Laws of physics can change or new ones be added. Its just a set of rules humans set in physics, but that's only based off of the physics that humans know now. Once AI comes in, all kinds of new knowledge about physics come in, developing new knowledge, and changing our own laws of physics/modifying them. So according to our current laws of physics, a shrink ray might be impossible, but with how intelligent AI would become, it could find and learn new physics that we're not even close to, then possible from that.