Is our universe a two-dimensional hologram? It sounds like science fiction straight from “The Matrix,” but scientists are checking out the hypothesis for real. So far, the answer is no.
The experiments are being conducted at Fermilab in Illinois, using a gnarly-looking device known as the Holometer. The apparatus is designed to measure the smoothness of spacetime at lengths down to a billionth of a billionth of a meter. Put another way, that’s a thousand times smaller than the size of a proton.
The standard view is that the fabric of reality is continuous – but some theories propose that spacetime is pixelated, like a digital image. If that’s the case, there’s a built-in limit to the “resolution” of reality.
The Holometer uses a pair of high-power laser interferometers to look for tiny discontinuities in movements that last only a millionth of a second. Such discontinuities would provide evidence of holographic noise, or quantum jitters, in spacetime.
This week, a research team reported finding no discontinuities. But Craig Hogan, a professor at the University of Chicago who heads Fermilab’s Center for Particle Astrophysics, said that doesn’t yet rule out the holographic hypothesis.
“This is just the beginning of the story,” he said in a Fermilab report on the experiment. “We’ve developed a new way of studying space and time that we didn’t have before. We weren’t even sure we could attain the sensitivity we did.”
Some physicists were skeptical that the Holometer could have found anything:
— Sabine Hossenfelder (@skdh) December 4, 2015
@NautilusMag claims that the holometer can probe quantum gravity are dubious. It's a good experiment, but it doesn't do that.
— Jonah Miller (@thephysicsmill) October 31, 2015
The fact that the instrument observed the smoothness of spacetime on small scales at least demonstrated that it could tune out the thousand shocks that such instruments are heir to – for example, the rumble of road traffic and seismic perturbations.
Fermilab’s Aaron Chou, project manager or the experiment, said the apparatus uses design elements from the Laser Interferometer Gravitational Wave Observatories, but on a smaller scale. “No one has ever applied this technology in this way before,” he said. “A small team, mostly students, built an instrument nearly as sensitive as LIGO’s to look for something completely different.”
Hogan said the Holometer will check out other hypotheses – relating to the holographic universe as well as gravitational waves. The device will also lay the groundwork for more instruments of its type. “It’s new technology, and the Holometer is just the first example of a new way of studying exotic correlations,” Hogan said. “It is just the first glimpse through a newly invented microscope.”
In addition to Chou and Hogan, the authors of “Search for Space-Time Correlations from the Planck Scale With the Fermilab Holometer” include Richard Gustafson, Brittany Kamai, Ohkyung Kwon, Robert Lanza, Lee McCuller, Stephan Meyer, Jonathan Richardson, Chris Stoughton, Raymond Tomlin, Samuel Waldman and Rainer Weiss.
Hat tip to Gizmodo’s Jennifer Ouellette.