Origins #4

One concept in this book that I just could not wrap my head around was cosmic microwave background radiation, or CBR. I have heard it mentioned many times before in other science texts, but I have never really understood what it is. "Origins" actually does not do a very a good job of explaining what this concept is. The book's lack of information is probably due to the authors simply assuming that the reader already knows what the CBR is. Although the authors explain all other concepts beautifully, they could use some work in their explanation of the CBR. Many things in the past two chapters I have read have depended on the reader understanding this concept; the CBR tells scientists many things about the Big Bang and other such things. So I decided to just look the CBR up on the Internet to supplement the information in the book. I found that cosmic microwave background radiation is just microwaves in space that astronomers are able to see through special telescopes. The Big Bang theory says that when the universe was still very dense and hot, there was an abundance of plasma that caused the universe to look opaque. As the universe cooled, the plasma cooled as well, emitting thermal radiation. Because atoms cannot absorb this thermal radiation, it has stuck around until modern times.