet"). There are only two main types of planets. There are gaseous planets which are mainly composed of helium and/or hydrogen. Usually, there is nitrogen as well. The other type of planet is a terrestrial planet, which has rock and land. These planets are usually much smaller than gas planets and have multiple layers of rock. Some terrestrial planets farther away from the sun will have water, or ice depending on the location of the planet ("Gas Giant"). Scientists know several properties planets have, however, their properties remain unknown due to their distance from Earth.
Singularities exist in space-time only as points that have infinite density and attract everything to them. A spacetime singularity, also known as a gravitational singularity, is a situation in which it is projected that gravity would be so strong that spacetime will inevitably collapse catastrophically. This means that spacetime collapses into nothing due to the intense gravitational pull. As a result, a singularity is not a part of normal spacetime, and cannot be located by "where" or "when". There are various types of singularities in the universe. The main type of singularity is a black hole. Black holes form after the death of a star, when it gravitationally collapses on itself. The force and energy that is created give it infinite density and mass. The universe is theorized to have started as a singularity, before the Big Bang ("Gravitational singularity"). The closest black hole to Earth is called Gaia BH1. It is just under 1,600 light years away from the earth. The Milky Way is thought to have hundreds of millions of singularities, but only a couple have revealed themselves due to radiation and light around them ("Sun-like star found orbiting closest black hole to Earth"). Singularities are used to describe a variety of phenomena in the world, such as the universe before the Big Bang.
END OF THE UNIVERSE
Dark energy and dark matter are still being investigated, but there is an abundance of evidence to support them. Black matter is a substance estimated to make up 85% of the universe. It is called "dark" matter because it cannot be detected by the electromagnetic field, meaning it does not absorb, reflect, or emit electromagnetic radiation ("Dark matter"). Astronomers define dark energy as an as-yet-undiscovered type of energy that has the potential to significantly impact the universe. Supernova observations displayed that the cosmos are not expanding swiftly but rather at an accelerating rate. Scientists use dark energy and dark matter to explain how the universe is expanding, and how it might end. Scientists still do not know for sure if they are indeed real, but they have several solid theories surrounding them ("Dark energy"). The cosmos is made up of dark energy and dark matter, which also fuel its ongoing expansion.
The Big Freeze (Heat Death) theory was created to predict the end of the universe, and it is currently the best theory. The Heat Death theory theorizes that the universe will evolve to a state of no thermodynamic free energy, and therefore will not be able to sustain processes that can create bodies and objects in the universe ("Heat death of the universe"). This just means that the matter and energy will dissipate until the universe has become so disordered that entropy, or the randomization of celestial bodies, stops and all activity comes to an end ("WHAT IS ENTROPY? PART 3: THE WAY THE UNIVERSE WILL END"). In 1851, Lord Thomas Kelvin first created the theory in his book, "On a Universal Tendency in Nature to the Dissipation of Mechanical Energy". He said, "heat is not a substance, but a dynamical form of mechanical effect, we perceive that there must be an equivalence between mechanical work and heat, as between cause and effect". Heat death is theorized to happen at around 1.7×10106 years when protons decay ("Heath death of the universe"). The heat death theory, agreed upon by most scientists, explains that entropy comes to an end, and all celestial bodies die.
The Big Rip theory was developed to explain the end of the cosmos, although most scientists now reject this view. According to the Big Rip theory, the universe's mass, including galaxies and subatomic particles, would steadily be torn apart until the distances between the particles were limitless. The universe would become so big that there would not be enough gravitational force between the particles to hold them together, and they would break apart ("Big Rip"). Dark energy is one of the factors of the universe's exponential expansion. Dark energy will expand the universe to the point of subatomic particles being completely isolated. The Big Rip, if it is a viable theory, has already happened and continues to happen. Dark energy is already expanding the universe, however, it will not take a major effect until another couple hundred billion years (Mack). The Big Rip theory proposes that the universe will expand until subatomic particles are isolated, much like the early years of the universe.
One other notable idea is the Big Crunch theory, caused by dark matter affecting the universe. Wikipedia states, "The Big Crunch is a hypothetical scenario for the ultimate fate of the universe, in which the expansion of the universe eventually reverses and the universe recollapses, ultimately causing the cosmic scale factor to reach zero, an event potentially followed by a reformation of the universe starting with another Big Bang" ("Big Crunch"). This means that particles in the universe will become so dense due to dark matter expanding the universe, that particles such as atoms and molecules start pulling the universe back into itself. This will result in the universe eventually becoming smaller until it becomes a singularity again. The energy caused by this will create another Big Bang. ("Big Crunch"). The person who created the theory was Alexander Freidman. The theory was created back in 1922, by Russian physicist Alexander Freidman. Dark matter is the reason, if the theory is viable, that the universe may end like this. The universe, as it expands, will be filled with more and more dark matter, until the gravitational force of all the matter in the universe will pull everything back together, and end back up in a singularity ("Big Crunch"). According to the Big Crunch idea, the universe's matter will attract one another with a powerful force until the cosmos becomes a singularity once more.
False vacuum decay is used in many fields of science to describe how the universe may end: the Big Slurp theory. False vacuums are vacuums that are relatively stable, but not as stable as they could be. This condition is called metastable. This state may last for a while. However, it will gradually decay into a stable state. This is known as false vacuum decay. This hypothetical false vacuum will attempt to become stable by going from a state of high energy to a state of low energy until it stabilizes into its lowest energy state. In other words, the vacuum will shrink until it stabilizes in the same way a balloon shrinks when the air is let out of it ("False vacuum decay"). This theory proposes that the universe is in one of these false vacuum states and that the false vacuum will attempt to become a true vacuum or move from a state of high energy to one of low energy. This means that the false vacuum around the universe will shrink down until it becomes a single point in space-time. This false vacuum will shrink at the speed of light, destroying anything in its path until it reaches its goal of a low-energy state. False vacuum decay, if it is a viable theory, does not have an estimated time to start. The scary part is that scientists do not know when it will happen. It could already be happening, and humans would not know if it is happening until it is too late ("Ultimate fate of the universe"). The Big Slurp theory suggests that there is a false vacuum around the universe and that it is decaying to achieve its form as a true vacuum, closing in at the speed of light and destroying everything in its path.
CONCLUSION
Scientists study the universe to comprehend the fundamental nature of it and create theories. One of these theories is the Big Bang theory. How the universe began is explained by the Big Bang. The cosmos has been developing and changing ever since the Big Bang. The simplest particles gradually combined to create complex objects such as stars, galaxies, and nebulae. Tracing the origins of the universe and answering questions about the origin of life became crucial to scientists. They also want to know how the universe may inevitably end. Several aspects of the universe are well studied, and others are theoretical, yet in between, there are answers that scientists are trying to find. Overall, astrophysics is a rapidly growing and changing field that strives to learn new information and collect data for the advancement of human knowledge and technology.
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