The microwave background has a spectrum similar to that of
Thermal radiation form a cool body
The temperature of the background radiation is nearly
The intensity of the microwave background radiation is greatest in the direction of
Nowhere; it is the same all over
The existence of the cosmic background radiation implies that
On a large scale the universe appears the same to all observers
The assumption that the general structure of the universe looks the same from all locations over sufficiently great distances is the assumption of
The assumption of isotrophy states that
The universe looks the same in all directions over sufficiently great distances
Which of the following is NOT a basic assumption made in modern cosmology?
The universe is infinite in extent
Which of the following observations is NOT important to modern cosmology?
Everything appears to revolve around the Earth
In order for matter to be produced directly from radiation,
The total energy of the photons must be greater than the energy-mass equivalent of the particles that are formed
The critical density is
The density of a flat universe
If the density of the universe is greater than the critical density the universe will
Eventually stop expanding and begin contraction
As the universe cooled, it eventually reached a temperature of 3,000 K and protons were able to capture and hold electrons to form neutral hydrogen. This process is known as
What was the temperature of the universe when the recombination took place that produced the cosmic background radiation we observe today?
A large amount of deuterium in the universe would mean the universe is
What percentage of the mass of the universe was formed into helium during the Big Bang?
When we observe distant galaxies we are observing
Very young objects
Except for hydrogen the most abundant element formed in the Big Bang was
Deuterium in the universe was produced
In the Big Bang
Why is it important to determine the cosmic abundance of deuterium?
All of these
From outside, the primeval fireball would have looked small, hot, and dense.
Misleading: the fireball filled space, and could not be viewed from “outside”
The cosmological principle states that the universe is homogeneous on a large scale. Which of the following are we sure is the largest scale on which the universe does not appear homogenous?
Clusters of galaxies
Which of the following indicates that the universe might be open?
The Deuterium abundance is too high to have a closed universe.
During the Big Bang, the most massive particle which we would expect to have been made it
A helium nucleus
In 1998, it was announced that the expansion of the universe is accelerating. What does this imply from the perspective of the big bang?
A force exists that we knew nothing about that causes the expansion