Study Guide Ch14

Chapter 14- Modern Cosmology

Study Guide

Answer is slashed threw its not the right one if in red it might be the answer.

The cosmological principle states that the universe is

I. expanding.

II. accelerating.

III. homogeneous.

IV. isotropic.

I and II

III and IV

I and III

II and IV

I, II, III and IV

Question 2

The assumption of homogeneity states that

the universe looks the same at all epochs.

the universe looks the same from all locations over sufficiently great distances.
the universe looks the same in all directions over sufficiently great distances.

all of the above

none of the above

Question 3

During the first moments of the big bang when elements could be created, nuclear fusion reactions made few heavy elements because

no stable nuclei exist with masses of 5 or 8 hydrogen masses.

Question 4

What observation has prompted astronomers to ponder the possible existence of dark energy?

Supernovae appear fainter than expected at large redshifts.

Question 5

The density of the universe is

equal to the critical density if the universe is flat.

Question 6

When a proton and an antiproton collide

they destroy each other and produce energy in the form of gamma rays.

Question 7

Why is the cosmic microwave background (CMB) so cold if the early universe was so hot?

The expansion of the universe has redshifted those photons to an effectively cooler temperature.

Question 8

Whether the universe is open, closed, or flat depends on the ____ of the universe.

density

Question 9

The cosmic background radiation comes from a time after the origin of the universe

when protons and neutrons were first formed.

when the big bang first began to expand.

during the inflationary period.

when gamma rays had enough energy to destroy nuclei.

when electrons began to recombine with nuclei to form atoms.

Question 10

The age of the universe can be estimated or constrained from

all of the above

Question 11

Which view of the universe states that the universe is eternal and unchanging?

static

Question 12

The Hubble time is

an estimate of the age of the universe based on the Hubble constant.

Question 13

What is the fate of an open universe?

Expansion forever

Question 14

In the late 1990s, it was discovered from distances of ______ in distant galaxies that the expansion of the universe is ___________.

supernovae; accelerating

Question 15

If the universe is closed and finite, then

the universe will expand forever.

the universe has a center.

the universe has an edge.

none of the above

Question 16

Where did the cosmic microwave background (CMB) come from?

Photons released when electrons and nuclei combined for the first time

Question 17

Space-time will be flat if

the universe is expanding.

the universe is accelerating.

the average density of the universe is equal to the critical density.

the universe is finite.

the universe is homogeneous and isotropic.

Question 18

The assumption of isotropy states that

the universe looks the same in all directions over sufficiently great distances.

Question 19

Current evidence suggests that the universe is

flat, infinite, and accelerating in its expansion.

Question 20

The best determination of the Hubble constant using Cepheid variables found in distant galaxies by the Hubble telescope suggests

that the Hubble constant is about 0.07  km/sec/Mpc.

that the Hubble constant is about 7 km/sec/Mpc.

that the Hubble constant is about 70  km/sec/Mpc.

that the Hubble constant is about 700 km/sec/Mpc.