ESCI Lesson 1 Origin of the Universe.pdf

Earth Science Lesson 1: Origin and structure of the Planet Earth Learning Competency: State the different hypotheses explaining the origin of the universe. (S11/12ES-Ia-e-1) Lesson Objectives: Describe the structure and comp...

Earth Science Lesson 1: Origin and structure of the Planet Earth Learning Competency: State the different hypotheses explaining the origin of the universe. (S11/12ES-Ia-e-1) Lesson Objectives: Describe the structure and composition of the Universe; State the different hypothesis that preceded the Big Bang Theory of the Origin of the Universe. Explain the red-shift and how it used as proof of an expanding universe. Structure, Composition and, Age of the Universe The universe as we currently know it comprises all space and time, and all matter and energy in it. It is made of 4.6% baryonic matter (“ordinary” matter consisting of protons, electrons, and neutrons: atoms, planets, stars, galaxies, nebulae, and other bodies), 24% cold dark matter (matter that has gravity but does not emit light), and 71.4% dark energy (a source of anti-gravity). Hydrogen, helium, and lithium are the three most abundant elements. Stars - the building block of galaxies-are born out of clouds of gas and dust in galaxies. Instabilities within the clouds eventually results into gravitational collapse, rotation, heating up, and transformation into a protostar-the hot core of a future star as thermonuclear reactions set in. Birth, evolution, death, and rebirth of stars The remaining dust and gas may end up as they are or as planets, asteroids, or other bodies in the accompanying planetary system. A galaxy is a cluster of billions of stars and clusters of galaxies form superclusters.  Based on recent data, the universe is 13.8 billion years old. The diameter of the universe is possibly infinite but should be at least 91 billion light-years (1 light-year = 9.4607 × 10^12 km). Its density is 4.5 x 10^-31 g/cm3. Stellar interiors are like furnaces where elements are synthesized or combined/fused together. Most stars such as the Sun belong to the so-called “main sequence stars.” In the cores of such stars, hydrogen atoms are fused through thermonuclear reactions to make helium atoms. Theories of the Origin of the Universe The Big Bang Theory Description: The most widely accepted theory, the Big Bang suggests that the universe began as an extremely hot, dense point about 13.8 billion years ago. This point rapidly expanded in a massive explosion, leading to the formation of matter, space, and time. As the universe expanded, it cooled, allowing particles to combine and form atoms, leading to the formation of galaxies, stars, and planets. Supporting Evidence: Cosmic Microwave Background Radiation (CMB), redshift of galaxies, and the abundance of light element Cosmic Microwave Background Radiation (CMB) Origin: The CMB originated about 380,000 years after the Big Bang when the universe cooled enough for protons and electrons to combine into neutral hydrogen atoms. This process, known as "recombination," allowed photons (light particles) to travel freely through space Discovery: The CMB was accidentally discovered in 1965 by Arno Penzias and Robert Wilson, who were awarded the Nobel Prize in Physics for their work. Their discovery provided strong evidence for the Big Bang Theory. Uniformity and Anisotropies: The CMB is remarkably uniform in all directions, but it contains tiny fluctuations or anisotropies. These small variations in temperature and density provided the seeds for the formation of galaxies and large-scale structures in the universe. Redshift refers to the phenomenon where the light or other electromagnetic radiation from an object, such as a star or galaxy, is shifted towards the red end of the spectrum as it travels through space. This shift occurs because the object is moving away from the observer, causing the wavelengths of light to stretch out, or "shift" to longer wavelengths, which are in the red part of the spectrum. In 1929, Edwin Hubble, He observed that spectral lines of starlight made to pass through a prism are shifted toward the red part of the electromagnetic spectrum, i.e., toward the band of lower frequency; thus, the inference that the star or galaxy must be moving away from us. Steady State Theory Description: Proposed in 1948 by Fred Hoyle, Thomas Gold, and Hermann Bondi, the Steady State Theory posits that the universe has always existed in a constant state and has no beginning or end. It suggests that as the universe expands, new matter is continuously created to maintain a constant density. Supporting Evidence: The theory was popular in the mid-20th century but lost support after the discovery of the CMB and other observations consistent with the Big Bang Theory. Inflationary Theory Description: An extension of the Big Bang Theory, proposed by Alan Guth in 1981, the Inflationary Theory suggests that the universe underwent an exponential expansion in the first tiny fraction of a second after the Big Bang. This rapid inflation solved several problems in the standard Big Bang model, such as the horizon and flatness problems. Supporting Evidence: The theory explains the uniformity of the CMB and the large-scale structure of the universe. 4. Multiverse Theory Description: The Multiverse Theory suggests that our universe is just one of many universes that exist simultaneously. These universes may have different physical laws and constants. This idea is often tied to theories in quantum mechanics and string theory. Supporting Evidence: The theory explains the uniformity of the CMB and the large-scale structure of the universe. 5. Oscillatory Universe Theory Description: This theory proposes that the universe undergoes infinite cycles of expansion and contraction. After each Big Bang, the universe expands, but eventually, gravitational forces cause it to contract in a "Big Crunch," leading to another Big Bang, and the cycle repeats. Supporting Evidence: Some models of string theory and quantum gravity suggest that such a cyclical process could be possible, though there is no direct observational evidence.