A) both the Big Bang and inflation
B) only the Big Bang,but not inflation
C) not the Big Bang,but inflation
D) neither the Big Bang nor inflation
F) B) and C)
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A) What would it be like to ride on a beam of light?
B) Can we measure the position and momentum of an electron at the same time?
C) How does the Sun produce energy?
D) Why is the sky dark at night?
E) How many stars are in the universe?
G) A) and D)
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A) Gravity was an extremely weak force at this period in time.
B) Large amounts of matter and antimatter annihilated at this time.
C) There wasn't enough matter present to slow down the expansion at that time.
D) The universe was too small and needed to grow quickly.
E) An enormous amount of energy was released when the strong force froze out from the GUT force.
G) C) and D)
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A) darkness of the night sky
B) recession speeds of far away galaxies relative to close ones
C) observed helium abundance in the universe
D) relative motions of galaxies in the Local Group
F) A) and C)
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A) You are in the center of a star very much like our Sun.
B) You are in the early universe during the era of nucleosynthesis.
C) You are inside a nuclear power plant on Earth.
D) You are in the center of a massive star near the end of its life.
E) You are in the center of a star much smaller than the Sun.
G) A) and E)
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A) Our universe is flat.
B) Prior to the Planck time,our universe sprouted from another universe.
C) The universe is 14 billion years old.
D) The expansion of the universe is now accelerating.
F) None of the above
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A) These two forces first became distinct at this time.
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) Following this time,neither the strong nor electroweak forces were ever important in the universe again.
F) A) and C)
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The era of nucleosynthesis is important ...View Answer
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A) You are plunging into the Sun.
B) You are crossing the event horizon of a black hole.
C) You are being consumed by a "crack" in the universe caused by inflation.
D) You are near the center of a star that has just developed an iron core,leading to a supernova.
E) You are in a medieval torture chamber somewhere in western Europe.
G) A) and E)
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A) It is the time at which inflation is thought to have occurred.
B) Before it,conditions were so extreme that our current understanding of physics is insufficient to predict what might have occurred.
C) It is the time when the cosmic microwave background was released.
D) It is the amount of time required for two protons to fuse to make deuterium.
F) A) and D)
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A) the total amount of mass in the universe.
B) the density of ordinary (baryonic) matter in the universe.
C) the acceleration of the universe.
D) the current age of the universe.
F) None of the above
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A) The background radiation came from the heat of the universe,with a peak corresponding to the temperature of the universe.
B) The spectrum of pure hydrogen is a perfect thermal radiation spectrum.
C) The spectrum of 75 percent hydrogen and 25 percent helium is a perfect thermal radiation spectrum.
D) The light from all the stars and gas in the sky averaged over the entire universe is a perfect thermal radiation spectrum.
E) It doesn't predict that the cosmic background radiation should have a perfect thermal radiation spectrum.
G) B) and D)
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A) 1 million years
B) 300,000 years
C) 300 years
D) 3 minutes
E) 10⁻¹⁰ second
G) B) and D)
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The two key pieces of evidence that supp...View Answer
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B) False
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A) 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 three minutes,thereby determining the basic chemical composition of the universe.
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 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.
F) A) and C)
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B) False
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B) False
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A) The overall structure of the universe is very uniform,but the universe must have contained some regions of higher density in order for galaxies to form.
B) The temperature of the universe can be found by taking an average over the entire sky,but individual stars will create peaks in the spectrum over small angles.
C) Dark matter consisting of WIMPs greatly smooths out the spectrum,but the small patches of "light" matter create peaks in the spectrum.
D) The overall structure of the universe is very uniform,but the synthesis of different elements produces varying signatures within the background spectrum.
E) The overall structure of the universe is very uniform,but intervening gas between us and the era of nuclei absorbs wavelengths depending on the composition and redshift of the gas.
G) B) and D)
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A) the cosmic background radiation and the high helium content of the universe
B) the cosmic background radiation and the expansion of the universe
C) the cosmic background radiation and the near-critical density of the universe
D) the predominance of matter over antimatter and the near-critical density of the universe
E) the predominance of matter over antimatter and the large scale structure of galaxies
G) All of the above
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