Look, I’m going to give it to you straight: time crystals are confusing as hell. They’re a new phase of matter that basically extends the rigid, periodic structure of crystals into the fourth dimension—time. Unlike normal crystals, you can’t hold a time crystal in your hand. Instead, they require a complex laboratory set up that involves trapping ions with lasers. You’ll probably never use a time crystal in your daily life, but they have the potential to be the basis for a nearly perfect memory system for quantum computers.

In short, time crystals are completely esoteric and totally revolutionary. But only five years ago, they didn’t even exist as a theory, much less in a lab.

Last year, two teams of physicists managed to actually create real time crystals in their labs. This physics breakthrough was remarkable, but wouldn’t have been possible without the theoretical work of Chetan Nayak, a physics professor at UC Santa Barbara and a researcher at Microsoft’s quantum lab, Station Q.

Time crystals were first theorized in 2012 by the Nobel Prize-winning physicist Frank Wilczek. As it happened, Nayak studied under Wilczek while pursuing his PhD in Princeton in the 1990s, but at this point time crystals weren’t even a gleam in Wilczek’s eye. The first time Nayak heard about them was almost 20 years later, when Wilczek bounced his time crystal theory off of him.

“Frank [Wilczek] was basically looking for a sanity check,” Nayak told me on the phone. “I had pretty mixed feelings about it. It sounded interesting and in many ways a very natural extrapolation from other things we know, but it also seemed to conflict with conventional wisdom.”

As it turned out, Wilczek’s theory about time crystals wasn’t correct. As Haruki Watanabe and Masaki Oshikawa, two researchers at the University of Tokyo demonstrated in a devastating proof in 2014, the time crystals envisioned by Wilczek were impossible. Nayak knew Oshikawa even before he helped arrange Nayak’s sabbatical in Tokyo in 2002 and described him to me as an “extremely careful and deep thinker.”

“When Masaki wrote this paper basically proving Wilczek’s paper was wrong, I knew that had to be taken pretty seriously,” Nayak told me. “So after that paper I wasn’t actively working on the time crystal idea at all. But in the process of working on something that seemed like a different problem—an apparently antithetical problem, really—the idea popped back.”

In 2016, Nayak and his colleagues published a paper that was essentially a blueprint for a time crystal. It corrected some erroneous assumptions in Wilczek’s original theory and seemed to be a viable model.

“I arranged a Skype meeting with Wilczek and Al Shapere, who had been a student of Frank’s about 10 years before me,” Nayak said. “I explained our paper to them, and both were really enthusiastic about it. That was a big encouragement.”

Less than a year later, Nayak and his colleagues’ modified time crystal theory was proven correct when researchers at the University of Maryland and Harvard used versions of the blueprint to make two different types of time crystals in their labs.

Since then, Nayak said he and his colleagues have been collaborating with the experimental physicists at the University of Maryland to continue to push the limits of what is possible with time crystals. For now, however, he said time crystals won’t have much use outside of an experimental lab setting.

Still, Nayak speculated that this physical oddity may one day provide the basis for a nearly perfect memory system for quantum computers and a host of other uses that can’t even be imagined yet.

“Any robust phenomena like a time crystal has a tendency to find applications, but you can't always guess what they're going to be in advance,” said Nayak, citing superconductivity as an example of another exotic physical phenomenon that only found widespread applications well after its realization in a lab. “These preliminary experiments look pretty promising. It feels like it’s the first chapter in a book that may have quite a few others.”