Depending on the physics or metaphysics you subscribe to, infinite or eternal may be reality. In the physical universe we may live behind an “event horizon.” It’s possible there is a secret universe hiding behind some information barrier (inflation). Think of the universe as existing on the surface of a ballon. There is an horizon.Someone is blowing up this ballon. As it gets larger, the surface stretches and points formerly close together become further and further apart. There isn’t a real “center” of the universe, but everything is getting further from everything else. Space itself is expanding. Another interesting thing is going on: the further stuff is from you, the faster it is moving away from you. Space is expanding locally, not into some extra dimension and not by pushing out some “edge.”
But is space infinite? It is difficult to tell. But the point is, it may be, and that makes it reasonable to think of the infinite as more than just a mental construct perhaps. The data we perceive and interpret is a brain-mental process. The models we use to order that data often involve extremal properties that suggest the infinite.
But there are other reasons to consider the infinite “real.” Much of Mormon theological thought considers “time” a property always attached to both God and man. From Joseph Smith’s time, Mormon thought has contained a thread that appeals to both an infinite past and an infinite future. While special relativity suggests that frame of reference here is vital, it is also essential that “time” exists wherever the material exists. Since Mormonism is clearly in the camp of embodiment for God and certainly for Christ (no temporary Augustinian body here). Personal time is a fact for the mind in Mormonism. You “existed” before the physical state as a material being (some sort of matter). Moreover the claim that man and God are coequal in temporal extension that they share an infinite “past.” Further, there is good textual evidence for that existence to be beginningless. Not in the sense of classical theism as a way to reconcile some of the antipodes of Christology, but in some objective sense.
Physically we deal with time in chunks. Seconds, hours, and so on. We divide up seconds in to small pieces to increase accuracy of various things. In science, we see time in a Newtonian way (I’m not referring non-relativistic physics here). It is a totally ordered “thing” with events occurring along a “time line.” Is there a practical limit to that sort of thing? In the sense of measurement, yes.The problem is, it is just not clear if motion is somehow “continuous.” The question leads us to consider what it means to subdivide time “forever.”
The infinite as a reality? Certainly possible and theologically credible, even necessary. So, next time we’ll learn to parse it a bit. Once we get a little skill with that, we can come back to some of the questions that are below the surface of our theological claims.
(Part 6 is here.)
 Interested in more detail? See Lineweaver and Davis, Scientific American March 2005. “Misconceptions about the Big Bang.” A more technical version is in this interesting paper in astro-physics archive. I’m avoiding the multiverse speculations here. M theory will have to wait.
 As kids, my cousin and I used to sit around the campfire late into the night discussing what the boundary of the universe might be like. Was it like a big rocky sphere? What’s “beyond” it? After all, we had W. W. Phelps to go on.
 Edwin Hubble (1889-1953) is famous for cementing the view of an expanding universe. Hubble was a pioneer in another sense: his study of nebulae showed that the Milky Way was merely one among many galaxies.
 I think this belief may be overblown and I’m hazy about it in terms of it’s historically authoritative basis.
 Questions of memory and things like “what were you doing all that time?” are interesting, but I won’t approach them now. It is pretty obvious too, that if you subscribe to exhaustive foreknowledge for God, then you subscribe to an infinite actual knowledge base. Analytic philosopher David Braine’s book The Reality of Time and the Existence of God (OUP, 1988) seeks to account for Aquinas’ claims in a more formal setting and offers an interesting approach to God. A useful read I think.
 There is popular language referring to “nonlinear” time. This may reference something meaningful, I don’t really know. But I do know that it tends to be an escape hatch for the uninitiated. That is a rabbit hole we shall *not* go down.