DASI will give us definitive answers. What I am most interested is in using DASI to test models for the origin of the universe. The theory that DASI will test is called the inflationary theory. It is an explanation of the start of the big bang. It boggles my mind.
Light travels through space without any problems.
You probably are comfortable thinking of light coming from stars through space and detected in your eyes. That is, you see stars. Well light from very very far away that came from very hot gas is what DASI detects. You can see similar light too, for example when you look at flames from a fire. It has been travelling almost since the beginning of the universe.