A lot of people have a problem with the Big Bang. The commonest question I hear is "what came before it?" and often the answer to this is that the Big Bang created the universe, so there was nothing before it.
Now this is unsatisfying for the simple reason that we live in a universe of Cause & Effect, and our lives are ruled by this constant. For every thing that happens, there was something that caused it to happen. However the Big Bang seems to instantly violate this deeply-held belief. Well actually it's not even a belief, it's more of a Cosmic Law. Everything has to have a cause. Strangely people don't seem to have a problem with the idea of God having been around for ever and not being created by anyone, but they don't seem to be able to accept the same thing for a universe.
Anyway, leaving religious convictions aside, what is it about the Big Bang that people actually don't like? Well it's basically the idea that because the universe must have been created by something, therefore there must have been something before the universe to have created it. Aristotle did attempt to address this issue with the concept of the first mover or primum movens, but that ultimately ends up as God again, which is as unsatisfying as the idea of the universe being created from nothing.
Right. So the first thing to be aware of (and people don't like this either) is that what appears to have been created in the Big Bang is not just all the matter and energy in the universe, and not just the universe itself, but the space that the universe is contained in, and the time that passes within it. Ever since Einstein it's been pretty much a certainty that space and time aren't different things, but are actually separate components of Space-Time. And that's what was created in the Big Bang. Space-Time.
So now we have a situation where there was no "before" the Big Bang, because there was no Time. Even if we could somehow get round the idea of the "something" that created the Big Bang somehow existing "before" when there WAS no "before", we still have the problem of "where" that something existed, as there was no Space for it to exist in.
If there wasn't a place to put the Cause of the Big Bang, and there wasn't a time for it to happen, then we now have the Big Bang as, by definition, the first thing that ever happened in the universe. So it couldn't have had a cause.
Still unsatisfying, isn't it?
At this point, let's take a slight diversion, and look at exactly what we mean by "Cause and Effect". Well, it's fairly simple isn't it? An "Effect" is "Caused" by something that happens before it. Let's examine that sentence. It implies that two events occur, separated by a length of time, and one causes the other. However it is not actually implied that one of these events happens "before" the other.
I know that seems a crazy thing to say, but it's actually an assumption based solely on the fact that in our normal every day world this is how we see things happen - the Cause always proceeds the Effect. But this assumes that there is always a definite absolute order of events, in that we see Cause and Effect always taking place in the correct order. However this isn't always the case.
Special Relativity tells us that not only is the order that events occur dependent on how they are being observed, but that we cannot know which absolute order events occur in, as there is no absolute order. All events occur in relation to observers and other events. That's why it's called Special Relativity. Thus in a universe with a finite speed of light it is perfectly possible for an event to be perceived as occurring before the event that caused it
If we step momentarily into the realm of speculation we can even conceive of events which quite plainly and in-arguably take place in the "wrong" order. For example, I win the Lottery on Saturday. I then go back in time and give myself the winning numbers on Thursday. Which came first? Which caused which?
Admittedly we don't have the ability to travel in time (at least not yet), but this does show that although it may be important to our world view that all events have a cause, it's not quite as important which order they occur in, or even how long the time gap between them is, providing the events and the relationship between them are consistent.
So let's look at that old Big Bang again. We'll forgo the argument that there can't have been a cause to the universe because there was no "before", and let's assume that the Big Bang did have a cause. Does it matter "when" this cause occurred? Well we'd like it to be "before" the Big Bang, as that satisfies our expectations of Cause preceding Effect, but as we've already seen, this doesn't have to be the case. Is there any chance that the Cause of the Big Bang occurred After the Big Bang? Well if you follow my "Lottery" example, then it's possible, but then we run into the thorny problem of describing such a mechanism.
However, by definition, the Big Bang was the 1st Event ever. So if that was the case, then the Cause of it couldn't have happened before, not only because there was no before, but because that would make the Cause of the Big Bang the 1st Event ever, and that would be impossible...since the Big Bang is already defined to be 1st. So we now have the situation that the Big Bang couldn't have been caused by either a prior event, or a later one. Back to square one.
Not quite. What if the event that caused the Big Bang occurred at the same time, and in the same space as the Big Bang? We've already established that the order in which Cause and Effect occur is irrelevant, so long as the events themselves are logically consistent. So why can't they have occurred at the same time? Why can't the Cause and Effect of the Big Bang be the same thing?
If there's ever going to be any candidate for the process that instigated the largest single detonation in the history of the Universe, then a massive explosion of energy creating both the space the event occurred in and the time it took must be a pretty big one. The Big Bang created Time, which enabled the logic of Cause and Effect to work, and it created Space for Cause and Effect to exist in. Not only that, but at the precise single instant that this happened, the cause of the Big Bang, and the effect of that cause (the Big Bang itself) must have both happened at the same time.
So there we go. Our concept of Cause and Effect still works perfectly consistently, so long as we accept that the time interval between the thing that caused the Big Bang, and the Big Bang itself was so small as to be non-existent, and that's not a difficult concept to handle, is it?