Image by Ralph Buckley via FlickrThere are three inventions that might not even be possible, but given them in conjunction, would grant engineers absolute omnipotence. Given all three of these things, it's only a matter of time before I'm creating entire universes.
First, a zero point energy generator. This might not even be possible. Energy is like the money of physics, and there have been a few clues that it might be possible to have negative energy as well as the positive kind that we're familiar with. If so, then from a "zero point" of no energy, you could draw off and separate arbitrary amounts of negative and positive energy, which would have to be shuttled off in opposite directions, as they would nullify each other on contact. However, negative energy hasn't been shown to really exist, and might make about as much sense as making money by sending out checks for negative amounts of money and somehow collecting when the checks are cashed in.
The first thing I'd do with zero point energy would be the mundane energy use, running the air conditioning, refrigerator, and lights with the energy, and do experiments with the negative energy. Could I run my computer on anti-electricity, and if so, would it absorb heat instead of producing it?
The next thing would be a matter condenser, that would change energy into hydrogen. Since E=MC^2, this would ensure an unlimited supply of materials. Of course, this would not be worthwhile without the unlimited energy from the zero point system.
The third thing would be some sort of teleportation system to make arbitrary manufacturing. It would have to teleport together raw materials to make things, such as combining a few grams of carbon from charcoal, hydrogen and oxygen from water, and nitrogen from air to form a hot dog. It would also need to be able to scan new patterns and store them in a computer. This also might not be possible due to the Heisenberg uncertainty principle, in which knowing the exact position of an atom requires unpredictably altering its velocity and vice versa.
My power with these things would grow exponentially. First I'd use the teleporter/replicator to scan the three inventions and be able to arbitrarily produce more. Then I'd start scanning useful tools, which I now have in arbitrary amounts. Then, having proven its safety, I'll start handing them out because other people deserve this too. And next, I'd start designing entire star systems, which I teleport into existence. If I want to visit them, a matter-condenser rocket will take me there, accelerating to preposterous speeds with a zero-point-energy plus matter condenser, producing a stream of supercompressed hydrogen gas.
I'd send probes to go deep into the void, make a ring of trillions of matter condensers that was several AU in diameter, and spray hydrogen into the center to create stars. When the star grows enough, the welding on the ring fails and the matter condensers go flying outward into the universe. I'd recharge the sun by swapping out large amounts of it for a fresh cube of hydrogen. The heat death of the universe would never occur, because we would continuously rebuild it from scratch.