“How big is G‑d?” sounds like a child's question, but adults often carry the same picture: a very large being somewhere beyond a very large universe.
Jewish thought rejects the premise. Size belongs to created things. G‑d is not one object inside space, not even the largest object. Space itself is created.
Modern physics makes the scale of creation hard to imagine, from subatomic structure to billions of galaxies. Computing adds another intuition: the cost of tracking a system rises with its complexity. We instinctively assume that attention paid to the whole must come at the expense of attention paid to the individual.
That tradeoff belongs to finite minds. G‑d does not need to divide His attention between a galaxy and one person's prayer. Neither is computationally expensive to the Creator, because “expense” and “capacity” are limits within creation.
This is why divine providence is not made less plausible by the size of the universe. The One sustaining every law of nature is not too busy to know one life.
G‑d is not infinitely big. He is beyond the category of size — and close enough to be addressed.