Deck 18: Modern Cosmology

Question 1

In the early universe, the electromagnetic and strong nuclear forces were joined together to make the electrostrong force.

Answer 1

False

Question 2

The decoupling of the strong force from the electroweak force provided energy for a rapid inflation of the Universe.

Answer 2

True

Question 3

The Universe has____.

A) an edge, does not have a center, and is finite
B) no edge, does not have a center, and is finite
C) an edge, has a center, and is finite
D) an edge, has a center, and is infinite
E) no edge, does not have a center, and is infinite

Answer 3

no edge, does not have a center, and is infinite

Question 4

The big bang happened everywhere in the Universe at the same time.

Question 5

Dark energy accounts for about 70% of the critical density of the Universe.

Question 6

Olber's paradox is explained by the fact that the Universe is neither static nor infinite in age.

Question 7

When matter and antimatter particles combine, the two particles annihilate each other and convert their mass into energy in the form of two gamma rays.

Question 8

Tiny amounts of lithium and beryllium were formed in the big bang.

Question 9

The proper interpretation of the Hubble law (which relates the redshift of a galaxy to its distance) is that as time goes on, galaxies are____.

A) staying relatively still in space while the space between the galaxies contracts
B) moving away from a common center in space that is neither expanding nor contracting
C) staying relatively still in space while the space between the galaxies expands
D) moving away from a common center while the space between the galaxies expands
E) moving toward a common center in space that is neither expanding nor contracting

Question 10

The Hubble time is____.

A) an estimate of the age of the Universe
B) the time needed for a galaxy to travel 1 Mpc
C) not connected to Hubble law of galactic redshifts
D) the time for light to cross the Universe
E) the time needed for galaxies to form

Question 11

The "big bang" was an explosion of material that created galaxies flying away from the center of the explosion.

Question 12

The expansion of the Universe is accelerating.

Question 13

All dark matter in our Universe falls into the category of "hot dark matter".

Question 14

Normal matter is baryonic.

Question 15

The cosmological principle states that any observer in any galaxy sees the same general properties for the Universe.

Question 16

Olber's paradox states that the ____.

A) Universe must have a center, but not an edge
B) sky should be as bright as the surface of a star in all directions
C) Universe should have an edge, but not a center
D) Earth should be at the farthest point in the Universe from the big bang.
E) Universe is not infinite, but cannot have an edge or center

Question 17

The cosmological redshifts of galaxies are Doppler shifts.

Question 18

After nuclear reactions in the big bang had ended, about 25% of the mass of the Universe was in the form of helium nuclei.

Question 19

The Universe is isotropic, but not homogenous.

Question 20

Cosmologists cannot begin their history of the big bang at a time of exactly zero because it cannot be explained by current physics.

Question 21

The observed distribution of matter in the Universe is best understood as being caused by ____.

A) clumping of dark matter in the early Universe causing clumping of normal matter
B) clumping of normal matter in the early Universe causing clumping of dark matter
C) simultaneous clumping of normal and dark matter
D) large variations in the intensity of the cosmic microwave background
E) homogenous expansion of normal and dark matter

Question 22

The proper interpretation of a what a galaxy's redshift measures is ____.

A) its motion in space toward the observer
B) its motion in space away from the big bang
C) the stretching of space between the galaxy and the observer
D) the contraction of space between the galaxy and the observer
E) the stretching of space between the galaxy and the big bang

Question 23

In the very first phase after the big bang, when the Universe was about a microsecond old, space was filled with____.

A) high-energy photons
B) protons and antiprotons
C) protons, neutrons, electrons, and positrons (anti-electrons)
D) electrons, and positrons (anti-electrons)
E) protons, neutrons, electrons

Question 24

Figure 18-12 (for the following questions) The re-ionization of the Universe occurredclosest to ____ degrees Kelvin.

A) tens of thousands of
B) thousands of
C) hundreds of
D) tens of
E) less than ten

Question 25

Einstein's mass-energy equivalence () is important to the first phases of the big bang in explaining how____.

A) gamma ray photons create matter and antimatter
B) stable protons and neutrons can exist below a certain temperature
C) antimatter can exist
D) matter became more prevalent than antimatter
E) the Universe expanded rapidly

Question 26

Figure 18-12 (for the following questions) The Universe had a temperature of a few hundred million degrees K at approximately ____ after the big bang.

A) one second
B) one minute
C) one hour
D) one day
E) one year

Question 27

The microwave emission detected by Arno Penzias and Robert Wilson fits a blackbody spectrum with a temperature of about ____.

A) 0 K
B) 273 K
C) 27 K
D) 7.2 K
E) 2.7 K

Question 28

The cosmic microwave background radiation was emitted during a time when ____ was the important process in the Universe.

A) recombination
B) ionization
C) fusion
D) antiproton production
E) positron production

Question 29

The main criterion for deciding between Universe geometries is ____.

A) density
B) mass
C) temperature
D) age
E) inflation

Question 30

Penzias and Wilson detected microwave radiation because the big bang created ____.

A) shorter wavelength energy that has been redshifted by expansion
B) longer wavelength energy that has been redshifted by expansion
C) microwave radiation that has not been affected by expansion
D) shorter wavelength energy that has been blueshifted by expansion
E) longer wavelength energy that has been blueshifted by expansion

Question 31

Which statement about the behavior of Universe geometries is correct?

A) Closed and open universes expand forever.
B) Closed universes expand and then contract.
C) Only flat universes expand forever.
D) Flat and open universes expand and then contract.
E) Only flat universes expand and then contract.

Question 32

Clusters of galaxies are distributed in space ____.

A) homogenously
B) isotropically
C) in long, narrow filaments surrounding empty voids
D) statically
E) in bubbles surrounded by empty walls

Question 33

Figure 18-12 (for the following questions) One year after the big bang, the temperature of the Universe was approximately____ degrees Kelvin.

A)
B)
C)
D)
E)

Question 34

Arno Penzias and Robert Wilson are famous for____.

A) creating the first microwave telescope
B) finding the direction of the center of the Universe
C) detecting energy released in the splitting of the electroweak force
D) detecting the large redshift background radiation from the big bang
E) measuring the temperature of the big bang

Question 35

During one phase of the big bang, gamma ray photons were creating electrons and positrons (anti-electrons). At this time, the Universe also contained ____.

A) protons and antiprotons
B) protons and neutrons
C) neutrons only
D) no other matter or antimatter
E) neutral atoms

Question 36

The big bang only created hydrogen and helium (with miniscule amounts of lithium) because____.

A) gamma ray photons disrupt large nuclei more easily
B) antimatter is attracted to large nuclei, leaving only light nuclei
C) heavier elements can only be formed through fusion
D) elements with an atomic weight of 5 or 8 are unstable
E) temperatures were high enough to fuse hydrogen, but not helium

Question 37

Ordinary matter makes up approximately ____percent of the critical density of the Universe.

A) 0.1
B) 1
C) 4.5
D) 10
E) 50

Question 38

Hot gas created during the big bang should be detectable becausethe ____.

A) gas has traveled with galaxies as they formed and is spread through the Universe of the present day
B) big bang occurred everywhere at once, and should be visible in any direction at long look-back times
C) big bang occurred in a certain location, and the radiation from the gas is concentrated there
D) gas has travelled to the edges of the Universe and will be visible at negative redshifts
E) radiation emitted by the gas has travelled at the same speed as the expanding Universe and is visible all around us

Question 39

Figure 18-12 (for the following questions) The change from a radiation-dominated to a matter-dominated Universe occurred at a temperature closest to ____ of degrees Kelvin.

A) millions
B) hundreds of thousands
C) tens of thousands
D) thousands
E) hundreds

Question 40

Modern observations have shown that the geometry of the Universe is ____.

A) flat, and the Universe must be infinite
B) flat, and the Universe must not be infinite
C) open, and the Universe must be infinite
D) closed, and the Universe must be infinite
E) closed, and the Universe must not be infinite

Question 41

The four fundamental forces in the Universe are the ___ forces.

A) strong, weak, electrical, and magnetic
B) electromagnetic, gravitational, nuclear, and weak
C) electromagnetic, gravitational, strong, and weak
D) magnetic, electroweak, gravitational, and strong
E) electromagnetic, unified, strong, and weak

Question 42

If the dark energy is described by the cosmological constant, then the _____ Universe is ____.

A) open; accelerating and will not expand forever
B) flat; decelerating and will expand forever
C) closed; accelerating and will expand forever
D) open;, decelerating and will expand forever
E) flat; accelerating and will expand forever

Question 43

The gas created by the big bang was so hot that it was completely _______________ until the Universe was no longer radiation-dominated.

Question 44

The heaviest element created in the big bang, in tiny amounts, is _______________.

Question 45

Dark matter must be ____.

A) baryonic
B) non-baryonic
C) neutral
D) WIMPs
E) isochronic

Question 46

The radiation detected by Penzias and Wilson is sometime referred to as CMBR, which stands for   _______________ radiation.

Question 47

The cosmic microwave background radiation comes from the time when neutral hydrogen atoms formed in the process of _______________.

Question 48

The fact that the properties of the Universe are close to the dividing line between open and closed Universes refers to the _______________ problem.

Question 49

The evolution of the distribution of dark and normal matter were____.

A) both controlled by large differences in the cosmic microwave background radiation
B) different because dark matter does not interact with electromagnetic forces
C) different because dark matter does not interact with gravitational forces
D) different because dark matter does not interact with weak nuclear forces
E) different because dark matter does not interact with strong nuclear forces

Question 50

Scientists who study the Universe as a whole are called _______________.

Question 51

The Universe is _______________ because it looks the same in any direction you observe it.

Question 52

The Hubble time only describes a Universe that is ____.

A) flat
B) totally open
C) totally closed
D) partially open
E) partially closed

Question 53

Dark matter ____.

A) is homogenously distributed through the Universe
B) began clumping due to tiny variations in density at the moment of the big bang
C) began clumping due to large variations in the distribution of matter and antimatter
D) is isotropically distributed through the Universe
E) began clumping due to the variations in the distribution of baryonic matter

Question 54

The fact that the cosmic microwave background radiation has almost exactly the same temperature in every direction is referred to as the _______________ problem.

Question 55

The acceleration of the Universe depends on the effect of ____.

A) baryonic matter being greater than the effects of dark matter and dark energy
B) baryonic matter and dark energy being greater than the effect of dark matter.
C) dark matter and dark energy being greater than the effect of baryonic matter.
D) baryonic matter and dark matter being greater than the effect of dark energy.
E) dark matter being greater than the effect of dark energy.

Question 56

The separation of the strong force and the electroweak force ____.

A) provided the energy for a rapid inflation of the early Universe
B) created the cosmic microwave background radiation
C) balanced the critical density of the Universe to solve the flatness problem
D) created dark matter
E) created dark energy

Question 57

The flatness problem and the horizon problem can be explained by ____.

A) dark energy
B) the inflationary universe hypothesis
C) grand unified theories
D) the electroweak force
E) non-baryonic matter

Question 58

Dark energy is the term used to describe ____.

A) the pressure inflating "voids" in the distribution of galaxies
B) radiation from antimatter and non-baryonic matter
C) a component of the cosmic microwave background radiation
D) an effect that works with gravity to decelerate the expansion of the Universe
E) an effect that works against gravity to accelerate the expansion of the Universe

Question 59

The expansion of the Universe ____.

A) was faster in the early Universe when galaxies were close to each other, and has decelerated thereafter
B) was slower in the early Universe when galaxies were close to each other, and has accelerated thereafter
C) has been constant throughout the lifetime of the Universe
D) steadily accelerated from the big bang to the present day
E) steadily decelerated from the big bang to the present day

Question 60

Einstein's theory of mass-energy equivalence shows that high-energy photons can convert into matter and _______________.

Question 61

Why do astronomers conclude that the Universe is filled with dark energy? Discuss two of the primary reasons.

Question 62

Briefly describe the steps in the big bang that provided the protons, neutrons, and electrons necessary for nucleosynthesis - the building of complex atoms.

Question 63

The recombination era of the big bang was very important in several ways. Explain what happened during this time and what observable effects of the era existed.

Question 64

What three main observed phenomena are the strongest support for the "big bang" theory?

Question 65

What are the four fundamental forces in the Universe and how did they affect the first steps of the big bang and the inflation of the Universe?

Question 66

The _______________ universe hypothesis predicts a sudden, temporary episode of rapid, enormous expansion of the early Universe.

Question 67

How did dark matter behave differently from normal matter during the early stages of the big bang, and how is this important for the formation of stars and galaxies?

Question 68

When an astronomer measures the redshift to a distant galaxy, exactly what physical process is being measured?

Question 69

How is antimatter created?

Question 70

Why did the big bang only create hydrogen, helium, and trace amounts of lithium?

Question 71

The density of the Universe comes from baryonic matter, non-baryonic dark matter, and dark energy. What percentage of the density of the Universe do each of the three represent?