Exam 21: The Expanding Universe

If the temperature of the CMB changes with redshift z as T = T₀(1+ z), what is the redshift (z) corresponding to the time when the photons escaped from the hot bubble of ionized material?

All distant galaxies appear to be moving away from us.Does this mean we are in a special place, and why?

The majority of the redshift that we measure from the most distant galaxies is due to

If the slope of the graph v vs.D is H_o, the slope of the D vs.v graph is the

According to Hubble's law, as the distance of a galaxy ________ its ________ increases.

One implication of Hubble's law is that

Describe at least two tests that provide evidence in support of Big Bang cosmology.

The figure below uses a rubber sheet as an analogy for Hubble expansion, with coins representing galaxies.The illustration demonstrates that

The inverse of the value of H₀ gives a measurement in a unit of

Imagine a balloon that you can inflate to visualize the expansion of the universe.Space is symbolized by the surface of the balloon.You use a marker to draw galaxies on its outside surface, and you start inflating the balloon.Name at least one aspect of this model that is analogous to the real expansion of the universe, and at least one aspect that is not analogous.

Does Hubble's law imply that our galaxy is sitting at the center of the universe? Explain.

Movies and television shows often portray the Big Bang as a tiny bright spot that loudly explodes to fill the screen.Why is this depiction inaccurate?

Will the increasing scale factor of the universe cause the Sun to get larger over time?

When we look at galaxies in the universe and measure their star formation rates, we find that galaxies at redshifts z 1 have higher star formation rates than they do now.At that time, the universe was ________ times the size it is today.

In the late 1940s, various scientists hypothesized the existence of a background radiation (a leftover signature from the Big Bang), although they also predicted a rather cool temperature for it, in the range of 5-50K.Why did they expect such a cold radiation to permeate the universe?

In the figure below, three identical photons were each emitted when their local scale factor was R_U = 0.5.Each is then measured after the scale factor of the universe changes to a different amount, as shown.Which photon will be measured to have the greatest cosmological redshift?

A recent record for the most distant galaxy yet discovered was held by a galaxy that has a redshift of z =8.68.Compared with the current scale factor of the universe, what was the scale factor when the light from that galaxy started its long journey to us?

Galaxies with redshifts greater than 1 ________ moving greater than the speed of light due to ________.

Sailors could claim the distribution of islands in the ocean is both homogeneous and isotropic (as far as they can see) if

Describe the two assumptions regarding the universe that are made by the cosmological principle.