This topic is a good one, but the questions are more philosophical than scientific. It's unfortunate that this thread was placed in a science forum, because I fear that science itself will provide no useful answers to the questions. The statement that "everything which begins to exist has a cause" is a philosophical statement made by philosophers. It cannot be properly discussed without delving deeply into philosophy.
Utter rubbish. Come on Kirk, I expect better from you. Causality is 100% physics but "cause and effect" is philosophical nonsense. It is a high-level emergent property of the Universe, not some deep underlying "truth" - at least, according to our current understanding. Your "The Metaphysics of Causation" article is so Newtonian it's ridiculous. Again, that is fine as a way of categorising emergent properties, but these philosophers seem to think they are doing so much more.
In terms of understanding existence, physics left philosophy standing decades ago (not to say that physics has all the answers - far from it)
Cause and Effect is a concept born of our anthropocentric experience. We drop a cup, it falls to the floor and smahes into thousands of shards. It is easy to assign the dropping as cause and the smashing as effect; it is utterly counterintuitive to reverse those roles. And so we learn to assign causes and effects, and feel that behind those things we call effects should lie something to which we can assign the term cause.
But this is only true at the macroscopic level. At the quantum level, everything is time reversible. What appears as cause can just as easily appear as effect. An electron and a positron annihilate to create two photons. Two photons pair-create an electron and positron out of the vacuum. The exact same process viewed in two opposite directions through time.
In fact, as we build up these interactions into something much more complex, we realise that there is no cause and effect as such, but simple consistency. One can say that the effect requires the cause, but there is just as much validity to say that the cause required the effect. Causality is simply a constraint on what parts of the interaction have to be consistent with what other parts.
We can see almost exactly this behaviour in looking at the open ocean. Look at the waves criss-crossing the surface. Can you spot any obvious cause and effect? Waves are entering the area under observation, interacting, moving off away again. Assuming none of the waves are breaking, if we run a video of the waves backwards, could you notice?
What then creates this great disparity between the macroscopic view and the microscopic view? Principally the same macroscopic thing that gives rise to the idea of time: entropy.
When the cup falls and smashes, it takes one path through the space of all possibilites to end up in the smashed state. One path out of a gazillion possible paths. And where just about every one of those gazillion paths ends up in a macroscopically identical state: cup smahed into thousands of shards and scattered over the floor, each piece having come to rest by interacting with elements of the floor and passing over the kinetic energy.
It is completely possible for each element of the floor to interact with a neighbouring shard of cup, to impart just the right amount of kinetic energy to make each shard leap together to form a perfectly formed cup - the energy being sufficient to re-create all the chemical bonds that were brokern in the fall, and being sufficient to lift the cup back into the air back into our hand.
How possible? Just about as equally probable as it was for the cup to fall and smash in the way it did! One in a gazillion.
The difference is that the particular path that leads to the cup resurrection is surrounded by a gazillion paths that look nothing like a cup resurrection, where-as the path that our cup took on its fall was surrounded by a gazillion other paths that all looked essentially the same - a cup falling and smashing.
Why is there such a difference between the space of possible paths in the two cases - smashing and resurrection? That comes down to how special it is to have a "cup" in the first place. You may want to think about what properties the Universe needs in order that at some point it contains a "cup".
The point is that the cause could well be the floor imparting kinetic energy to a bunch of shards and the effect is the creation of a cup in someone's hand - this, from the point of view of the physics, is just as valid as the cause being the dropping and the effect being the smashing.
What we should be thinking is that the smashing is consistent with the dropping, or that the unsmashing is consistent with the catching of the resurrected cup.
This is an enormous subject and I'm just scratching the surface here with this rather rushed and semi-coherent piece. But you cannot talk about a "cause" for the Universe without first appreciating "causes".
Why is it more absurd to posit that there is no exception to the rule of cause and effect than it is to posit that there is an exception?
Ignoring for the moment the absence of any real "law of cause and effect", this is the classic category error of these cosmological arguments. Cause and effect, in as much as it exists, is a function of the space-time structure of the Universe. How then can cause and effect have anything remotely to do with the space-time structure itself? It is like asking "Any point on Earth has a point west of it. So which point is west of the Earth?"
It is just nonsense to assume the universe could exist for any period of time as a singularity. And it is pointless nonsense. Nothing is to be gained by the speculation. The theory makes no prediction and adds no insight to our knowledge.
And you have been told repeatedly that is a completely incorrect representation of the Big Bang. The Big Bang singularity can no more exist for a period of time as the geographical North Pole extend over a range of lattitudes.
The mathematics of the BB model breaks down at the singularity because of infinity but the laws of physics do not necessarily break down. Heat rises and expands in our universe, correct? Like charges repel each other? The electromagnetic force is more powerful than gravity, yes?
There is no reason to believe any of these would be different when the universe was in its earliest moments.
There is every possible reason. Just for starters, we are dealing with a region of the Universe where there is no electromagnetic force (we are way above the energy scale where EM appears) and we may well be dealing with a region surrounding topology change.
What triggered the change? Why would the universe, stable for aeons...
Again, a hopelessly incorrect view of the Big Bang.
I would like to see you evidence that the energy scale is way above where EM appears.
How basic are we here? Would you like me to "evidence" that the sky is blue as well? Anyway, SG has answered this. Other than that, go read a book on cosmology, there are many.
I have read a number of physicists who have described the big bang as a flash of heat and light.
They are not physicists. They are better described as idiots.
How many microseconds after the expansion begins would EM be able to appear in your opinion?
In my opinion? I don't have an opinion. I simply know the answer. At least, the answer as we currently accept it. In microseconds, much much much much much much less than 1 microsecond. Again, SG has provided a more precise answer.
However, from the perspective of a realm where we could watch colliding branes creating numerous universes, it would be theoretically possible but physically impossible. Do you agree or disagree?
It is not about agreeing or disagreeing with you. It is about *telling* you.
The singularity, as others have explained, is a *point* at which our modelling of spacetime becomes undefined. It is no more an object than the North Pole, which is also a singularity: that where the lattitude and longitude grid system breaks down.
If we have a larger playing field, such as the multi-dimensional space-time of M/String-Theory, then the time dimension of our Universe is inherited from the time-dimension of the larger space-time. In this case, there will be a temporal ordering of events, such as the collision of two branes that catalyse the "beginning" of our own little universe. But there will be no singularity; just a region of space that undegoes rapid expansion owing to the collision. So now we have an infinite space-time and no possible "point" of creation.
Alternatively, there may be no larger space-time in which our Universe is embedded. The singularity may be a point of topology change, where the Universe "rounds-off" and past directed time-lines flip around and become future-directed time-lines, just as north-directed lines of lattitude become south-facing lines of lattitude as you move towards and then across the North Pole. Rahvin has just mentioned this very point. Such topology changing points are not always handled well within classical General Relativity, and it is no wonder that the basic mathematics breaks down at this point. So we have a finite space-time, yet no possible "point" of creation.
In either case, we have no "cause" of the Universe. The Universe just is. And "causes" are things entirely constrained to be within these Universes.
Of course, there are other options: millions of them, and some even make some sort of sense. But the only one that looks anything like Biblical creation is the good-old classical Big bang cosmology, and that's the one we know for sure, thanks to its singularity and non-quantum nature, is wrong
William Lane Craig has provided his own gerrymandered definition, but he has not supplied the extra argumentation required. For one thing he has failed to even show that our universe has a beginning by his special definition !
Can you please provide Craig's definition, and a reference to where he presents this definition? Are you sure that he has not supplied the extra argumentation? (How can you be sure unless you've read everything he's written?)
Missed this earlier. Let me just state that having read much of WLC's material, and (briefly) conversed with him on the net, he has absolutely zero clue about cosmology at the required level to be able to coherently discuss this subject. His Kalaam arguments, his arguments against past infinite time, all complete nonsense. He's been told repeatedly (by me and others), he has nothing to say in response, and yet continues to use these arguments. That makes him academically bankrupt in my book.