Is the Universe Expanding?

Dark energy is just the name given to this anomalous expansion which we haven't explained. We don't know that there is a source of pressure or that these observations are caused by something pushing on the universe and so on. But with the prevailing theories of what dark energy does, never mind what it is, but what it does, the universe is not expanding into anything. The universe is the length scales in the universe are increasing intrinsically. And some of the present theories say that it is in fact infinitely large and that it is infinitely large and homogeneous so that the total amount of matter in it is infinite.