I don't know anything about anything, but I want to enumerate some things I learned reading this article, and if someone actually knows what they're talking about and sees fit to take pity on me, please correct me so that I can understand what this actually means.
So a time crystal appears to be made up of real matter. The article mentions ions that are arranged in a certain particular way, cooled in order to reduce their energy, and this still makes sense so far.
So, the idea is to create a closed loop of sorts from a temporal perspective. I'm imagining an object as a set of states that the object can be observed in, and if there was a loop, it'd be possible to observe a certain sequence of states over and over.
The arrangement of the ions is important, and one of the properties is the spin, which is possible to change with a laser beam, because obviously.
Anyways, I guess the frequency of the oscillation of the ions changing spin, since they interact with each other in a domino fashion, can be controlled with the frequency of the laser.
They did this, and observed the ions changing in such a way where there was no driving influence and it's implied that the reason that this behavior was observed is because time symmetry was broken, which is just a fancy way of alleging that the universe is non-deterministic, I think.
Maybe this will eventually be useful?