Ooh, oohooh! This is one of my favorite concepts to explain. Randyjp, I'm going to have to make some assumptions about your understanding of what the BBT says, and in turn, I'll ask that you accept that my offered explanation assumes no god exists. I'm not even going to ask you to agree or disagree, I'm just going to ask you to consider this as a possibility (keeping in mind that I DO assume no gods exist). You seem reasonably intelligent so here it is:
1. Time is a concept, an idea, an abstract. It doesn’t exist in the way people often speak of it; for instance, no one ever “ran out of time”. At worst, one could run out of life, but time continues to pass, regardless of any individual’s participation, or lack thereof. It’s not an actual thing; it’s a way of explaining other things.
2. Earth is a planet in the Milky Way galaxy, which is one galaxy of many (no, seriously, MANY) in the universe. For this conversation, we’re not going to include such theories as the multiverse – this one is enough for now.
With me so far? I'm assuming that none of that is controversial to you, and I’m sure that others who are far better equipped to dig into the fine points will correct any errors I make.
If we can agree that black holes exist (an assumption of agreement here), and function as described by science - very generally: given enough time they absorb whatever is in their path - then follow that as far as it can take you.
Given enough time (and yes, I do take for granted that the universe is at least billions of years old), even black holes will be sucked in to other black holes. Eventually, all matter that exists in the entirety of the universe gets sucked into a single immeasurably dense/intensely pressurized/mind-bendingly squished teenytinydot.
Can you guess what would happen next?
A big frickin’ bang, that’s what.
This universe is not the first universe created by a "big bang", it's just the current universe.The problem with trying to insist on a beginning is that it's all built on a concept - time - that only exists to allow us to communicate about things related to it, like “yesterday”, or “next month” or “in ten years”. Or “many millions of years ago”. Or “one hundred twenty seven light years away”.
Without humans to come up with the concept of "time" in the first place, "beginning" is rendered meaningless. The "beginning" described by the Big Bang Theory is an explanation that fits the empirical evidence we've amassed to date, and the extra bit that I pointed out above fits as well and invalidates the entire idea of beginning.
I also want to be very clear that in no way am I presenting this as a fact. It's an alternative explanation that addresses your question, without the inclusion of a god. Nothing more, but also nothing less.