The String Theorists and the Loop Quantum Gravitators are busily chipping away at the problem what space-time actually is. For some time, my concern has been that if people can figure out how space-time is put together, then somebody might be able to figure out how to take it apart. In other words, the next paradigm shift in theoretical physics may have weapons implications, just like the last one, which gave us nuclear weapons. The atomic nucleus is not Nature's last word on explosive energy release.
That last word is actually the First Word - the Big Bang that began the Universe as we know it. The question is whether some yet to be discovered physics can yield intentional explosions between the intensity of a nuclear explosion and the Big Bang.
On the other hand, our astronomers are finding that planets orbiting around stars are commonplace. With all those planets out there, surely some are home to technological civilizations, and surely some of them have already discovered physics that is several paradigms beyond our own. If there were any explosive technology based on such physics, and if any extra-terrestrial civilization had used it, our astronomers would have seen it. So far, all the observable explosions and other energetic phenomena in space look natural. Or so we think.
Maybe theoretical physics isn't such a dangerous pursuit after all. Maybe.