Q&A Hero

Q: Fusion in giant stars takes us all the way to iron before a Type II supernova occurs. Why did it stop with helium in the far more energetic Big Bang?

Q: Quasars are far more luminous than Type I supernovae; why not use them to calibrate Ho and the age of the universe?

Q: Contrast the roles of dark matter and dark energy in the fate of the cosmos.

Q: Can either normal or dark matter stop the universal expansion?

Q: Why were Type I supernovae so critical in discovering dark energy?

Q: Galaxies in all directions appear to be red shifted, as if rushing away from us in the center of the universe. How does the cosmological principle handle this problem?

Q: Why did Hubble conclude the universe must be expanding?

Q: What satellite revealed the most about cosmology, and why was it so effective?

Q: Why was the separation of the superforce into three forces so important?

Q: Regular atoms did not show up in the universe until when?

Q: Why do population II stars contain almost nothing but hydrogen and helium?

Q: Why were elements heavier than helium not produced during the Big Bang?

Q: What role did Princeton astronomers play in the research on the Big Bang?

Q: Why was the 1978 Nobel Prize in Physics given to Penzias and Wilson from Bell labs?

Q: When dark matter was first discovered, some astronomers thought that Ωo was greater than one from the extra gravity, favoring what type of universe?

Q: Contrast the original and present uses of the Cosmological Constant.

Q: How does dark energy affect the expansion of the universe?

Q: How would the geometry of a universe with Ωo greater than 1 differ from one with Ωo less than 1?

Q: If the density is less than critical, which fate of the universe awaits us?

Q: Is the Hubble constant really constant?

Q: What would the geometry of a universe at the critical density be?

Q: Discuss the value of Ho if the universe were closed and starting to collapse.

Q: Relate the age of the universe to the Hubble constant.

Q: Is the cosmological red shift really a velocity of a given galaxy?

Q: Does the universe have an edge or a center?

Q: State the cosmological principle.

Q: What is the study of cosmology?

Q: The COBE data, combined with computer simulations, strongly supported the ________ Epoch, showing how ripples in the background radiation could collapse into galaxies over time.

Q: The ________ epoch explains the isotropy of the cosmic microwave background mapped by COBE.

Q: The ________ epoch happened when the superforce separated into the electromagnetic, strong, and weak forces, with a tremendous release of pressure.

Q: The universe is dominated by dark ________.

Q: At a temperature of ________, protons and neutrons combined to form deuterium and start cosmic nucleosynthesis.

Q: Helium production ceased when the universe was about ________ minutes old, and did not resume until the first generation of stars formed.

Q: The primordial nucleosynthesis was sped up by the abundance of ________ in the universe once the temperature dropped below a billion K.

Q: After the decoupling, the universe was ________ to radiation.

Q: When decoupling occurred ________ formed.

Q: Prior to decoupling, all matter was ________, with free electrons and nuclei.

Q: When the universe was several hundred thousand years old, matter and energy decoupled, allowing the ________ radiation to escape, expand and cool off.

Q: The discovery of the ________ at Bell Labs strongly supported the Big Bang.

Q: The universe we live in now is said to be ________ dominated.

Q: The microwave background we now observe dates back to ________ of matter and energy at 3,000 K.

Q: The satellite most critical to the study of the formation and structure of the universe is ________, which detected the ripples that led to galaxies.

Q: In 1998 came the discovery of ________, which seems to overwhelm even gravity and all the dark matter in the final fate of the cosmos.

Q: If Ωo is exactly one, then the geometry of the universe is ________.

Q: The inclusion of all known dark matter still increased the density to only ________ of the critical density.

Q: The discovery of dark energy increased support for the ________ universe.

Q: Einstein's ________ constant has been revived to help us explain dark energy.

Q: Since the finding of dark energy, almost all data supports a(n) ________ universe.

Q: The critical density must include both matter and ________.

Q: The latest observations suggest the ratio of matter to energy is about ________.

Q: The universe's density, compared to the critical density, determines the ________ of space.

Q: The infinite, open universe has a geometry compared to the surface of a ________.

Q: The closed universe is compared to the surface of a ________ in spacetime.

Q: The relation between the Doppler shift of galaxies and their distances is called ________.

Q: The hot, dense universe shortly after the Big Bang is referred to as the ________.

Q: The critical number for the rate of universal expansion and age of the Big Bang is ________.

Q: ________ paradox asks why the sky is dark at night.

Q: The assumption that from any place in the universe the observer would measure the same physical properties we observe is called the ________.

Q: In the cosmological principle, ________ implies that the direction the observer faces makes no difference on the grandest scale.

Q: In the cosmological principle, ________ implies that matter and energy are randomly distributed in space.

Q: The tiny ripples in the background radiation COBE found are due to A) a gravitational redshift caused by growing dark clumps. B) different velocities of the edge of the universe. C) reddening by interstellar dust clouds in our galaxy. D) variations in the speed of different wavelengths of light. E) bubble-like nature of space.

Q: In 1992, COBE observations revealed A) that the universe had less than the critical density, so was open. B) the microwave background radiation is not isotropic, but centered on Virgo. C) the dark matter in the universe is normal (baryonic), so the universe is closed. D) there are small ripples in the microwave background, the seeds of galaxies. E) the existence of dark energy.

Q: The satellite that found the ripples in the cosmic background that led to galaxies is A) SOHO. B) the Hubble Space Telescope. C) the Chandra X-Ray Observatory. D) COBE. E) the Compton Gamma Ray Observatory.

Q: In the Grand Unified Theory, the superforce was A) only dark energy. B) a union of the weak and electromagnetic forces. C) a union of all matter and energy. D) a union of the strong and weak nuclear, and electromagnetic forces. E) was only in effect at low energies.

Q: The best answer to both the flatness and horizon problems is A) the Steady State Theory. B) the GUT theory. C) the inflationary epoch. D) dark energy. E) decoupling.

Q: The 3 K background radiation represents A) the Big Bang itself. B) the time of decoupling. C) the formation of the first galaxies. D) the outer edge of the universe. E) formation of the first quasar.

Q: Why didn't elements heavier than helium form in the first minutes of creation? A) The first generation of stars used them up too quickly to observe them. B) There was not enough matter in the universe at that time. C) When He-4 was formed, the expansion cooled the cosmos below 100 million K. D) The electrons slowed down enough to be captured into orbits by protons. E) Only Type I supernovae can produce iron and heavier elements.

Q: Most of the deuterium formed right after the Big Bang A) is still around today. B) broke down into electrons and neutrons. C) turned into dark matter. D) quickly burned into helium nuclei. E) was found in the globular clusters.

Q: Before the decoupling, A) the universe was transparent to radiation. B) the universe was opaque to radiation. C) protons and electrons combined to form atoms. D) there was more helium than hydrogen. E) deuterium produced electrons and positrons.

Q: The Big Bang formed A) only hydrogen. B) only helium. C) hydrogen and helium, but very little else. D) all elements up to iron. E) all elements found in nature now.

Q: What key event happened during the decoupling epoch? A) Pairs of neutrons and protons were created. B) Electrons and positrons were created. C) Expansion cooled the universe enough that protons could capture electrons in orbit. D) Dark energy accelerated the cosmos on to infinity. E) The universe underwent a brief period of very rapid expansion.

Q: Concerning dark energy, we do know A) that it is created when matter annihilates anti-matter. B) its density remains constant over time, so it is not important in the early universe. C) combined with dark matter, it will ultimately produce a closed universe. D) that it was revealed with Type II supernovae distances in the late 1990s. E) that it makes up 90% of all the matter and energy in the whole universe.

Q: How does the energy of the cosmic microwave background compare to the energy radiated by all the stars and galaxies that ever existed? A) They are very close to being equal. B) 73% cosmic background, 27% starlight C) about ten times more from the Big Bang than from stars and galaxies D) The starlight now dominates the background, as your eyes show clearly. E) We have no way of comparing matter and energy this way.

Q: The discovery of the cosmic microwave background was important because A) it established a firm center of the universe. B) it was experimental verification of a prediction from the Big Bang theory. C) it proved that astronomy at radio wavelengths was possible. D) its detection was a major advance in microwave testing. E) it showed the universe must be closed, with more than the critical density here.

Q: What temperature has the Big Bang cooled to by now? A) about 3,000 K B) 5,800 K C) about 300 K D) just over 2.7 K E) 1.4 K

Q: The major players in the discovery of the cosmic microwave background were at A) Cal Tech and Mt. Palomar. B) Jet Propulsion Lab and MIT. C) Bell Labs and Princeton. D) Kitt Peak and the University of Arizona. E) Keck telescopes and the University of Hawaii.

Q: In the critical density universe now proposed, the ratio of dark energy to matter is about A) 1 to 100. B) 1 to 1. C) 3 to 1. D) 10 to 1. E) 1 to 5.

Q: The expansion rate of the universe is A) increasing. B) decreasing. C) constant. D) different in different directions. E) independent of time.

Q: According to the turn-off points of the oldest globular clusters, they are about A) 4.5 billion years old. B) 6.8 billion years old. C) 10 billion years old. D) 12 billion years old. E) 16 billion years old.

Q: Studies from ________ led to the discovery of "dark energy." A) Cepheid variables in the Virgo Cluster B) Type II supernovae in the Large Magellanic Cloud C) the gravitational lensing by MACHOs D) the COBE microwave ripples E) Type I supernovae at very large red shifts