A) 3000 K
B) 3 K
C) 300 K
D) The universe cannot be said to have a single temperature.
F) A) and C)
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A) the idea that the universe as we see it formed when two massive galaxies collided together
B) the idea that the galaxy formed from the supernova explosion of a massive star
C) the idea that all matter and energy in the universe began in an unimaginably dense state, and then space itself began expanding
E) A) and C)
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A) With the exception of very small variations, it appears essentially the same in all directions in which we look into space.
B) Its spectrum corresponds to a temperature of just under 3 degrees above absolute zero.
C) It is thought to be radiation that began its journey to our telescopes when the universe was about 380,000 years old.
D) It is the result of a mixture of radiation from many independent sources, such as stars and galaxies.
F) B) and D)
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A) The Big Bang happens simultaneously with the start of the expansion of the universe, then stars make the first elements heavier than helium, then the Sun forms.
B) The Big Bang happens simultaneously with the start of the expansion of the universe, then the Sun and stars make the first elements heavier than helium.
C) The Big Bang, then the expansion starts, then the Sun and stars make the first elements heavier than helium.
D) The Big Bang, then the expansion starts, then stars make the first elements heavier than helium, then the Sun forms.
F) A) and C)
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A) If "God did it" is the explanation for everything, then final exams in astronomy would be very simple (all answers would be the same!) , and science experiments would be very easy to explain, but we wouldn't learn much about the natural world.
B) Scientists are not allowed to believe in God.
C) Science cannot prove (or disprove) the existence of a superpowerful, supernatural deity.
D) The statement that "God did it" cannot be falsified by science, and therefore it is not a statement that science can test.
F) A) and C)
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A) Inflation would have caused random, microscopic quantum fluctuations to grow so large in size that they became the seeds of structure.
B) Inflation predicts that temperatures and densities should have become nearly equal throughout the universe.
C) Inflation predicts that gravity would have been very strong and thereby would have concentrated mass into seeds.
D) Inflation tells us that the universe should have a "flat" overall geometry, and this led to the flat disks of galaxies.
F) A) and D)
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A) The conditions in the very early universe must have been much like those found in stars today, so we learn about them by studying stars.
B) We work backward from current conditions to calculate what temperatures and densities must have been when the observable universe was much smaller in size.
C) We look all the way to the cosmological horizon, where we can see the actual conditions that prevailed all the way back to the first instant of the Big Bang.
D) We can only guess at the conditions, since we have no way to calculate or observe what they were.
F) A) and B)
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B) False
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A) essentially all of the chemical elements, except for those heavier than uranium
B) hydrogen, helium and trace amounts of lithium, beryllium, and boron
C) only helium
D) only hydrogen
E) roughly equal amounts of hydrogen, helium, lithium, beryllium, and boron
G) A) and B)
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A) Can we measure the position and momentum of an electron at the same time?
B) Why is the sky dark at night?
C) How many stars are in the universe?
D) What would it be like to ride on a beam of light?
F) All of the above
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B) False
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A) about 300 K
B) about 0.03 K
C) about 0.3 K
D) about 30 K
F) C) and D)
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A) Following this time, neither the strong nor electroweak forces were ever important in the universe again.
B) These forces are important only at temperatures below the freezing point of water-a temperature that the universe reached at an age of about at 10- 38 second.
C) Freezing out was a term coined by particle physicists who think that the Big Bang theory is really cool.
D) These two forces first became distinct at this time.
F) B) and C)
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A) The Big Bang began with the initiation of what we call inflation, which gradually slowed to the current expansion rate of the universe. Forces came to exist for a different reason, having to do with quantum fluctuations in the space- time continuum. Particles came to exist as a result of cracks made when forces froze. Once there were particles, gravity brought them together to make stars, and the stars then turned the particles into hydrogen, helium, and other elements.
B) An episode of what we call inflation initiated the event of the Big Bang. Once the Big Bang got underway, particles and forces began to appear one by one. The forces produced protons, which fused to make hydrogen and helium until the universe was about 380,000 years old. Then gravity began to act, turning the hydrogen and helium into galaxies.
C) Forces and various subatomic particles began to appear during the first second after the Big Bang. For reasons not understood, the particles were all made of ordinary matter and none were made of antimatter, thus explaining why we live in a universe made of matter. The particles underwent some fusion for the first 380,000 years after the Big Bang, at which time the first stars were born.
D) The universe began with the forces unified. During the first fraction of a second, the forces separated and there was a brief but important episode of inflation. Subatomic particles of both matter and antimatter then began to appear from the energy present in the universe. Most of the particles annihilated to make photons, but some became protons, neutrons, electrons, and neutrinos. The protons and neutrons underwent some fusion during the first five minutes, thereby determining the basic chemical composition of the universe.
F) None of the above
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A) We do not yet have a theory that links quantum mechanics and general relativity.
B) The Planck era was the time before the Big Bang, and we cannot describe what happened before that instant.
C) We do not know how hot or dense the universe was during that time.
D) We do not understand the properties of antimatter.
F) None of the above
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A) strong force, weak force, electric force, magnetic force
B) nuclear force, gravity, electric force, magnetic force
C) nuclear force, electromagnetic force, gravity, tidal force
D) strong force, weak force, electromagnetic force, gravity
F) A) and B)
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A) The universe was created by God.
B) The universe is about 14 billion years old.
C) The universe started out very hot.
D) The universe is about 2000 years old.
F) A) and B)
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A) 5 years
B) 0) 001 seconds
C) 10- 10 seconds
D) 5 seconds
E) 5 minutes
G) B) and D)
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A) small
B) filled with intense radiation
C) dense
D) hot
F) None of the above
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A) the photons released when electrons and protons first combined, forming the Cosmic Microwave Background Radiation
B) the sudden release of photons when particles and antiparticles annihilate each other
C) the expansion of universe starting with the instant after the Big Bang
D) a sudden expansion of the universe driven by the energy released when the strong and electroweak forces froze out from the GUT force
E) the rapid expansion of the universe, driven by white dwarf supernova, that we still observe today
G) All of the above
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