YouTube geeks about Cosmic Microwave Background. And here is what I posted in the comments:
"Why is it that this earliest of light, or microwave background, still in our neighborhood? What's it been doing all this time? Shouldn't it have sped off into uncharted space long ago, leaving matter, like galaxies, suns and planets, such as Earth, in it's wake? Surely microwaves travel faster than galaxies."