Our existence could be coded in a finite bandwidth, like a live ultra-high-definition 3-D video. And the third dimension we know and love could be no more than a holographic projection of a 2-D surface.
A scientist’s $1 million experiment, now under construction in Illinois, will attempt to test these ideas by the end of next year using what will be two of the world’s most precise clocks.
Skeptics of a positive result abound, but their caution comes with good reason: The smallest pieces of space, time, mass and other properties of the universe, called Planck units, are so tiny that verifying them by experiment may be impossible. The Planck unit of length, for example, is 10 billion billion times smaller than the width of a proton.
Craig Hogan, a particle astrophysicist at Fermilab in Illinois, isn’t letting this seemingly insurmountable barrier stop him from trying.
Hogan is following through on a radical idea to confirm Planck units with two of the most precise clocks in the world. Deemed holometers, each L-shaped laser interferometer will have two perpendicular, 131-foot-long arms to scan for pixelation in the very fabric of space and time. If it’s there, two laser beams (split from a single source) that run through the arms won’t hit a detector at the same time.
“What we’re looking for is when the lasers lose step with each other. We’re trying to detect the smallest unit in the universe, ” Hogan said. “This is really great fun, a sort of old-fashioned physics experiment where you don’t know what the result will be.”
The two holometers, now being built in an earth-covered tunnel on Fermilab’s prairie-covered campus, will initially be stacked almost on top of one another to listen for the same Planck-scale “noise.” Once the machine is calibrated and environmental interference is accounted for, Hogan says it should only take a matter of minutes to see if the devices simultaneously see it.
Should Hogan’s team detect something significant, they will then separate the machines and run the experiment all over again. If the noise they measure next isn’t correlated between the machines, it could be the calling card of a limit to space-time’s resolution.
Inspiration for the holometer came from such a noise picked up by an experiment called GEO600. Designed to detect gravity waves — ripples in space-time caused by things like colliding black holes — the machine is a laser interferometer like the holometer will be, yet has arms 15 times longer and a laser designed to detect lower frequencies (to be sensitive to gravity waves, if they exist).
“In the past, [Hogan] became a little bit driven, even excited for some time, that this noise could be a result of the holographic principle, ” Grote said.
The holographic principle, derived from weirdness theorized to occur at the boundaries of black holes, says reality could be a 3-D projection of a 2-D plane of information. It’s much the same way a hologram printed on a credit card creates the illusion of a 3-D object but, as Hogan explained, we can’t perceive the 2-D surface.
“We could be living inside that 3-D projection, with the truer vision of it as a 2-D sheet hidden by scale, ” Hogan said.