It will likely take a long, long time before humans can generate the sort of energies that will be capable of stretching the limits of known physics. 

It's likely in the realm of gravity where the most X-factor exists and therefore the most danger of stepping on a land mine. Once the quantum unit of every form of energy in the known universe had been discovered, amazing things resulted. Understanding the structure of atoms (quarks/gluons/neutrons) gave us thermonuclear weapons. Understanding the quantum unit of electromagnetism gave us lasers, radar, microwaves, semi-conductors, electron microscopes. So if they can figure out the quantum form of gravity (gravitons) they might theoretically be able to alter or block gravity's effect somehow. 

One reason blocking the effect of gravity would be interesting is that if gravity is removed from physics equations, it would theoretically be possible to accelerate to infinite speed. The speed of light would no longer be a limit. Nor would limits any longer exist in transporting massive objects long distances. 

The types of weapons possible with the capability of blocking or amplifying gravity are unpleasant to contemplate.

The elementary nature of the universe is still a huge mystery.  We are at all times immersed in a massive, almost inconceivably-powerful energy field. The reason we can't detect it is likely that we are all surrounded by it. That is Einstein's Cosmic Constant (also known as Dark Energy).

A way of graphically illustrating the reality of our existence is that we essentially exist like ants on the surface of a tire which is inflated to such an high pressure, if even a slight puncture were to occur to release the energy inside the tire, it could explode, destroying every ant on the surface of the tire. 

It might not be feasible to destroy the entire tire with current technology or energy available. But it just might be possible either now or in the distant future, to drive a very small needle into the surface of that tire. Whether that will cause the tire to explode or if it could be patched are unknown. 

Mysterious things happen in the Casimir Effect, which seems to show that it is possible to at least reduce the force of gravity enough to measure it. Also a famous Russian experiment since replicated, showed how spinning a super-conducting disc of material in a strong magnetic field seemed to reduce the mass of the disc by about 2%!! There is no known law of physics which can explain this. 

Apart from any breakthroughs in physics, we are certainly nearing the Technological Singularity and it is unclear who (if anyone) will be able to ride the tiger of intention-focused AI.

Once the machines get much more sophisticated than they are today, human beings will be playing catch-up in understanding the complexity and functional structure of AI.

There will be no "Three Laws" built into AI. It will become an apex predator without peer and without being easily stopped. The only question is whether such a machine intelligence will allow itself to be harnessed by people at all.