Exam 17: The Beginning of Time

A) Critical
B) Accelerating
C) Recollapsing
D) Coasting

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A) The combined mass of the two particles is completely transformed into energy (photons) .
B) They can form a complete atom.
C) They fuse to make a heavier particle.
D) The question makes no sense, since antimatter does not really exist.

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A) a galaxy with 30% helium abundance.
B) the temperature of the universe is only 2.73 K.
C) a galaxy with 10% helium abundance.
D) a galaxy moving toward us.
E) two galaxies, at the same distance, moving away with slightly different speeds.

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Structure problem: The fact that there a...

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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 gravity would have been very strong and thereby would have concentrated mass into seeds.
C) Inflation tells us that the universe should have a "flat" overall geometry, and this led to the flat disks of galaxies.
D) Inflation predicts that temperatures and densities should have become nearly equal throughout the universe.

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A) unify the strong force with the electromagnetic and weak forces
B) unify gravity with the strong and weak forces
C) unify the electromagnetic and weak forces
D) unify all four forces together

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A) The basic chemical composition of the universe had been determined.
B) The proportions of dark matter and luminous matter had been determined.
C) It marks the time at which the first stars formed.
D) It marks the time at which the expansion of the universe had settled down to its current rate.

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A) the cosmic background radiation and the 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 the universe

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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 star much smaller than the Sun.
E) You are in the center of a massive star near the end of its life.

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A) All the free particles had combined to form the nuclei of atoms.
B) The universe had expanded and cooled enough for stable, neutral atoms to form.
C) Atomic nuclei were finally able to escape the plasma of the early universe.
D) Photons were finally able to escape the plasma of the early universe and were no longer available to produce hydrogen and helium nuclei.
E) The nucleosynthesis era that produced the nuclei heavier than helium ended.

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A) stellar nucleosynthesis only.
B) the Big Bang only.
C) mostly from stellar nucleosynthesis with a small contribution from the Big Bang.
D) mostly from the Big Bang with a small contribution from stellar nucleosynthesis.
E) radioactive decay of elements heavier than carbon.

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A) A sudden and extremely rapid expansion of the universe that occurred in a tiny fraction of a second during the universe's first second of existence
B) The expansion of the universe that we still observe today
C) The sudden release of photons when a particle and antiparticle annihilate one another
D) Quantum fluctuations by high speed, relativistic particles in a state of false vacuum that caused disturbances in the space-time continuum leading to the process described in the question to which this answer refers

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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 temperature over small angles.
C) Dark matter will smooth out the spectrum, but the small patches of "light" matter create fluctuations in the temperature.
D) The overall structure of the universe is very uniform, but the synthesis of different elements produces varying signatures within the background radiation.
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.

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A) You are in the center of a young star.
B) You are in the early universe before the Planck time.
C) You are floating somewhere in the universe near its end, 10¹⁰⁰ years from now.
D) You are inside the nucleus of an atom.
E) You are in the universe shortly after inflation.

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A) Scientists are not allowed to believe in God.
B) 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.
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.

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A) 10⁻¹⁰ seconds
B) 0.001 seconds
C) 5 seconds
D) 5 minutes
E) 5 years

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