One subtle consequence of the Turing-machine-like nature of reality is there aren't necessarily starting or end conditions.  In the case of our hypothetical sentient being living in its virtual world, we could have decided either to create an emergent world with its own laws of physics and evolution - starting with something equivalent to a "Big Bang" and slowly evolving a living world from there.  We could also have a team of programmers and artists craft the virtual world by hand, perhaps endowing the sentient being with some pre-programmed "instincts" in order save us the possible billions of years of virtual evolution it would take to arrive at this place otherwise. 

For the sake of this discussion, I will refer to the first kind of universe as an emergent universe - one that begins with something analogous to a Big Bang, and any kind of sentient beings living in it have evolved (both biologically and cosmologically) from a much simpler state.  I will refer to the second kind of universe as a non-emergent universe.  In this sort of universe sentient beings and there environs spring "out of nowhere" - you can think of the rules and data for this universe as having been randomly generated in such a way as to spawn something resembling hand-crafted environs and pre-programmed intelligences (or as being actually hand-crafted - but then they would be a sub- or child-universe with a parent universe whose inhabitants did the crafting).

Of course, the concept of "evolving from a much simpler state" is subjective enough that on some level emergent and non-emergent universes are the same thing.

Applying these concepts to our own universe, it brings into question the validity of extrapolating backwards in time to the Big Bang.  We must admit that it is entirely possible that our universe is not an emergent universe, and that it "started" at some later point - the seeming logic behind the distribution of matter and energy being pure coincidence.  And in light of the infinite number of possible universes, I would even go far as to say that it is absolutely true that there exists a world seemingly identical to ours (from the perspective of the inhabitants) that has only existed from this very instant forward, and that its inhabitants have incorrectly concluded that the apparent rules (physics) and data (matter and energy) are even applicable any time before this.

Given all of this, I wonder (but cannot say definitively) if there is a point at which the study of the physical origins of our universe cease to make sense.  It may be that this study is analogous to Pac-Man trying to figure out what happened before the Atari was first plugged in.  Did the universe really begin as an infinitely large field of glowing pellets?

By similar logic, there is no rule that says a universe must end at a certain time, go on for ever, loop repeatedly, or ping-pong back on itself.  For all anyone knows there may be a "line of code" in our universe that dictates everything spontaneously stop five minutes from now - and again, it is likely true that there is a universe that has exactly this fate! 

None of these are especially comforting thoughts from the perspective of the sentient inhabitants of these universes, but they must be strongly considered, especially by those sentient beings with a concern for their own survival or the survival of their progeny.