1.What is the cosmic light horizon? a.the farthest distance to which light can have traveled since the first human campfires b.the farthest point from which light can have traveled to the Earth in the age of the universe c.the surface around a supermassive black hole within which no light can escape to the outside universe d.the farthest distance light can travel before being completely absorbed by matter in the universe 2.The cosmic microwave background radiation was first detected a.accidentally using a ground-based communications antenna. b.accidentally using a satellite that was launched to monitor above-ground nuclear explosions. c.using a microwave antenna on the roof of a building at Princeton University. d.using a satellite that was launched to test predictions by cosmologists that we should be bathed in a sea of radiation from the early universe. 3.The temperature of the cosmic microwave background is 2.725 K. At what point in the history of the universe did the radiation cool to this temperature? a.24,000 years after the Big Bang began, when the universe ceased being dominated by radiation b.10-43 second after the Big Bang began, when the laws of physics first allowed a definite temperature to exist c.380,000 years after the Big Bang began, when the universe became transparent and radiation was able to travel freely d.now (the present day) Solution 1. The cosmic light horizon is the farthest point from which light can have travelled to the earth in the age of the universe,. The answer is option B. 2. using a microwave antenna on the roof of a building at Princeton University. Arno Penzias and Robert Wilson were using a supersensitive 20 ft horn antenna. The answer is option C. 3. It is the present day temperature of the universe. The answer is option D..

1. 1.What is the cosmic light horizon?
a.the farthest distance to which light can have traveled since the first human campfires
b.the farthest point from which light can have traveled to the Earth in the age of the universe
c.the surface around a supermassive black hole within which no light can escape to the outside
universe
d.the farthest distance light can travel before being completely absorbed by matter in the
universe
2.The cosmic microwave background radiation was first detected
a.accidentally using a ground-based communications antenna.
b.accidentally using a satellite that was launched to monitor above-ground nuclear explosions.
c.using a microwave antenna on the roof of a building at Princeton University.
d.using a satellite that was launched to test predictions by cosmologists that we should be bathed
in a sea of radiation from the early universe.
3.The temperature of the cosmic microwave background is 2.725 K. At what point in the history
of the universe did the radiation cool to this temperature?
a.24,000 years after the Big Bang began, when the universe ceased being dominated by radiation
b.10-43 second after the Big Bang began, when the laws of physics first allowed a definite
temperature to exist
c.380,000 years after the Big Bang began, when the universe became transparent and radiation
was able to travel freely
d.now (the present day)
Solution
1. The cosmic light horizon is the farthest point from which light can have travelled to the earth
in the age of the universe,.
The answer is option B.
2. using a microwave antenna on the roof of a building at Princeton University. Arno Penzias and
Robert Wilson were using a supersensitive 20 ft horn antenna.
The answer is option C.
3. It is the present day temperature of the universe.
The answer is option D.