21st Century Astronomy
6th Edition
ISBN: 9780393428063
Author: Kay
Publisher: NORTON
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Chapter 21, Problem 9QP
To determine
The current Helium abundance is less than the value predicted in Big Bang implies that.
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The age of the universe can be determined if
a.
the universe is flat.
b.
the amount of dark matter in the universe can be accurately determined.
c.
the rate of recession of the galaxies in the Local Group can be accurately determined.
d.
the temperature of the cosmic background radiation can be accurately determined.
e.
the Hubble constant and density of the universe can be accurately determined.
Why does primordial nuclesythesis end about 3 minutes after the Big Bang ?
select one :
a. The number densities of photons is too large at this time and the photons induce fission , stopping nuclei formation
b. The universe is tooo hot at t=3 minutes
c. The number densities of neutrons and protons and other nuclei are too small at this time and fusion fades out .
d. Deuterium has a lifetime of 3 minutes , so after this time no more deuterium survives as it decays away ?
What strong evidence found in the mid-1960s led to wide acceptance of the big bang theory of the universe?
a.
the discovery of antimatter
b.
the discovery of neutrinos
c.
the discovery of Cepheids as standard candles
d.
the discovery of the cosmic background radiation
e.
the discovery of the 21 cm radiation for neutral hydrogen
Chapter 21 Solutions
21st Century Astronomy
Ch. 21.1 - Prob. 21.1CYUCh. 21.2 - Prob. 21.2CYUCh. 21.3 - Prob. 21.3ACYUCh. 21.3 - Prob. 21.3BCYUCh. 21.4 - Prob. 21.4CYUCh. 21 - Prob. 1QPCh. 21 - Prob. 2QPCh. 21 - Prob. 3QPCh. 21 - Prob. 4QPCh. 21 - Prob. 5QP
Ch. 21 - Prob. 6QPCh. 21 - Prob. 7QPCh. 21 - Prob. 8QPCh. 21 - Prob. 9QPCh. 21 - Prob. 10QPCh. 21 - Prob. 11QPCh. 21 - Prob. 12QPCh. 21 - Prob. 13QPCh. 21 - Prob. 14QPCh. 21 - Prob. 15QPCh. 21 - Prob. 16QPCh. 21 - Prob. 17QPCh. 21 - Prob. 18QPCh. 21 - Prob. 19QPCh. 21 - Prob. 20QPCh. 21 - Prob. 21QPCh. 21 - Prob. 23QPCh. 21 - Prob. 24QPCh. 21 - Prob. 25QPCh. 21 - Prob. 26QPCh. 21 - Prob. 27QPCh. 21 - Prob. 28QPCh. 21 - Prob. 29QPCh. 21 - Prob. 30QPCh. 21 - Prob. 31QPCh. 21 - Prob. 32QPCh. 21 - Prob. 33QPCh. 21 - Prob. 34QPCh. 21 - Prob. 35QPCh. 21 - Prob. 36QPCh. 21 - Prob. 37QPCh. 21 - Prob. 38QPCh. 21 - Prob. 39QPCh. 21 - Prob. 40QPCh. 21 - Prob. 41QPCh. 21 - Prob. 42QPCh. 21 - Prob. 43QPCh. 21 - Prob. 44QPCh. 21 - Prob. 45QP
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- I. NUCLEAR EQUATION: You are going to write the nuclear equations for the following fusion reactions responsible for the abundance of lighter nuclei in the universe. 1. Fusion of two Deuterium isotopes to form Helium3 2. Fusion of Deuterium and a neutron to form Tritium 3. Fusion of Deuterium and a proton to form Heliumarrow_forwardThe density of the universe is a. equal to the critical density if the universe is closed. b. equal to the critical density if the universe is flat. c. greater than the critical density if the universe is flat. d. greater than the critical density if the universe is open. e. none of the above.arrow_forwardWhich of the following is most likely to yield evidence to support one of the models of the future of the universe? 1. Analysis of different types of radiation coming from the center of the Earth. 2. Analysis of asteroids in the solar system data collected from planetary missions. 3. Data collected from observing galaxies and clusters of galaxies of different ages. 4. Data collected from observing the arms of the Milky Way galaxy.arrow_forward
- In order to form a black hole, a star must be about how much more massive than our Sun? a. Fifty times as massive b. Ten times as massive c. Twice as massive d. Twenty times as massive e. It actually must be less massive than our Sunarrow_forwardIn the standard model, about when after the Big Bang did the universe become transparent to radiation? O a.10:35 , O b.10435 O C:3x 105 y O d.103 sarrow_forwardThe mass density of our universe is measured to be about 10-29 kg/m3. If an arbitrary point is chosen as the center, how large is the radius of a spherical surface centered at the point so that the mass enclosed in the surface will become a blackhole observed by someone outside the surface? A. 4.2 trillion light years B. 420 billion light years C. 42 billion light years D. 4.2 billion light years Is the answer D? Thanks!arrow_forward
- What is the approximate temperature of the universe that we currently observe? a. 0 K b. 2.7 K c. 273 K d. 3000 K e. 6000 Karrow_forward3. Consider the following two universes: Universe I: flat, matter-dominated with no cosmological constant or radiation, in which a(t) = (t/to)2/3. Universe II: flat, radiation-dominated with no cosmological constant or matter, in which a(t) = (t/to) ¹/². a. Which universe is expanding the fastest? b. For each case, use the Hubble law to show that to = 3/(2H₁) and to = 1/(2H₁) for universes I and II respectively. c. Based on the previous question, which universe would be the youngest assuming a given Ho value?arrow_forwardThe first evidence for the dark energy was that: a. the cosmic microwave background spectrum was a perfect black body. b. Einstein’s theory of gravity predicted that the Universe should collapse. c. Type Ia supernovae appeared dimmer than predicted by Hubble’s law. d. Cepheid variable stars showed that galaxies were farther away that thought. e. galaxies in clusters are moving too rapidly for the clusters to be bound.arrow_forward
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