Scientists have created a "time crystal" that floats in the air
Physicists from New York University (NYU) reported that they have discovered a new kind of time crystal - a system that itself begins to move in a strictly repetitive rhythm, as if "ticking".
The main difference of this version is that it can be seen without instruments: the experiment used small balls that hang in the air due to sound.
The scientists took lightweight foam beads (like from packaging material) and placed them in a device that creates a standing sound wave. Such a wave can hold light objects in the air - the result is a "sound cushion".
The most interesting thing began when beads of different sizes were placed next to each other. They began to influence each other not directly, but through sound: each bead scatters sound waves, and these waves push the neighbouring one.
But the pushes are unequal: a large bead "pushes" a small bead more strongly than a small bead pushes a large bead. That is, the interaction is asymmetrical. Because of this, a pair of beads can go to the mode of stable oscillations and "beat" the rhythm - so there is a crystal of time in this simple, "visible" system.
The authors note that such effects can help to better understand systems where participants influence each other in different ways - both in physics and in more complex processes (for example, in biological chains).