Chapter 22, Problem 1VSC

Part b

To determine

The approximate temperature of the universe at an age of 5 minutes.

Answer to Problem 1VSC

Solution: Option (c) ${\text{10}}^{\text{9}}\text{K}$

Explanation of Solution

According to the information provided in the graph the correct option from the given list is (b) about ${\text{10}}^{\text{9}}\text{K}$ .

Conclusion: From the graph, the approximate temperature of the universe at an age of 5 minutes is ${\text{10}}^{\text{9}}\text{K}$ .

Part c

To determine

How much cooler is the universe now (at an age of $4\times {10}^7$ s) than it was at an age of 1 second?

Answer to Problem 1VSC

Solution: Option (a)

Explanation of Solution

From the graph, the temperature at 1 second since Big Bang was ${10}^{10}\text{K}$ and the temperature of the universe at $4\times {10}^7$ is 1 K. Hence, the correct option is (a) its current temperature is one ten-billionth ( ${10}^{-10}$ ) the temperature at an age of 1 second.

Conclusion: The universe is ${10}^{10}$ times cooler than it was at the age of 1 second.