PHYS 1302 CH 27 Questions
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University of Houston, Downtown *
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Course
1302
Subject
Astronomy
Date
Dec 6, 2023
Type
Pages
5
Uploaded by angeladkee
1.
Oscillations in the early universe are most similar to: water waves. sound waves. light waves. seismic waves. oscillations of stars in the instability strip of the H-R diagram. 2.
What did the cosmic microwave background tell cosmologists about the early universe? the horizon problem, in that the microwave background is almost too isotropic The dark matter in the universe is mostly baryonic in nature, for a closed Big Bang. Nothing; it is a product of the black hole in the center of our own Galaxy. the discovery of relativistic redshifts and the Big Bang the discovery of dark energy and its role in accelerating the universe 3.
The crossover point from radiation to matter domination occurred: about 50,000 years after the Big Bang, at a temperature of about 16,000 K. with the creation of electrons and positrons at about 6 × 10
9
K. with the emission of the cosmic background radiation. when the strong force separated from the other two forces. with the creation of neutrons and protons, at about 10
13
K. 4.
The redshift of the universe at decoupling was about: Z = 10. Z = 4. Z = 1,000,000. Z = 400,000. Z = 1,100. 5.
Which of these could be considered as "hot dark matter"? deuterium
neutrinos dark energy dust close to H II regions weakly interacting magnetic particles (WIMPS) 6.
Which of these orderings of the epochs is correct? quark, lepton, atomic nuclear, lepton, quark Planck, lepton, quark Planck, stellar, galactic nuclear, stellar, galactic 7.
Currently, most of the mass of the matter of the universe is believed to consist of: tiny but very numerous black holes. dark energy. dark matter not made of protons and neutrons. baryonic matter, made up of protons and neutrons. tachyonic matter, travelling only faster than the speed of light. 8.
Ripples in the Cosmic Microwave Background correspond to: matter density fluctuations. fluctuations in both matter and radiation. energy fluctuations. temperature fluctuations. imperfections in measurement techniques or equipment. 9.
At what point do the weak nuclear and electromagnetic forces split? at about four seconds, when at millions of degrees hydrogen forms helium after about 10
-10 seconds, when the temperature drops below 10
-15
K at 10
-43
seconds, when all four forces separate as the Planck Era ends
never, they are still united at 10
12
K, when pair production starts for neutrons and protons 10.
Scientists are able to use the theories of physics to describe the conditions of the universe back to: the moment of the Big Bang. the end of the Radiation Era. the end of the Planck Epoch. the beginning of GUT. the Recombination Epoch. 11.
During the nuclear epoch, the temperatures were: comparable to the temperatures inside giant stars today. between 3,000 and 16,000 K. less than 10 million K. about a trillion degrees. higher than 10
32
K. 12.
Which of these did NOT occur at decoupling? The cosmic microwave radiation was released from matter. Neutral atoms were formed. Matter dominated radiation. The universe became transparent. Electrons began to orbit protons. 13.
After the atomic epoch, and before the current stellar epoch, came: the galactic epoch, when the main events were galaxy construction. about three billion years after the Big Bang, with Population I stars forming. the liberation of the dark energy. the black hole epoch, when black holes were common.
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the end of the lepton epoch, when neutrinos were formed and escaped from matter. 14.
There is observational evidence that supports the theoretical conditions of the universe. The farthest back in the history of the universe this evidence goes is: the end of the Radiation Era. the end of the Planck epoch. the Recombination Epoch. the moment of the Big Bang. the beginning of GUT. 15.
Gravity becomes separate from the other forces at the: end of the Planck Era, about 10
-43
seconds after the Big Bang. end of electron production, about a minute after creation. end of the Inflationary Epoch, about 10
-32
seconds into creation. beginning of particle production, about .0001 seconds into the universe. decoupling Event, about a million years after the Big Bang. 16.
Pair production can occur if: only virtual particles are produced. photons are at the event horizon of a black hole. the energy of two photons is greater than the combined mass-energy of a particle-
antiparticle pair. the particle and antiparticle have opposite spins. one particle is struck by a sufficiently high energy photon that a pair of electrons is formed. 17.
What key event happened during the decoupling epoch? Electrons and positrons were created. The universe underwent a brief period of very rapid expansion. Dark energy accelerated the cosmos on to infinity. Pairs of neutrons and protons were created. Expansion cooled the universe enough that protons could capture electrons in orbit.
18.
What would help scientists probe the period from zero time to 10
-43
second? a theory incorporating the force of gravity into existing GUTs more sophisticated gravity wave detectors more detailed observations of the cosmic microwave background discovery of a white hole, with matter and energy flowing out a better understanding of the nature of dark energy 19.
The period from about one to 100 seconds after the Big Bang is called the: lepton epoch. nuclear epoch. atomic epoch. pair-production era. quark epoch. 20.
Collectively, electrons, muons, and neutrinos are called: pions. baryons. hadrons. photons. leptons.