Shown following are several times in the history of the universe. rank these times from left to right based on the average temperature of the universe at each time, from coolest to hottest.

I believe that the question came with the following options:

- today
- 500,000 years after the Big Bang
- 100 million years after the Big Bang
- 1.5 billion years after the Big Bang
-  1 million years after the Big Bang

All we need to solve this question is to know that the universe started off very hot and got cooler with time!

So from the coolest to hottest:

1) today

2) 1.5 billion years after the Big Bang

3)  100 million years after the Big Bang

4) 1 million years after the Big Bang

5) 500,000 years after the Big Bang