[SketchySeaBeast]

If we don't assume a beginning or end, then we end up with infinite time, with infinite variations, and with that it's a pretty much certainty that this would exist as it does, for this iteration.

Science and Engineering rely on cause and event largely in mathematical abstractions - if we draw the line out far enough "why is that real ball moving through space" the answer stretches all the way back to the big bang, and we lack the ability to see what came before. From what I understand of current science - the theory is that it was due to a big crunch, which was due to a big bang - infinite loops in an infinite cycle.

Again though, you're saying that the singular uncaused occurred just because - in a system that otherwise must have a cause and effect that MUST have had a cause and effect, unless you decide to draw a special case for it, where I can see no reason why you would. It's basically a special pleading to jam god into a hole of knowledge, just like we used to do with demons and witches before we understood the real nature of diseases.