Have you ever had a sneaking suspicion that the universe is just one giant hologram? For better or worse, this now seems less likely to be the case, according to the latest results from a gravitational wave detector. Yes, we have those.
The holographic universe idea essentially argues that our entire universe is little more than a three dimensional projection originating from a two dimensional surface out at the universe's edge. That's right, you, me, everybody and everything is just a projection. It's not crazy, it's physics, and it's apparently a very serious question.
To figure out whether this is the case or not, scientists have started looking for the "pixels" that make up our reality. Since the "projector" (the two dimensional edge of the universe) is way, way out at the very edge of space, the idea is that just like an LCD projector, the very long projection distance might cause spacetime to get a little bit more pixelated than it should be, and the closer you look, the fuzzier things get. It's this "fuzziness" on the quantum scale that we may be able to detect.
When we're talking about things on the quantum scale, it goes way, way beyond microscopically small. Fortunately, we have some instruments that have been designed to peek at those infinitesimally small scales, like the GEO600 gravity wave detector in Germany, which was designed to search for "gravity radiation" emitted by things like colliding black holes.
This detector is so sensitive that it can pick out fluctuations in space amounting to one single atomic radius over a distance from the Earth to the sun. A 2009 set of data from GEO600 revealed some suspicious looking interference that led some researchers to suggest that the instrument might have accidentally detected some of those holographic pixels.
However, more recent data from ESA's Integral space-based gamma ray observatory, which is able to see how much gamma rays get twisted by spacetime, suggests that the GEO600 interference might be caused by something else. If spacetime is made of pixels, those pixels will twist gamma rays more and more the further they travel. If, on the other hand, spacetime is smooth, the gamma rays won't twist at all, and this is what Integral observed.
Don't worry, though. There's an instrument under construction at Fermilab in Illinois that aims to put this whole holographic universe idea to rest once and for all. Fermilab's holometer should be able to detect the smallest units (of space, time, mass, or anything else) in the universe, called Planck units, which are something on the order of 10 billion billion times smaller than a proton.
The holometer consists of two laser beams split from a single source along with two ultra-precise clocks, and if they switch it on (by the end of this year) and the laser beams get even slightly out of sync with each other, they should be able to actually measure the degree of pixelation of spacetime.
So what happens if the universe does turn out to be a hologram? Probably nothing. It'll be fun to think about, if our brains are capable of truly comprehending such a thing. Just for heaven's sake don't say "computer end program" out loud lest you completely destroy our entire reality.