Although it sounds entirely like something dreamed up in a smoke-filled dorm room, whether the entire universe is a hologram is a very serious question—a question that gets at the heart of a fundamental problem in physics. A new experiment just starting up Fermilab just might hold the answer.
Fermilab, a government-funded research campus on the prairie outside Chicago, might be best known for having the highest energy particle accelerator in the world—until the LHC superseded it in 2009. Since then, Fermilab has made itself busy with physics projects smaller in physical size but no less ambitious. Craig Hogan's Holometer experiment is one of them. For years now, Hogan has been building a pair of L-shaped instruments underground to measure "noise" that could prove the holographic principle.
Top view of the Holometer
What, exactly, is the holographic principle? Glad you asked—pull up a chair, get comfy. The holographic principle is an idea could reveal how to reconcile Einstein's theory of gravity (aka general relativity) and quantum physics. General relativity governs at the grand scales of planets and galaxies, while quantum physics governs at tiny scales smaller than an atom—there must be an overarching theory that unifies the two.
The holographic principle says that 3D space is a hologram that emerges from information imprinted on a 2D surface. This information is stored as bits—like in computers—but at scales 10 trillion trillion times smaller than an atom known as the Planck scale. "According to Hogan, in a bitlike world, space is itself quantum—it emerges from the discrete, quantized bits at the Planck scale," explains Michael Moyer in Scientific American. "And if it is quantum, it must suffer from the inherent uncertainties of quantum mechanics. It does not sit still, a smooth backdrop to the cosmos. Instead quantum fluctuations make space bristle and vibrate, shifting the world around with it."
The interferometers that make up the Holometer.
Hogan's Holometer is designed to measure those fluctuations, or in a wonderful turn of phrase, the "quantum jitter of space." A laser beam of light is split down the two arms of two L-shaped instruments called interferometers. Those beams are then compared for any interference, which could be a sign of the jitter of space.
Images courtesy of Fermilab