Big Bang Theory Assignment

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Plymouth State University *

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Astronomy

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Jan 9, 2024

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Name: _________________________________ Date: ________________ Lesson 26.3: The Universe CK-12 Assignment (50 points) True or False Write true if the statement is true or false if the statement is false. Put a “T” for a true statement and a “F” for a false statement. _T____ 1. Hubble was the first scientist to discover that the universe is much larger than our own galaxy. __T___ 2. Today we know that there are as many galaxies in the universe as there are stars in our galaxy. ___F_ 3. The existence of redshift demonstrates that other stars in the Milky Way Galaxy are moving away from our solar system. __F__ 4. Evidence has proven conclusively that the Big Bang theory is correct. __F___ 5. Scientists think that light-emitting objects now make up most of the matter in the universe. __F___ 6. Dark matter has no mass so it has no gravity. __F___ 7. Most astronomers think that the universe will expand more slowly in the future than it is expanding now. ___T__ 8. Some scientists estimate that there is currently more dark energy than ordinary energy in the universe. __T___ 9. Gravitational lensing provides evidence for the existence of dark matter. __T___ 10. A similar principle explains both redshift and the Doppler effect. Lesson 26.3: Critical Reading Read this passage based on the text and answer the questions that follow. Formation of the Universe The Big Bang theory is the most widely accepted cosmological explanation for how the universe formed. According to the Big Bang theory, the universe began about 13.7 billion years ago, before which everything in the universe was squeezed into a very small volume. This means that at the beginning, the entire known universe was a single, hot, chaotic mass. Then, an enormous explosion — a big bang — caused the universe to start expanding rapidly. According to the Big Bang theory, all of the matter and energy in the universe, and even space itself, came out of this explosion. In the first few moments after the Big Bang, the universe was unimaginably hot and dense. As the universe expanded, it became less dense and began to cool. After only a few seconds, protons, neutrons, and electrons began to form. After a few minutes, protons and neutrons came together to create hydrogen
nuclei. Energy in the universe was great enough to initiate nuclear fusion, and hydrogen nuclei fused together to become helium nuclei. However, the first neutral atoms (atoms that included electrons) did not form until about 380,000 years later. Scientists think that matter in the early universe was not evenly distributed across space. Instead, there existed dense clumps of matter held together by gravity. Eventually, these clumps became the countless trillions of stars, billions of galaxies, and other structures we now know to make up the visible mass of the universe. When it was first proposed, the Big Bang theory was just a hypothesis. Many astronomers did not accept it and thought that the universe was static. However, nearly all astronomers came to accept the hypothesis when an important line of evidence for the Big Bang was discovered in 1964. After that, the Big Bang hypothesis achieved the status of a scientific theory. Two researchers at Bell Laboratories, using a microwave receiver, learned that the background radiation of the universe gave space a temperature of 3 Kelvin, not 0 Kelvin, which would be expected in a static universe. Although this is a small amount of heat, it was enough for most scientists to agree that it must be left over from the Big Bang. Questions 1. What is the Big Bang theory? Answer: The Big Bang theory is the most widely accepted cosmological explanation for how the universe formed. According to the Big Bang theory, the universe began about 13.7 billion years ago, before which everything in the universe was squeezed into a very small volume. 2. Outline the events that occurred after the initial big bang. Answer: After a few seconds: - protons, neutrons and electrons began to form. - After a few minutes: protons and neutrons came together to create hydrogen nuclei - 380,000 years after: the first neutral atoms that included electrons - They then formed dense clumps of matter held by gravity that eventually the trillions of stars, galaxies and other structures 3. What evidence convinced most astronomers that the Big Bang hypothesis should be considered a scientific theory? Answer: When in 1964 two researchers at Bell Laboratories using a microwave receiver learned background radiation of the universe gave space a temperature of 3 Kelvin, not 0 Kelvin. Lesson 26.3: Multiple Choice Highlight the letter of the correct choice. 1. Dark bands in the spectrum of light from a star show where elements in the star ________. a. absorb light b. reflect light c. refract light d. shift light 2. What occurs as the universe expands? a. Solar systems get larger
b. Galaxies increase in size c. The space between galaxies increases d. all of the above 3. Prior to their acceptance of the Big Bang theory, most astronomers thought that the universe was ________. a. unchanging b. growing bigger c. shrinking in size d. alternately contracting and expanding 4. After the Big Bang occurred, scientists think that the universe ___________. a. started to expand b. grew less dense c. began to cool d. all of the above 5. How do scientists know that dark matter exists? a. Its heat raises the temperature of space b. Its gravity affects objects around it c. It gives off electromagnetic waves d. all of the above 6. Astronomers have discovered recently that the rate at which the universe is expanding is ______. a. increasing b. decreasing c. staying the same d. impossible to determine 7. Massive astrophysical compact halo objects (MACHOS) include objects in _________. a. black holes b. neutron stars c. white dwarfs d. two of the above Lesson 26.3: Matching Fill in the blank with the appropriate term. Definitions __E___ 1. all the matter, energy, space, and time that ever existed and will ever exist ___A__ 2. observation that more distant galaxies are moving away from us more quickly than closer galaxies __G___ 3. change in the color of light absorbed by an object as it moves away from an observer __C___ 4. proposed form of energy that we currently are unable to detect
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