How to explain the existence of an effect without a cause? For example, if we track back the creation of the Big Bang, and the creation of the creation of the Big Bang, we reach a point where an entity is created without a cause.
Actually, this is not true.
It's not that the Big Bang did not have a cause; it's that our understanding of physics breaks down at that point. In other words, the Big Bang may well have been caused by something, we just have no way of knowing what that something was with our current understanding of physics.
Also, cause and effect implies a uni-linear view of time. In reality there's only ONE law of physics that can only work in one direction of time; the second law of thermodynamics, also known as the law of entropy.
That law states that in any closed system, the system tends from order to chaos over time. (Hawking defines 'chaos' as the potential number of ordered states that can explain a system state, so it's not what we semantically view as chaos)
Newton's third law (every action has a equal and opposite reaction) works both ways through time; if you reverse time, then the actions of the particles being observed are still consistent with that law.
So, cause and effect are concepts that help us make sense of our universe, but don't necessarily mean that the universe is bound to a particular sense of linear time the way we perceive it.
'Cause' and 'effect' are conceptually joined. You can't have an effect without a cause since to call something an effect is to imply that it has a cause - and to call something a cause is to imply that it has an effect. This belongs to the logic of the two concepts.
However, there can be events without a cause. It is not the case that every event has a cause, not as a matter of language or logic anyway.
Also, the so-called uniformity of nature - 'same cause, same effect'- does not follow.
We don't know anything sure about the Big Bang and what have caused it, no one can say what have been before it. May be something have accumulated for trillions years before to reach the "boiling point" of the Big Bang? No one knows.
Sometimes an infinitesimal small change can lead to an enormous effect which may seems without a reason or correlation to the initial cause - the butterfly effect. For example a small droplet of water can cause a giant dam wall to crack, if the pressure is on the point where infinitesimal small increase will lead to a break. But is this single droplet the cause? Or the cause is the whole process which have led to the precondition? I have experience many times such butterfly effects while I was fixing my car, something breaks very unexpectedly and seemingly without a reason but this is because the accumulation of neglect and incompetence have led to a precondition something small like a little stone on the road to break the whole car. Who can say if the effect is caused by a long process or by the stone on the road?