What is a time crystal?
In: Planetary Science
A normal crystal is a repeating pattern in 1, 2, or 3 spatial dimensions. A salt crystal, for example, consists of alternating sodium and chloride ions in a 3-D matrix. A time crystal extends this repeating pattern into the fourth dimension, time.
Now, a wristwatch ticking the seconds is not a time crystal because there is energy being placed into the system from its battery. For a time crystal to be considered valid, it has to repeat its pattern *without* external input. Needless to day, that’s very difficult to achieve, though the longest sustained time crystal has lasted about 40 minutes, which is pretty good.
A normal crystal (space crystal) has a repeating structure in space.
A time crystal has a repeating structure in time. For example, it could repeat between structures A, B, and C in the same pattern over and over again after the same amount of time.
A spacetime crystal is also a thing. It has a repeating structure in both space and time. Structures A, B, and C would just be repeating structures in space, and the crystal changes between them like a time crystal would.
I don’t understand any of this. Are time crystals real?
A space crystal oscillates (alternates) between multiple structures. So essentially the structure repeats in time.
Like taking a live photo with your iPhone and looping it with “bounce”.
It’s a substance whose normal resting state is oscillating back and forth between multiple states. It’s not unusual for things to oscillate back and forth, but it is very unusual for that to be their resting state.
Although, it’s not exactly a resting state, since they have to shoot a substance with a laser to create one. I don’t understand the details of why physicists consider it a resting state.
It’s also the coolest name for the most underwhelming thing in physics.
Toss a bunch of marbles into a bowl of water and they’ll bump and jostle their way to the bottom. Eventually they’ll all settle down into an unmoving state. This is their *resting state*, and it represents the point at which they have the least amount of energy. If you want them to move around any more you have to add energy back into the system (by, say, shaking the bowl around).
But imagine if I’m that lowest energy state they were still moving. Let’s say they continue to swirl around the bottom of the bowl. They’re at the lowest possible energy they could have but they’re still moving. Obviously, marbles in a bowl of water *don’t* do this so it can be difficult to picture, but that’s basically what a time crystal is: a system where its lowest energy state is still moving.
It’s a little more specific than that though, which is where the “crystal” part comes in. We define a (spatial) crystal as a structure that repeats in space: take any one part of the structure and you’ll be able to find identical parts at regular intervals in any direction within the structure. A time crystal, by analogy, exhibits the same repeating behavior. Instead of repeating in space though, it repeats in time. So that still-moving lowest energy state? The same arrangement of the system will occur time after time. If you take a snapshot of it any given moment you’ll be able to find it in that same arrangement at a regular interval in time. Usually this interval is measured in something like microseconds.
Now it should be noted that we’ve never created a time crystal that doesn’t involve *some* input of energy (i.e., shaking up the bowl) but we have created ones that continue oscillating for much longer than we’d expect for the energy put in. Most recently something like 40 seconds off a pretty weak laser pulse.
So what use are they? No idea! They’re a new thing to play with and physicists are still trying to figure out what to do with them. It’s pretty common in physics—and science in general—for things that eventually become important to not have any immediately obvious uses.
None of the responses here summarize simply enough for me to understand. But even upon trying to look it up and learn myself, nothing still made much sense to me.
Alas, I asked ChatGPT because it was the only thing that helped me wrap my head around it. Here’s what it says:
>Time crystals don’t have a physical appearance like traditional crystals that you can see or touch. Since they are a concept in the world of physics, you can think of them more like a unique dance or behavior that certain materials exhibit at the tiniest, atomic level. So, they don’t have a visual appearance in the way you might picture a gemstone or crystal.
>Think of a time crystal as a never-ending dance party for particles. Imagine you have a bunch of friends who love to dance, and they always follow a pattern. Now, a time crystal is like having these friends dance in a way that never repeats exactly the same, but it still follows a special order that scientists find fascinating. It’s like having a forever-changing dance that keeps surprising everyone!
>Time crystals are not something you find around like regular crystals. They are created in laboratories by scientists using special materials and equipment. They are important because they challenge our understanding of time and the way things behave. Scientists study time crystals to learn more about the fundamental rules of the universe, opening the door to new discoveries in physics and technology.
>They are called time crystals because they exhibit a special property related to time. Unlike regular crystals that have repeating patterns in space, time crystals have repeating patterns in time. It’s like they have a dance routine that keeps going without ever stopping, creating a connection to the concept of time. So, the name “time crystals” captures their unique behavior involving the dimension of time.
A normal crystal has a repeating molecular structure. The pattern that it’s made of repeats over and over through the space that the object occupies.
A time crystal has a repeating structure through time. This basically means that it’s structure is flip-flopping between two or more states.
Yes, time crystals are real, some scientists managed to make one a few years ago. It was a tiny piece of “indium gallium arsenide doped with silicon” that they shot with a laser and the arrangement of the atoms went back and forth between a few states for a little less than an hour before stopping.
Ignore the words time crystal for a second. It’s almost misleading to laymen.
Imagine a clock that’s ticking with a dead battery, but it somehow is still ticking in repeating patterns.
You realize, you cannot take any energy out of the watch’s battery. As a dead battery, the watch simply still ticks.
A time crystal is like that. It’s a tiny little structure at its lowest energy state, that moves in a repeating pattern at exact intervals.
Idk, maybe you could make a very accurate watch out of one instead of relying on the atomic watches in space?
Not sure how it’s useful but it simply sounds cooler than it is.
Like imagine calling a clock, a space-time machine bc it can tell the time. Just sounds misleading
I’ll handle this one!
A time crystal is something I never heard of until people started asking what it is weekly on this sub.
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