I guess it would be like a computer life simulation. There is no way that the creatures who live and evolve in the simulation could ever step out of the computer and surpass the programmer who made them. They are inherantly limited by the program of the system in which they live while the programmer (God) exists outside of it and can change the physical laws of their world at will. (or by clicking his cosmic mouse button)
there's a great deal of philosophy surrounding that precise debate... and even more science fiction. it's actually a kind of terrifying idea, but is it really impossible?