How was this picture of the supposed entire universe taken in infrared? Also, why does it seem as though almost all of the matter is in a line formation over the center? It makes sense why most matter would be concentrated in the center, but why is it in a line?
This picture was taken by the WISE (Wide-field Infrared Survey Explorer) space telescope. It is in deed an infrared picture of the entire universe but what you see in this line is our home galaxy, the Milky Way.
This telescope has taken infrared pictures of the entire Universe (as we see from the Earth) and joined them in this full-sky view.
As other people said, what you see in that picture is a mosaic of images, centered in our Galaxy, produced with WISE observations in infrared light. Astronomers have used a projection method, called Aitoff, to project the spherical sky into a 2-dimensional map.
For a more detailed explanation of the image, please follow this link:
PS: Sorry that my reputation doesn't allow me to put more than two links.