Just a little follow-up to Clever Apes episode #16 (“New dimensions”), in which we consider whether the universe is actually a hologram, and if so, how we might know. The effect that Fermilab theoretical physicist Craig Hogan is looking for in his holometer is a jitter – a kind of noise – that would indicate that spacetime is not smooth, but rather made of tiny grains or pixels.

It’s hard to imagine what this “noise” would sound like, but Hogan has given us a hint. He’s simulated the signal in the spectrum they expect holographic noise would have, and slowed it down by about a factor of 3000 so it’s audible. Here is the sound of our two-dimensional universe:

Of course, it’s important to remember that this remains in the realm of theory. Hogan did identify some noise in a German gravitational wave detector a few years ago that he said could plausibly be holographic noise, but that machine wasn’t sensitive enough to the right effects to say so with much confidence.

The holometer, meanwhile, continues apace. The team got a new batch of funding that will help build the prototype and perhaps more. And speaking of milestones, allow me to draw attention to the holometer’s YouTube channel. It includes this footage of the machine’s first laser lock, including Hogan high-fiving a collaborator. Please also note an unnamed physicist crying out, “Booyah!”