Answer the following question: Answer the following question given this paragraph: About 13.7 billion years ago, the entire universe was packed together. Everything was squeezed into a tiny volume. Then there was an enormous explosion. After this "big bang," the universe expanded rapidly ( Figure below ). All of the matter and energy in the universe has been expanding ever since. Scientists have evidence this is how the universe formed. One piece of evidence is that we see galaxies moving away from us. If they are moving apart, they must once have been together. Also, there is energy left over from this explosion throughout the universe. The theory for the origin of the universe is called the Big Bang Theory . Q: The once compressed universe expanded rapidly after what nicknamed event billions of years ago? A:
Answer:
big bang