I'm reading the relativistic mechanics chapter, of Hestenes' New Foundations for Classical Mechanics. After the derivation of relativistic doppler shift is some general discussion of applications. The last of which (4) discusses Hubbles law: "distant galaxies are receding from the Earth with velocities proportional to their distance from the Earth" The text then mentions that these velocities are "one of the main empirical supports for the Big Bang Theory". I don't quite see how a point in time measurement of velocities is enough to build a model of an always expanding/exploding universe. The big bang ideas aren't really discussed in detail in the text (this part of the book is about application of spinor/clifford algebras to relativity which is quite enough to get your head around by itself). If the galaxies we can see are currently (ie: were previously) moving outwards, I'd imagine that this could be a part of an oscillatory or more complex motion. Additionally, I could imagine that there would be universe with different motion characteristics outside of the range that we can perceive with our telescopes. My Dad always angrily proclaimed the big bang as absurd (religious bias), but like my grade school teachers who (somewhat religiously) taught this as fact without saying the reasons, he also didn't have any good reasons to call it absurd. I suppose that some of this doubt wore off on me, but until now I never thought much about it. The engineer in me ignored the whole topic because it can't be used to do or build anything. I don't really want to get too sidetracked on this issue, since my immediate goal is to understand enough of the relativity to work with e&m intelligently. However, I am curious at a high level, especially given the pervasive acceptance of the big bang theory, what rules out more complex motion?