Astronomy 10 Quiz 12, Spring Semester 2008
Cuesta College, San Luis Obispo, CA
Astronomy 10 learning goal Q12.4
[3.0 points.] Which one of the following choices best describes the evidence for the sudden early inflation of space in the universe?
(A) Stars in the inner and outer parts of the disk orbit the center of the Milky Way with the same speed.
(B) Each and every galaxy sees all other galaxies moving away from its location.
(C) Nearly equal amounts of cosmic background radiation are detected from all directions.
(D) Distant galaxies appear to be much younger than nearby galaxies.
(E) Type Ia supernovae in distant galaxies appear to be dimmer than expected from their redshifts.
Correct answer: (C)
Response (C) is the horizon problem of the cosmic background radiation, which may be explained by being a very small portion of the universe inflating suddenly and briefly to become the extent of the visible universe today. Response (A) is evidence for dark matter; response (B) is a reason why the expansion of the universe can be said to have no center; response (D) is a result of the finite speed of light ("lookback time"); while response (E) is evidence for the recent acceleration of the universe's expansion rate, caused by dark energy.
Student responses
Section 4160
(A) : 3 students
(B) : 4 students
(C) : 10 student
(D) : 0 students
(E) : 19 students
Showing posts with label dark energy. Show all posts
Showing posts with label dark energy. Show all posts
20071226
Astronomy quiz question: dark energy evidence
Astronomy 10 Quiz 12, Fall Semester 2007
Cuesta College, San Luis Obispo, CA
Astronomy 10 learning goal Q12.3
[3.0 points.] Which one of the following choices best describes the evidence for the existence of dark energy?
(A) Stars in the inner and outer parts of the disk orbit the center of the Milky Way with the same speed.
(B) Each and every galaxy sees all other galaxies moving away from its location.
(C) Nearly equal amounts of cosmic background radiation are detected from all directions.
(D) Distant galaxies appear to be much younger than nearby galaxies.
(E) Type Ia supernovae in distant galaxies appear to be dimmer than expected from their redshifts.
Correct answer: (E)
Since type Ia supernovae in distant galaxies appear to be dimmer than expected from their redshifts, this shifts the slope of the Hubble plot for the long-ago (distant) universe, compared to the recent (nearby) universe. Thus the expansion rate of the universe has been accelerating recently, and this is the evidence for dark energy.
Response (A) describes the evidence for dark matter in the halo of the Milky Way. Response (B) is the consequence of an expanding universe. Response (C) describes the "horizon problem" of the cosmic microwave background, and is the evidence for the inflation era of expansion. Response (D) is the consequence of the finite speed of light.
Student responses
Section 0135
(A) : 4 students
(B) : 3 students
(C) : 13 students
(D) : 2 students
(E) : 7 students
Cuesta College, San Luis Obispo, CA
Astronomy 10 learning goal Q12.3
[3.0 points.] Which one of the following choices best describes the evidence for the existence of dark energy?
(A) Stars in the inner and outer parts of the disk orbit the center of the Milky Way with the same speed.
(B) Each and every galaxy sees all other galaxies moving away from its location.
(C) Nearly equal amounts of cosmic background radiation are detected from all directions.
(D) Distant galaxies appear to be much younger than nearby galaxies.
(E) Type Ia supernovae in distant galaxies appear to be dimmer than expected from their redshifts.
Correct answer: (E)
Since type Ia supernovae in distant galaxies appear to be dimmer than expected from their redshifts, this shifts the slope of the Hubble plot for the long-ago (distant) universe, compared to the recent (nearby) universe. Thus the expansion rate of the universe has been accelerating recently, and this is the evidence for dark energy.
Response (A) describes the evidence for dark matter in the halo of the Milky Way. Response (B) is the consequence of an expanding universe. Response (C) describes the "horizon problem" of the cosmic microwave background, and is the evidence for the inflation era of expansion. Response (D) is the consequence of the finite speed of light.
Student responses
Section 0135
(A) : 4 students
(B) : 3 students
(C) : 13 students
(D) : 2 students
(E) : 7 students
20071221
Astronomy quiz question: dark energy destiny
Astronomy 10 Quiz 12, Fall Semester 2007
Cuesta College, San Luis Obispo, CA
Astronomy 10 learning goal Q12.3
[3.0 points.] Which one of the following choices best describes what dark energy may eventually do to the universe in the distant future?
(A) The expansion of space will continue forever, until matter fades away, or is torn apart.
(B) The expansion of space will eventually slow down and stop, and begin contracting as galaxies and stars collide in a "Big Crunch."
(C) Eventually produce enough antimatter to annihilate all matter in the universe.
(D) Stabilize the expansion caused by inflation, such that universe will remain the same size.
(E) Stabilize the contraction caused by dark matter, such that the universe will remain the same size.
Correct answer: (A)
Dark energy is responsible for the recent accelerating expansion of space in the universe. As dark energy is apparently created by space itself, the expansion of space creates more dark energy, which would in turn accelerate the expansion of space, etc. Thus the expansion would steadily increase such that universe would be subject to a "Big Rip" or "Big Tear," as distant galaxies and nearer galaxies recede faster than the speed of light, disappearing from our view, and then locally the expansion of space would rip apart matter itself, overcoming attractive gravitational, electromagnetic, and then nuclear forces.
The "Big Crunch" response (B) had previously been the prevailing prediction for the fate of the universe, before the discovery of accelerating expansion caused by dark energy. For a closed, matter-dominated universe, gravitational forces could eventually overcoming the expansion of space, resulting in slowing down, stopping, and possibly reversing the expansion of space.
Student responses
Section 1073
(A) : 16 students
(B) : 20 students
(C) : 2 students
(D) : 5 students
(E) : 2 students
Cuesta College, San Luis Obispo, CA
Astronomy 10 learning goal Q12.3
[3.0 points.] Which one of the following choices best describes what dark energy may eventually do to the universe in the distant future?
(A) The expansion of space will continue forever, until matter fades away, or is torn apart.
(B) The expansion of space will eventually slow down and stop, and begin contracting as galaxies and stars collide in a "Big Crunch."
(C) Eventually produce enough antimatter to annihilate all matter in the universe.
(D) Stabilize the expansion caused by inflation, such that universe will remain the same size.
(E) Stabilize the contraction caused by dark matter, such that the universe will remain the same size.
Correct answer: (A)
Dark energy is responsible for the recent accelerating expansion of space in the universe. As dark energy is apparently created by space itself, the expansion of space creates more dark energy, which would in turn accelerate the expansion of space, etc. Thus the expansion would steadily increase such that universe would be subject to a "Big Rip" or "Big Tear," as distant galaxies and nearer galaxies recede faster than the speed of light, disappearing from our view, and then locally the expansion of space would rip apart matter itself, overcoming attractive gravitational, electromagnetic, and then nuclear forces.
The "Big Crunch" response (B) had previously been the prevailing prediction for the fate of the universe, before the discovery of accelerating expansion caused by dark energy. For a closed, matter-dominated universe, gravitational forces could eventually overcoming the expansion of space, resulting in slowing down, stopping, and possibly reversing the expansion of space.
Student responses
Section 1073
(A) : 16 students
(B) : 20 students
(C) : 2 students
(D) : 5 students
(E) : 2 students
20070809
Heat death of the universe
Dinosaur Comics, by Ryan Northwww.qwantz.com
July 18, 2007 (excerpt)
Astronomy 10 learning goal Q12.3
Ryan North hits another one out of the park, astronomy-wise, in describing the heat death that will result from the expansion of the universe (exacerbated by the acceleration due to dark energy?), imagined here as a "Choose Your Adventure." But at least there is a happy ending in the last panel.
Previous post: comment on Ryan North's Dinosaur Comics discussion of the tidal slowing of Earth's rotation.
20070730
Valuable lesson learned
Wigu, by Jeffery Rowland
jjrowland.com
June 23, 2007 (excerpt)
Astronomy 10 learning goals Q12.4
Is Blingidium meant to be made of dark matter, dark energy, or something else entirely?
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