As Ramana would point out, we need not try to explain something which is not real in the first place. Ajata says that not any thing has ever been created, from the very beginning. Any thing which could take on the appearance of having been created would therefore not really exist, in truth; it would be an illusion.
Let’s examine such a situation, using an analogy. Picture that you are asleep and dreaming. In the dream, a baby is born and you understand that it is you: you are living in a world that is part of a universe. There are other people, there are objects in the environment, there are events, and you are conscious of what takes place internally and externally. Time, space, cause and effect are present.
In this dream, you are now a child. You are in a car with your parents, on your way to San Diego to attend the funeral of an uncle. So, even death is in this dream.
You wake up. All of this panorama was a product of your mind; its creation was entirely within the mind of the dreamer; not anything in it was a substantial or concrete reality. Though an illusion, it appeared to be true. If asked, you would not have denied that you were real, in a world that existed.
Now that you are awake: if asked, you would not deny that you are real, nor that the world and universe you are in truly exists.
So, what could be called the big Dream (with a capital D) is the Dream in which your “reality” in a sleeping dream is not substantially different from your “reality” when you are awake. Neither exists, in truth, apart from you and your mind, or consciousness.
Where not any thing has actually ever been created, from the start, this would include the universe, the world, you, your mind, any thing, even time, space and cause and effect. Thus, birth, life, and death are not truly real. Not any thing exists, beyond the appearance of existing. An illusion is “real” as an illusion, but it is not real beyond its appearance of being real.
So, in the big Dream, the dreamer himself is not apart from the Dream, he is within the Dream. The dreamer in an unreal Dream, who is herself equally unreal, is not in a position to ask about reality.
But what can be said is this: everything within the sleeping/waking Dream has no ultimate reality, beyond its appearance. If there were anything which could be said to actually be true, it would have to be beyond, or “outside” of, the Dream. In other words, from the standpoint of the Dream or its dreamer, it would have to be a negative: void, nothingness, emptiness. That is to say, reality would be on the other side of what is not real. Put another way, it would be something which does not make an appearance.
As Ramana said, we do not need to explain that which has no reality, the Dream and its appearances. But when we awaken from this Dream illusion, it will be clear to us that not any thing which occurs within this Dream really matters ultimately.
What is ultimate reality is outside of the dream, and that would be a void. A state in which not any thing has been, or could be, created would be utter emptiness.