It was supposed that “energy” is a physical capability to perform mechanical work, and it was believed (on the basis of a limited number of experiments) that it was conserved through physical and chemical changes. But then, Sadi Carnot demonstrated that it is not possible to transform heat (which is “a form of energy”) integrally into mechanical work. There is always a part of it which cannot be transformed. Still, the name “energy” was kept for heat; even for that residual part of it which cannot do any work. Just imagine: an “energy” which is ineffective. And that is physics! (I mean, the phenomena is real, but the terminology needs some refinement).
But even assuming that energy, as a physical capability to perform work, were conserved, such property would not imply that energy did not need to be created. It just would imply that after the creation God did not need to add more energy to the world periodically to keep it moving, as Descartes and Leibniz used to say.
As for time and God, I am quite astonished at the way in which you and others talk about these high subjects as if you were talking of your daily experiences. Naturally, I find your words so empty…
Anyway, when Aristotle dealt with the problem of change, he invented the concepts of act and passive potency. And he said that a being in act is capable of actualizing a being in passive potency. This way, a wise man is able to teach his wisdom to other persons. If he possesses wisdom he remains “unchanged” in the sense that the perfection of his wisdom remains with him; and he is unchanged in that sense when he teaches his disciples, even if they are many. It is his wisdom which allows him to act upon his disciples actualizing them. A being who is “pure act” is unchanged (or immobile) in that same sense even if he performs any action. It is his pure actuality which allows him to act. I don’t know from where came the childish thought that a being who is pure act becomes unable to perform any action, as if he were pure passive potency instead of pure act.
As for the popping up of something into existence without a cause, that doesn’t happen even in your delirious imagination, because when you imagine such an event, it is you who is putting into scene the supposedly “uncaused” object. You remind me of that man who counting the persons in a room always forgot to include himself in the counting (because he did not see himself), and still said “we are five!”.