Why "expanding space"? When the "faster with distance" view was first discovered the natural assumption was that this movement was ballistic. As far as I am aware, this remained the case for most of the rest of the 20th century. Nowadays this movement is said to be due to the expansion of space, (which, as an aside, begs the question, "where is the need for dark energy"?). So what aspect of the the original "expansion from a single point of origin, via the energy imparted by the big bang," cannot be explained without the need for either/or expanding space and dark energy?