I was still under the impression that what caused the big bang is still pretty much a mystery?
Again, you need to be careful what exact question you are asking.
Scientitists consider the Big Bang as starting from a point when the entire universe was a singularity with super high energy density which rapidly expanded outwards, cooled and allowed matter to form. The proof of this, the understanding of the physical processes, the mechanisms are relatively well understood. Much more so than the genral public expects. The Big Bang is actually quite well understood. There is a lot of observational evidence to support it:
http://en.wikipedia.org/wiki/Big_Bang#Observational_evidence
It is called a theory but you need to understand what a scientitifc theory is to appreciate it. The word "theory" does not have the same meaning in science as common speach.
If you are asking how that initial state came to be, then there is much more speculation but not without scientific value. There is just a lot of difficulty surrounding this for various technical reasons. This is the point where many christains that beleive in science point to God as the answer, i.e., he planted the "seed" of the universe and controls the processes. I wont argue against such a point of view but one should note that it is absolutely not required for such a magical process to explain this initial state.
There are actually quite a few competing scientific theorms to explain this stage, its not that scientists don't have an explanation, they have have lots of explanaions but have a hard time unifying different concepts.
An important point here is that in general the human mind cannot grasp certain concepts. Example include imagining a 5 dimensional cube (let alone 11 dimensional, 100 dimensional) but arbitrary dimensional geometry is mathematically trivial. Most of us don't fathom the idea of infinity, and inseatd imagine it just to be very, very big. Hence, all the infinity +1, infinity x 2, etc. stupidity. We also have a hard time to imagine that outside the physical universe there is absolutely nothing, no existence, no time, no space. Most people just imagine that outside the edge of the universe it is just empty space, it is not, it doesn't even exist in the commen sense.
So it is not at all surprsing that most of us find it hard to beleive that all of a sudden the universe popped into existence from nothingness, but scientifically this is plausable, and other fantsatical ideas are also possible such as multiverses.
