Chapter 18

Which of the following is/are not considered direct evidence for the Big Bang? Choose all that apply. a. the existence of black holes b. the expansion of the Universe c. the primordial abundance of elements d. the presence of life in the Universe e. cosmic microwave background radiation

Which of the following statement(s) accurately state(s) ways in which Big Bang nucleosynthesis differed from nuclear fusion in stars? Choose all that apply. a. Its duration was a tiny fraction of time over which nuclear fusion has occurred in stars. b. It produced fewer elements and isotopes. c. It was incapable of producing carbon. d. It resulted in the production of hydrogen. e. The temperature was falling as nuclear fusion began.

Which of the following statements about space-time in our Universe is not correct? a. Evidence suggests that it is finite and bounded. b. It constitutes a four-dimensional continuum. c. It was first recognized as a unified quantity within special relativity d. There is a limit to its expansion. e. There is strong evidence to suggest its current geometry.

Which of the following was/were "steady" according to Hoyle's steady-state model? a. the amount of matter b. the amount of space c. the average cosmic density d. the distance between any two galaxies e. all quantities and measurements

Which particle carries the strong nuclear force? a. photon b. quark c. gluon d. newton e. graviton

Which of the following statements is false? a. The tau lepton carries the electromagnetic force. b. The photon is a force boson. c. \(W\) and \(Z\) bosons carry the weak nuclear force. d. The muon is a lepton. e. Gravitons are hypothesized to carry the gravitational force.

Which of the following does not describe conditions since shortly after the Big Bang? a. Temperature and density have decreased. b. The volume of space-time has increased. c. The overall size of the Universe has increased. d. Inflation occurred and ended. e. Initial perturbations have been mostly smoothed away

Cosmic inflation refers to a. the Universe filling up with hydrogen gas. b. the ongoing expansion of the Universe. c. a brief early period of hyperrapid expansion of space-time. d. the current period of cosmic acceleration. e. stellar winds creating bubbles of gas.

How long after the Big Bang was the primordial abundance of elements established? a. It is still changing today. b. \(10^{-33}\) second c. 0.001 second d. 3 minutes e. 380,000 years

Which of the following statements about the CMB is/are not true? Choose all that apply. a. Its photons originated at the moment of the Big Bang. b. Its photons have been redshifted dramatically since their creation. c. Its current temperature is \(2.7 \mathrm{K}\) d. It is a blackbody. e. It is completely homogeneous in temperature.

Inflation theory helps explain many current properties of the Universe. Which of the following cannot be attributed to it? Choose all that apply. a. It drives the value of \(\Omega\) toward 1 b. It accounts for the size and strength of perturbations. c. It explains why the Big Bang occurred. d. It explains the primordial abundance of elements. e. It explains why different sides of the sky show the same CMB fluctuations.

Dark energy accounts for a. 30 percent of the matter and energy in the Universe. b. a percentage of the matter-energy in the Universe that is less than dark matter but more than luminous matter. c. a percentage of the matter-energy in the Universe that is more than dark matter but less than luminous matter. d. a percentage of the matter-energy in the Universe that is more than dark matter and luminous matter combined. e. inflation.

Ignoring the effect of dark energy, a value of \(\Omega\) greater than 1 a. would be impossible. b. would mean the Universe will eventually contract. c. would mean there is more luminous matter than dark matter. d. would mean the Universe will expand at an ever-increasing rate forever. e. is what astronomers believe is the actual value of \(\Omega\).

Which of the following is true about the era of recombination? a. It was the period when photons could not escape. b. It occurred within seconds of the Big Bang. c. It was marked by the re-creation of \(\mathrm{H}\) atoms from component parts that had been separated long before. d. It marked the release of the CMB. e. It smoothed out perturbations in the dense matter-energy.

Which of the following statements about dark matter and dark energy is/are true? Choose all that apply. a. While the nature of dark matter has been determined, the nature of dark energy has not. b. The effect of dark energy is observed only on cosmological scales, while the effect of dark matter has been observed on the scale of galaxies. c. Both far exceed the matter-energy equivalent of luminous matter. d. Evidence for the existence of dark energy was identified first. e. Dark matter has only an attractive gravitational effect, while dark energy is repulsive.

Which of the following describes commonalities between the periods of Big Bang nucleosynthesis and recombination? a. average temperature b. duration of the period c. size of the Universe d. initial formation of a new configuration of matter e. release of photons

True/False: The Universe is continuing to cool today.

True/False: The primal abundance of elements provides evidence for the Big Bang by indicating that the Universe was briefly hot enough for nucleosynthesis to occur.

True/False: A fully developed theory uniting all four fundamental forces has yet to be defined.

How did the term Big Bang come into being?

Describe what is meant by positive, negative, and flat curvature.

What are the two classes of fundamental matter particles? What distinguishes the two classes?

Which force boson carries the electromagnetic force? the weak nuclear force? the strong nuclear force?

What are the proportions of hydrogen and helium in the primordial abundance of elements? Why were heavier elements not formed during Big Bang nucleosynthesis?

Describe the differences between the steady-state model and the Big Bang model.

Recall your view of the origin, scope, and age of the Universe before you began this course. How has it changed (if at all) during this course?

What value would you expect for the peak wavelength of the CMB if the Universe had expanded by a factor of 800 since recombination?

By what factor had the Universe expanded since recombination when the peak wavelength of the CMB was 0.00038 meter?

What do you expect the temperature of the CMB to be when the Universe has expanded to 1.5 times its current size?

The discovery of dark energy was based on the variation of the observed brightness of Type Ia supernovas to their expected brightness. Comparing two such supernovas, A and B, what would be the expected ratio of A's brightness to that of \(\mathrm{B}\), if \(\mathrm{A}\) is \(1 / 7\) th as far from Earth as B?