I was caught in a debate today at work, "god vs science".

Eventually we hit a stale mate when we got to the big bang. My arguement was that if this was the beginning of it all, what caused the big bang? And what caused whatever caused the big bang etc etc.

My friend then said "why does there have to a beginning, why cant something just be.

And so, my question...how can something exist without having a beginning or an end?