You know when you’re having sex and you’re getting pretty boisterous and suddenly you hear a small rap-a-tap-tap from the other side of the wall? That’s your neighbor reminding you of reality: that you are not alone in the universe and that the barriers of sound do not end where you think they do. That same kind of startling revelation freaked out some German and British physicists who built a couple barn-size boxes connected to trenches that were supposed to use a beam splitter to detect gravitational waves. No such ripples were found. Instead, the beam splitter had an "extra sideways jitter," unexpected but consistently-placed noise with frequencies between 300 and 1500 hertz that may literally be the sound of the edge of reality as we know it (and if you’re curious what that might sound like, go here and start clicking around). Which could mean that our entire world is a hologram, and we’re all just a projection of some distant, unknown 2-D surface. So that’s what happens when you start fucking gravity really loudly—the universe literally comes a-knocking to show you how space-time emerges out of quantum theory, reminding you who’s boss around here.