What are the four forces that operate in the universe today? Why do we think there were fewer forces operating in the early universe?

Answer the following questions based on the information provided.
How much cooler is the universe now (at an age of $4\times10^{17}$ s) than it was at an age of 1 second?
a. Its current temperature is one hundred-millionth ($10^{-8}$) the temperature at an age of 1 second.
b. Its current temperature is one hundred-thousandth ($10^{-5}$) the temperature at an age of 1 second.
c. Its current temperature is one-hundredth ($10^{-2}$) the temperature at an age of 1 second.
d. Its current temperature is one ten-billionth ($10^{-10}$) the temperature at an age of 1 second.

The Avis Company is a car rental company and is located three miles from the Los Angeles airport (LAX). Avis is dispatching a bus from its offices to the airport every 2 minutes. The average traveling time (a round trip) is 20 minutes. How many Avis buses are traveling to and from the airport?

How do the galaxy types found in clusters of galaxies differ from those in smaller groups and those of isolated galaxies?

Describe the appearance of the Milky Way as you would see it both from Earth and from a point directly above or below the galaxy. Why does the galaxy look different from different vantage points?

Choose the best answer for the following question.
Which of the following does not provide strong evidence for the Big Bang theory?
(a) observations of the cosmic microwave background
(b) observations of the amount of hydrogen in the universe
(c) observations of the ratio of helium to hydrogen in the universe

Choose the best answer for the following question.
When a proton and an antiproton collide, they
(a) repel each other.
(b) fuse together.
(c) convert into two photons.

Choose the best answer for the following question.
The charge of an antiproton is
(a) positive.
(b) negative.
(c) neutral.

Choose the best answer for the following question.
The current temperature of the universe as a whole is
(a) absolute zero.
(b) a few K.
(c) a few thousand K

Decide whether the statement makes sense (or is clearly true) or does not make sense (or is clearly false). Explain clearly.
Patterns in the cosmic microwave background tell us about conditions in the early universe that ultimately led to galaxy formation.

The figure illustrates two different sequences of sedimentary rock strata located some distance apart. a. Determine the geologic range/age of each rock layer by its fossil content and write your answer on the figure. b. Draw lines connecting the rock layers of the same age in outcrop $1$ to those in outcrop $2$. c. What term is used for the process of matching one rock unit with another of the same age?

d. Based on the ages of the rock layers in outcrop $1$, identify an unconformity. Remember that an unconformity is a break in the rock record. Draw a wavy line on the figure to denote the unconformity.

Name each of the rocks shown in the figure and name the rock group to which each belongs.

Name the foliated metamorphic rocks shown in the figure and list their names in order from lowest to highest metamorphic grade.

Match each term or characteristic with the appropriate rock group:

A. Foliated texture

B. Clastic texture

C. Gneissic texture

D. Chemical rocks

E. Porphyritic texture

F. Lithification

G. Alignment of mineral grains

I. Vesicular texture

J. Strata or beds

K. Felsic composition

L. Slaty texture

M. Glassy texture

N. Evaporite deposits

O. Detrital rocks

Igneous rocks: ____. Sedimentary rocks: ____. Metamorphic rocks: ____.