29.1.0 The Age of the Universe

3. When we determine the age of the universe using the Hubble Time, what important simplifying assumption goes into our calculations? a. that the expansion of the universe has been happening at the same rate - neither speeding up or slowing down b. that all the galaxies are moving away from us at exactly the same speed, no matter how far away they are c. that the cosmological principle doesn't hold: the universe is not isotropic and homogeneous d. that we have accounted correctly for the effects of dark energy e. that the universe is actually contracting instead of expanding

a. that the expansion of the universe has been happening at the same rate - neither speeding up or slowing down

2. Why did Einstein introduce the cosmological constant into the equations of his General Theory of Relativity when describing the universe? a. Einstein did not realize that black holes would exist at the centers of galaxies and pull everything into them b. Einstein's equations required the universe to expand or contract; he could not imagine or accept it doing either one, so he put a factor in to stop it from moving c. Einstein talked to Hubble and learned about Hubble's observations of the expanding universe, which made him so uncomfortable that he decided to change his equations d. Einstein had a hunch that the universe was accelerating (speeding up its expansion) back in 1918 and so introduced the constant into his equations to describe that e. Einstein liked cups of tea in the afternoon, and his constant was a comment on that habit

b. Einstein's equations required the universe to expand or contract; he could not imagine or accept it doing either one, so he put a factor in to stop it from moving

8. If we include the effects of deceleration in our calculations of the age of the universe, the age we get is: a. greater than the Hubble time b. less than the Hubble time c. equal to the Hubble time d. either greater or less depending on the amount of deceleration e. you can't fool me; this question cannot be answered without knowing the exact value of the Hubble constant.

b. less than the Hubble time

1. Which of the following is the Earth not located in? a. the solar system b. the universe c. globular cluster M-13 d. the Milky Way Galaxy e. the Earth is located in all of the above

c. globular cluster M-13

5. When do astronomers now think that the "dark energy" began to accelerate the expansion of the universe? a. right after the Big Bang (after the first three minutes or so) b. a few million years after the Big Bang c. several billion years after the Big Bang d. about ten million years ago e. when the city of Bayonne, New Jersey was founded

c. several billion years after the Big Bang

7. The reciprocal of the Hubble constant (1/H) is a rough measure of the: a. the period of a typical Cepheid variable b. the distance to the last galaxies that formed c. the age of the universe d. the luminosity of a type I supernova explosion e. the cost of building a telescope in space

c. the age of the universe

4. The standard bulbs (standard candles) that made it possible for astronomers to discover the acceleration in the expansion of the universe were a. globular clusters b. Cepheid variable stars c. the brightest irregular galaxy in a rich cluster d. Type Ia supernovae e. the size of a galaxy dark matter halo

d. Type Ia supernovae

6. Factoring in everything we currently know about the history of the universe, our best estimate for the age of the universe is a. 4.6 billion years b. about 100 billion years c. roughly 2 million years d. about 13.8 billion years e. the age of the universe is infinite; there was no beginning

d. about 13.8 billion years