A) We do not yet have a theory that links quantum mechanics and general relativity.
B) We do not yet have a theory that explains how the universe underwent a rapid period of inflationary expansion.
C) We do not yet have a theory that links the weak and electromagnetic forces.
D) The Planck era was the time before the Big Bang, and we cannot describe what happened before the beginning of the universe.
E) We do not understand the properties of the antimatter that would have been produced at this time.
Correct Answer
verified
Correct Answer
verified
A) unify gravity and the electromagnetic and weak forces.
B) unify the strong force and the electromagnetic and weak forces.
C) unify gravity and the strong and weak forces.
D) unify all four forces.
E) unify the electromagnetic and weak forces.
Correct Answer
verified
Correct Answer
verified
A) the same temperature it is now.
B) colder.
C) hotter.
Correct Answer
verified
Correct Answer
verified
A) Particle accelerators on Earth can reach energies equivalent to the high temperatures of the Electroweak era and have produced particles predicted by the unified theory.
B) Temperatures in the center of the Sun can reproduce the conditions during the Electroweak era.
C) The most advanced telescopes are able to see back to the GUT era in the universe.
D) Detectors on Earth have received photons and high- energy particles from the GUT era.
E) We have no direct evidence of such a unified force.
Correct Answer
verified
Correct Answer
verified
Correct Answer
verified
The Big Bang theory predicts that the un...View Answer
Correct Answer
verified
View Answer
A) the relationship between the strong and the weak force
B) how galaxies came to exist
C) the fact that our universe is expanding
D) the existence of helium in the universe
Correct Answer
verified
Correct Answer
verified
Correct Answer
verified
During the era of nuclei, the universe c...View Answer
Correct Answer
verified
View Answer
A) the fact that the universe is expanding
B) the fact that the temperature of the cosmic microwave background is almost the same everywhere
C) the existence of the cosmic microwave background
D) the fact that about 25% of the ordinary matter in the universe consists of helium
Correct Answer
verified
Correct Answer
verified
A) It had a much higher temperature in the past.
B) It was discovered by Penzias and Wilson in the mid- 1960s.
C) It has a temperature of about 3 degrees K above absolute zero.
D) It appears essentially the same in all directions (it is isotropic) .
E) It is the result of a mixture of radiation from many independent sources, such as stars and galaxies that formed within the first billion years of the Big Bang.
Correct Answer
verified
Correct Answer
verified
A) the sudden release of photons when a particle and antiparticle annihilate one another
B) 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
C) the expansion of the universe that we still observe today
D) 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
Correct Answer
verified
Correct Answer
verified
A) The spectrum of pure hydrogen gas must be a perfect thermal radiation spectrum.
B) The background radiation came from the heat of the universe, with a peak corresponding to the temperature of the universe.
C) The spectrum of 75 percent hydrogen and 25 percent helium must be a perfect thermal radiation spectrum.
D) The light from all the stars and gas in the sky averaged over the entire universe will be a perfect thermal radiation spectrum.
E) It doesn't predict that the cosmic background radiation should have a perfect thermal radiation spectrum.
Correct Answer
verified
Correct Answer
verified
A) (1) The theory predicts the existence of and the specific characteristics of the observed cosmic microwave background; (2) the theory correctly predicts the observed overall chemical composition of the universe.
B) (1) The theory correctly predicts that the universe should be expanding; (2) the theory predicts the existence of and the specific characteristics of the observed cosmic microwave background.
C) (1) The theory predicts the episode of inflation that we think occurred in the early universe; (2) the theory predicts the existence of large quantities of dark matter.
D) (1) The theory correctly predicts that the universe should be expanding; (2) the theory correctly predicts the observed ratio of spiral to elliptical galaxies in the universe.
Correct Answer
verified
Correct Answer
verified
Correct Answer
verified
Correct Answer
verified
A) An enormous amount of energy was released when the strong and electroweak forces froze out from the GUT force.
B) Large amounts of matter and antimatter annihilated at this time.
C) Gravity was an extremely weak force at this period in time.
D) The universe was too small and needed to grow quickly.
E) There wasn't enough matter present to slow down the expansion at that time.
Correct Answer
verified
Correct Answer
verified
A) By the time helium could survive, the temperature had become too low for heavier elements to form.
B) They did, but radioactive decay caused these elements to disappear again.
C) Too many high energy photons were present during the era of nucleosynthesis for heavy elements to form.
Correct Answer
verified
Correct Answer
verified
A) How many stars are in the universe?
B) What would it be like to ride on a beam of light?
C) Why is the sky dark at night?
D) Can we measure the position and momentum of an electron at the same time?
E) How does the Sun produce energy?
Correct Answer
verified
Correct Answer
verified
Correct Answer
verified
If the universe were infinite and unchan...View Answer
Correct Answer
verified
View Answer
A) It is the amount of time required for two protons to fuse to make deuterium.
B) It is the time at which inflation is thought to have occurred.
C) Before it, conditions were so extreme that our current understanding of physics is insufficient to predict what might have occurred.
D) It is the time when the cosmic microwave background was released.
Correct Answer
verified
Correct Answer
verified
A) 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.
B) 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.
C) 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.
D) Dark matter will smooth out the spectrum, but the small patches of "light" matter create fluctuations in the temperature.
E) The overall structure of the universe is very uniform, but the synthesis of different elements produces varying signatures within the background radiation.
Correct Answer
verified
Correct Answer
verified
A) It has a perfect thermal radiation spectrum.
B) It contains prominent spectral lines of hydrogen, the primary chemical ingredient of the universe.
C) Its temperature is a little less than 3 Kelvin (3 degrees above absolute zero) .
D) Its temperature is the same everywhere, except for small variations at the level of 1 part in 100,000.
Correct Answer
verified
Correct Answer
verified
Showing 21 - 40 of 96
Related Exams