Time crystals are matter made of particles that oscillate in steady, repeating cycles. Scientists predicted them theoretically before confirming their existence roughly a decade ago. No practical applications have been commercialized yet, but they are considered promising for quantum computing and advanced data storage.
Physicists at New York University have now built a new kind — one that appears to violate Newton’s Third Law of Motion.
The setup is deliberately simple: tiny styrofoam beads, similar to packing material, suspended in mid-air by sound waves. According to the announcement, the entire device stands about one foot tall and can be held in one hand. The results were published in Physical Review Letters.
The beads interact by scattering sound waves between one another. Larger beads scatter more sound than smaller ones, which means a large bead exerts a stronger force on a smaller bead than the smaller bead exerts in return. That imbalance is the key. Newton’s Third Law requires forces to occur in equal and opposite pairs — these do not. The interactions are nonreciprocal, and the law does not apply because the forces are carried by sound waves rather than direct contact between the particles.
“Think of two ferries of different sizes approaching a dock,” said Mia Morrell, an NYU graduate student and co-author. “Each one makes water waves that pushes the other one around — but to different degrees, depending on their size.”
Because the forces are uneven, the beads begin oscillating spontaneously while suspended, producing the repeating rhythm that defines a time crystal.
Visible to the Naked Eye
Most time crystal experiments require highly controlled laboratory conditions and cannot be observed directly. This one can. David Grier, professor of physics and director of NYU’s Center for Soft Matter Research, describes it as “incredibly simple” for a system that produces such complex behavior.
“Time crystals are fascinating not only because of the possibilities, but also because they seem so exotic and complicated,” Grier said. “Our system is remarkable because it’s incredibly simple.”
A Window Into Biological Timing
The research, also co-authored by NYU undergraduate Leela Elliott, carries a secondary implication beyond physics and computing. Some biochemical processes in the human body involve nonreciprocal interactions — including how the body breaks down food. The study says this time crystal system could help scientists better understand biological timing mechanisms such as circadian rhythms, which operate on similar principles.
The work was supported by grants from the National Science Foundation under awards DMR-2104383 and DMR-2428983.
Photo by Pixabay
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