Sometimes the response to a Christian supporting an old universe is along the lines of "The God I worship wouldn't take 14 billion years to create the universe." The implication, of course, is that the old-earther worships a different god, i.e. he's a heretic. The tempting response is: "The God I worship wouldn't need such a long period as six days, He could do it in six pico-seconds if He wanted."
We all assume that is true. But is it? Is it possible that God had to take 14 billion years to prepare an earth for human inhabitation?
Before you light the torches and storm the gates, let me explain.
Theologically speaking, we know that there are things God cannot do. Principally, He cannot sin.
There are other limitations, as well. Logically (or philosophically) speaking, most agree that God is "above" logic, but whatever that means, it does not mean that God is illogical. The main point here is that He cannot violate the Law of Non-contradiction: God cannot be something and its opposite (A and not-A) at the same time and in the same context. Thus the answer to the age-old conundrum: Can God make a rock so heavy that He cannot lift it? is no, for God cannot be both omnipotent and non-omnipotent at the same time and in the same context.
Present super-string theories postulate that space-time is 10 (or 11) dimensional, and we live in a universe where all but three distance dimensions and one time dimension are "compactified"—which means we can't see them. Anything existing in the other dimensions (perhaps heaven, and hence God, and hell) would be mostly invisible—yet may appear to us by intersecting with our dimensions. This is just like Flatland. A 3D sphere is invisible to the 2D inhabitants of Flatland, unless the sphere intersects the 2D universe, in which case it appears as a circle.
Suppose God created a three-space, one time dimensional universe for us to inhabit, and the laws of physics to go with it. Is it possible that the universe is then destined to evolve by those laws, and it must, because God cannot create laws and violate them at the same time?
Note that miracles and divine intervention in human affairs are not precluded. To the inhabitants of Flatland, a circle appearing out of nowhere was miraculous (and a physical reality). Miracles could involve God stepping into (intersecting) our universe, stepping into time as we like to say.
In other words, what I described is a universe that would evolve by its God-given laws, and in which miracles were possible (even vaguely understood) but which had laws that God could not violate, because He made them. He cannot make moral laws and then violate them; perhaps the same applies to physical laws.
Folks, this is just pure speculation.