B A Time Crystal Visible to the Human Eye

[jedishrfu]

TL;DR Summary

Scientists demonstrate time crystal properties when light shines on them.

https://interestingengineering.com/science/worlds-first-time-crystal-visible-human-eye

University of Colorado Boulder physicists have created a “time crystal” visible to the human eye.

Nobel laureate Frank Wilczek first proposed the concept of a time crystal in 2012.

While other crystals, like diamonds, are defined by a repeating lattice pattern in space, a time crystal has a similarly organized structure but in the dimension of time. Its components wouldn’t sit still, but would move and transform in a never-ending cycle.

Although once believed to be impossible and a violation of a key law of thermodynamics, time crystals were first observed in a 2016 experiment.
...
A notable example occurred in 2021 when physicists used Google’s quantum computer to create a network of atoms that repeated their movements after being triggered by a laser.

This new creation is unique among them because it is the “world’s first” one to be visible to the human eye.

Zhao and his collaborator, Professor Ivan Smalyukh, used liquid crystals—the same materials found in phone displays—to achieve this feat.

The researchers filled glass cells with liquid crystals, which are rod-shaped molecules that exhibit solid and liquid properties.

Shining a specific light on the samples makes the liquid crystals move in repeating patterns.

 

[berkeman]

Interesting.

Although once believed to be impossible and a violation of a key law of thermodynamics,

Do you know which law of thermo they were saying this should violate?

 

[Filip Larsen]

Do you know which law of thermo they were saying this should violate?

Conservation of energy? Later: ah, it is probably a reference to the 2nd law: https://en.wikipedia.org/wiki/Time_crystal#Thermodynamics.

For example, both spatial and temporal pattern in classical dissipative reaction-diffusion systems requires an energy flux to emerge (due to the system being dissipative), so its tempting to think that a "crystaline" temporal pattern in a non-dissipative (Hamiltonian) system also requires some special non-linear effects (resonance couplings perhaps?) in order for the periodic solutions to be stable only for a special "resonant" set of periods while unstable for other periods. In chaotic systems the periodic solutions are dense, but that dictates nothing about their stability.

 

[berkeman]

Conservation of energy?

At least in their current embodiment, they use incident light energy to cause the movement in the liquid crystal solution, so it seems like conservation of energy would not be an issue (?).

 

[Filip Larsen]

it seems like conservation of energy would not be an issue

Sorry, 1st law was premature guess from my side. I updated my post to indicate 2nd instead :)

 

[berkeman]

Later: ah, it is probably a reference to the 2nd law: https://en.wikipedia.org/wiki/Time_crystal#Thermodynamics.

Thanks for the link, it was helpful.