Deck 27: The Early Universe: Toward the Beginning of Time

Question 1

Deuterium and helium could be made only during the nuclear epoch.

Answer 1

False

Question 2

String theories, like GUTs, explain how gravity was combined with the other fundamentalforces in the very early universe.

Answer 2

False

Question 3

Deuterium was made only in primordial nucleosynthesis, since stars destroy it.

Answer 3

True

Question 4

When an electron is formed from a gamma-ray collision, a positron is also made.

Question 5

The density of the cosmos at the end of the lepton epoch was comparable to iron, about tentimes denser than water.

Question 6

Not taking dark energy into account, we seem to live now in a matter dominated universe,since the observed matter density exceeds the observed energy density.

Question 7

The collision of two gamma rays can result in a single particle.

Question 8

At decoupling, the electrons and protons were made from neutron decay.

Question 9

The protons, neutrons, and electrons of our atoms were made in the quark epoch.

Question 10

In pair production, the heaviest particles are formed in reactions that have the highesttemperatures.

Question 11

Decoupling refers to interactions between matter and antimatter at the end of the RadiationEra.

Question 12

Including all energy and mass, both dark and traditional, we seem to live now in a matterdominated universe, since the observed matter density exceeds the observed energy density.

Question 13

Quarks are made up of subatomic particles, such as protons and electrons.

Question 14

In GUTs, the electromagnetic force and weak nuclear force were the first to separate; thencame gravity.

Question 15

Primordial nucleosynthesis refers to the Big Bang making all elements up to iron.

Question 16

In GUTs, gravity was the first force to take on a separate identity at the Planck Time.

Question 17

The horizon problem relates to the isotropy of the microwave background radiation.

Question 18

The period before the separation of the gravitational force is the Planck Epoch.

Question 19

Before the Planck time of $10 ^{- 43}$ seconds, the Big Bang must be treated as a singularity, witheven general relativity yielding no information about it.

Question 20

Pair production is how a proton and electron are formed together from two photons, withneutrinos also given off.

Question 21

In pair production in the Big Bang, which statement is FALSE?

A)The heaviest particles and their antiparticles formed first, from collisions of the highestenergy gamma rays.
B)Matter is frozen energy, according to Einstein's $\mathrm { E } = \mathrm { mc } 2$
C)Every electron should have a proton formed at the same time with it.
D)Even neutrons have their antineutrons, although both lack any charge.
E)In addition to familiar neutrons and protons, many other exotic particle and antiparticle pairsformed, but decayed back to radiation.

Question 22

How hot was the universe at time zero?

A)2.73 K
B)5, 800 K
C)16, 000 K
D) $1032 \mathrm {~K}$
E)We have no theory capable to addressing this question.

Question 23

The majority of dark matter is probably not protons and neutrons.

Question 24

The crossover point from radiation to matter domination occurred:

A)when the strong force separated from the other two forces.
B)with the emission of the cosmic background radiation.
C)about 50,000 years after the Big Bang, at a temperature of about $16,000 \mathrm {~K}.$
D)with the creation of neutrons and protons, at about $10^{13} \mathrm {~K}$
E)with the creation of electrons and positrons at about $6 \times 10 ^ { 9 } \mathrm {~K}$

Question 25

In the process of pair production, which of the following is a possible product pair?

A)electron-neutron
B)proton-neutron
C)electron-positron
D)proton-positron
E)electron-proton

Question 26

Because of their mass, the threshold temperature for electrons is:

A)higher than that of neutrons.
B)lower than that of protons.
C)higher than that of protons.
D)lower than that of hydrogen.
E)higher than that of hydrogen.

Question 27

The universe expanded by a factor of $10^{50}$ during inflation, when the strong force separatedfrom the electromagnetic and weak nuclear forces.

Question 28

Currently, most of the mass of the matter of the universe is believed to consist of:

A)baryonic matter, made up of protons and neutrons.
B)tachyonic matter, travelling only faster than the speed of light.
C)dark matter not made of protons and neutrons.
D)dark energy.
E)tiny but very numerous black holes.

Question 29

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.

Question 30

Sound waves in the early universe traveled faster than half of the speed of light.

Question 31

Before about 50,000 years after the Big Bang, the universe was:

A)radiation dominated.
B)quark dominated.
C)lepton dominated.
D)matter dominated.
E)dark energy dominated.

Question 32

The critical temperature above which pair production can occur is called the:

A)Chandrasekhar Limit.
B)Cosmological Constant.
C)fusion temperature.
D)threshold temperature.
E)event horizon.

Question 33

Physicists have detected hot dark matter particles in terrestrial laboratories, but it is muchharder to observe than cold dark matter.

Question 34

Before about 4 billion years ago the universe was:

A)radiation dominated.
B)quark dominated.
C)lepton dominated.
D)matter dominated.
E)dark energy dominated.

Question 35

At this time, the universe is:

A)radiation dominated.
B)quark dominated.
C)lepton dominated.
D)matter dominated.
E)dark energy dominated.

Question 36

The flatness problem is the fact that the observed density of matter is unexpectedly differentfrom the critical density predicted by the inflationary epoch.

Question 37

How does the energy of the cosmic microwave background compare to the energy radiated byall 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.

Question 38

Both protons and neutrons (and their anti-particles)froze out:

A)after $10^{ - 43}$ seconds, at the Planck Era.
B)at $1032 \mathrm {~K}$ at the end of the Inflationary Era.
C)at $1013 \mathrm {~K} \text {, }$ , bout .0001 seconds after the Big Bang.
D)after about a minute of expansion.
E)about 50,000 years after the Big Bang.

Question 39

Pair production can occur if:

A)the energy of two photons is greater than the combined mass-energy of a particle-antiparticlepair.
B)only virtual particles are produced.
C)photons are at the event horizon of a black hole.
D)one particle is struck by a sufficiently high energy photon that a pair of electrons is formed.
E)the particle and antiparticle have opposite spins.

Question 40

When new particle pairs are being created as fast as they annihilate, it is:

A)hydrostatic equilibrium.
B)thermal equilibrium.
C)the threshold equilibrium.
D)the cosmological constant.
E)the critical density.

Question 41

The period from about 100 seconds up to 15 minutes after the Big Bang is the:

A)Radiation Era.
B)Lepton Epoch.
C)Nuclear Epoch.
D)Decoupling Epoch.
E)Matter Era.

Question 42

Collectively, electrons, muons, and neutrinos are called:

A)hadrons.
B)baryons.
C)photons.
D)leptons.
E)pions.

Question 43

Of the normal elements around us, the Big Bang produced:

A)none, only energy.
B)only hydrogen.
C)hydrogen and helium.
D)all elements up to iron.
E)all elements in much their present proportions.

Question 44

Which of these orderings of the epochs is correct?

A)nuclear, quark, galactic
B)atomic, nuclear, stellar
C)Planck, lepton, quark
D)nuclear, lepton, quark
E)galactic, stellar, atomic

Question 45

The stellar epoch, which we are still in today, began:

A)with the end of the quark epoch, when neutrons and protons fused into deuterium.
B)with the end of the lepton epoch, when neutrinos were formed and escaped from matter.
C)with the liberation of the dark energy.
D)about 100 million years after the Big Bang, with the making of galaxies.
E)about three billion years after the Big Bang, with Population I stars forming.

Question 46

The period from about one to 100 seconds after the Big Bang is called the:

A)pair-production era.
B)atomic epoch.
C)nuclear epoch.
D)quark epoch.
E)lepton epoch.

Question 47

Scientists are able to use the theories of physics to describe the conditions of the universeback to:

A)the moment of the Big Bang.
B)the end of the Planck Epoch.
C)the beginning of GUT.
D)the end of the Radiation Era.
E)the Recombination Epoch.

Question 48

The nuclear epoch occurred during the formation of:

A)only protons and neutrons.
B)dark energy.
C)deuterium and helium.
D)all elements up to iron.
E)all known elements.

Question 49

During the nuclear epoch, the temperatures were:

A)higher than $10^{32} \mathrm {~K} .$
B)about a trillion degrees.
C)comparable to the temperatures inside giant stars today.
D)less than 10 million K.
E)between 3,000 and 16,000 K.

Question 50

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 gravitational, strong and weak nuclear, and electromagnetic forces.
E)only in effect at low energies.

Question 51

Gravity becomes separate from the other forces at the:

A)decoupling Event, about a million years after the Big Bang.
B)end of the Planck Era, about $10 - 43$ seconds after the Big Bang.
C)end of the Inflationary Epoch, about $10 - 32$ seconds into creation.
D)beginning of particle production, about .0001 seconds into the universe.
E)end of electron production, about a minute after creation.

Question 52

What would help scientists probe the period from zero time to $10 - 43$ second?

A)discovery of a white hole, with matter and energy flowing out
B)more sophisticated gravity wave detectors
C)a theory incorporating the force of gravity into existing GUTs
D)a better understanding of the nature of dark energy
E)more detailed observations of the cosmic microwave background

Question 53

What key event took place during the atomic epoch?

A)The universe expanded and cooled enough to allow the first particles to appear.
B)The universe expanded and cooled enough for electrons to orbit protons.
C)The neutrinos were created.
D)Atoms in the universe collected to form stars and galaxies.
E)The universe underwent a brief period of rapid expansion.

Question 54

The quark epoch is when ________ was/were created.

A)all known matter
B)everything in normal atoms
C)only dark energy
D)protons and neutrons that still survive
E)the rapid inflation of the cosmos

Question 55

Which of these orderings of the epochs is correct?

A)nuclear, stellar, galactic
B)quark, lepton, atomic
C)Planck, lepton, quark
D)nuclear, lepton, quark
E)Planck, stellar, galactic

Question 56

How do astronomers define the "superforce"?

A)a force connecting electromagnetism with the strong and the weak nuclear forces
B)the GUT, with all five forces combined
C)the GUT, but with no dark energy added in
D)a force connecting gravity and the electroweak force
E)a force including only dark energy and gravity

Question 57

At what point do the weak nuclear and electromagnetic forces split?

A)never, they are still united
B)at $10^{12} \mathrm {~K} \text {, }$ when pair production starts for neutrons and protons
C)at $10 ^{- 43}$ seconds, when all four forces separate as the Planck Era ends
D)at about four seconds, when at millions of degrees hydrogen forms helium
E)after about $10 ^ { - 10 }$ seconds, when the temperature drops below $10 ^ { - 15 } \mathrm {~K}$

Question 58

After the atomic epoch, and before the current stellar epoch, came:

A)the black hole epoch, when black holes were common.
B)the end of the lepton epoch, when neutrinos were formed and escaped from matter.
C)the liberation of the dark energy.
D)the galactic epoch, when the main events were galaxy construction.
E)about three billion years after the Big Bang, with Population I stars forming.

Question 59

Which of these substances must be primordial?

A)helium
B)lithium
C)deuterium
D)beryllium
E)tritium

Question 60

At the end of the first fifteen minutes, the mass ratio of H/He created was about:

A)50/50.
B)75/25.
C)27/73.
D)90/10.
E)1/4.

Question 61

The critical temperature for nucleosynthesis to begin was the:

A)triple alpha reaction at 100 million K.
B)deuterium bottleneck at about 900 million K.
C)proton-proton cycle at 10 million K.
D)iron production at 10 billion K.
E)formation of lithium at 50 million K.

Question 62

Most of the deuterium that 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.

Question 63

The "flatness" problem arises because the curvature of space seems remarkably close to:

A)zero curvature, favoring a spherical cosmos.
B)exactly one.
C).5, suggesting we are split between open and closed universes.
D)2.73 K, in spite of the eddies and turbulence that led to galaxy formation.
E)infinity, suggesting an open universe is the only possible cosmology.

Question 64

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.

Question 65

Which of these seems the best present answer to the horizon and flatness problems?

A)The superforce rules creation.
B)Dark Energy speeds the universe on out to infinity.
C)symmetry in creation of particles and antiparticles
D)the inflationary epoch
E)the GUT theory

Question 66

Which of these did NOT occur at decoupling?

A)The cosmic microwave radiation was released from matter.
B)Neutral atoms were formed.
C)Matter dominated radiation.
D)Electrons began to orbit protons.
E)The universe became transparent.

Question 67

The redshift of the universe at decoupling was about:

A)Z = 1,000,000.
B)Z = 400,000.
C)Z = 1,100.
D)Z = 10.
E)Z = 4.

Question 68

Observed temperature fluctuations in the Cosmic Microwave Background Radiation are:

A)millions of kelvins.
B)hundreds of kelvins.
C)a few kelvins.
D)tens of millionths of a kelvin.
E)immeasurably small.

Question 69

The one theory of the early universe before the Recombination Epoch and after the PlanckEpoch that was developed to resolve a conflict between observation and theory is:

A)the Grand Unified Theory.
B)the theory of inflation.
C)the theory of nucleosynthesis.
D)the theory of recombination.
E)the quantum quark theory.

Question 70

Which of these could be considered as "hot dark matter"?

A)deuterium
B)weakly interacting magnetic particles (WIMPS)
C)neutrinos
D)dust close to H II regions
E)dark energy

Question 71

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.

Question 72

Oscillations in the early universe are most similar to:

A)water waves.
B)sound waves.
C)light waves.
D)seismic waves.
E)oscillations of stars in the instability strip of the H-R diagram.

Question 73

About how hot was the Big Bang when matter and energy "decoupled"?

A)900 million K
B)15 million K
C)3,000 K
D)300 K
E)2.73 K

Question 74

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.

Question 75

What did the cosmic microwave background tell cosmologists about the early universe?

A)Nothing; it is a product of the black hole in the center of our own Galaxy.
B)the horizon problem, in that the microwave background is almost too isotropic
C)the discovery of dark energy and its role in accelerating the universe
D)the discovery of relativistic redshifts and the Big Bang
E)The dark matter in the universe is mostly baryonic in nature, for a closed Big Bang.

Question 76

Cold-dark-matter models predict:

A)large-scale filaments containing both normal matter and dark matter.
B)no structure on a smaller scale than superclusters.
C)the universe is less than 10 billion years old.
D)dense regions of the early universe that led to galaxies formed after decoupling.
E)that dark matter is the largest component of the universe's density.

Question 77

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.

Question 78

The scarcity of what isotope is a critical test of the density of the present cosmos?

A)carbon 14
B)deuterium
C)helium 3
D)helium 4
E)lithium 5

Question 79

There is observational evidence that supports the theoretical conditions of the universe. Thefarthest back in the history of the universe this evidence goes is:

A)the moment of the Big Bang.
B)the end of the Planck epoch.
C)the beginning of GUT.
D)the end of the Radiation Era.
E)the Recombination Epoch.

Question 80

The Big Bang formed:

A)only hydrogen.
B)only helium.
C)hydrogen and helium, but nothing else.
D)all elements up to iron.
E)all elements found in nature now.