“By poking a quantum field in one tiny region of space, it’s possible to turn the quantum state of the whole universe into literally any state at all. Technically this result is known as the Reeh-Schlieder theorem, but it has also been called the Taj Mahal theorem. That’s because it implies that without leaving my room, I can do an experiment and get an outcome that implies there is now, suddenly, a copy of the Taj Mahal on the moon. (Or any other building, at any other location in the universe.)”