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Ugh, that title though... WTH is a time crystal, and who decided to call it that? I'm not clicking the bait to find out.
by happyslobro 10y ago
Ugh, that title though... WTH is a time crystal, and who decided to call it that? I'm not clicking the bait to find out.
- schoen 10y agoApparently, it is serious physics and a totally new category of engineered physical system. So not clickbait.
- happyslobro 10y agoThanks for the heads up, sorry about the knee-jerk reaction.
- lscharen 10y agoThe core idea is not too strange, actually. A "normal" crystal has a repeating structure in space; a time crystal is a construct with a repeating temporal structure.
- ww520 10y agoI'm curious what does the temporal structure look like? Edit: have just looked it up. Looks like it's basically 3-D structure with repeated motion over time.
- radarsat1 10y agoDoes that mean it is continuously changing in a repetitive fashion?
- krapp 10y agoapparently yes, but because it's in a low energy state, it's impossible to extract any energy from it and do work (otherwise it would be a perpetual motion machine.)
- rbanffy 10y agoIt's interesting it is a perpetual motion machine, but it works only as long as you don't use it.
- krapp 10y agoThe universe has a perverse sense of humor.
- jacquesm 10y agoAny atomic nucleus with orbiting electrons fulfills that requirement, you could loosely call those time crystals too. Their half life for most stable atoms is so long that perpetual applies for most practical uses of the word. Which makes me wonder if these time crystals have a half-life too.
- marcosdumay 10y agoIt must be able to tunnel into some other structure. The half-life is defined by how much energy it needs to "melt" as the article says.
- cohomologo 10y agoElectrons do not orbit atomic nuclei in the quantum description of atoms. Instead, in the lowest energy state the electron wave function is spread out in a sphere around the nucleus, and this wave function stays constant in time. Almost all quantum systems do something like this in the ground state, which shows why the time crystal is something new and interesting.
- radarsat1 10y agoright, now i'll have to read the article to understand why there is no energy loss :) it does seem to be breaking some rules.. but I guess that's the achievement here. Intuitively there should be some concept of friction/heat loss but maybe on this scale things are different. Maybe it could be exploited as a battery? A way of capturing energy into a stable kinetic "state". (Like a flywheel..)
- gcr 10y agoCan any old oscillator be called a time crystal?
- oh_sigh 10y agoNo - oscillators need constant energy input in order to operate. Time crystals require no energy for temporal repetition.
- Dylan16807 10y agoThat's not really right. You can oscillate without constant energy input. Two particles can orbit forever. But normally that oscillation represents stored energy. They key to a time crystal is that it's oscillating while it's in a minimum energy state. It would take energy to make it stop moving.
- gcr 10y agoA pendulum in a vacuum will oscillate forever, requiring energy to stop. Is it like that?
- Dylan16807 10y agoIt requires force to stop. But you can output energy as you do so. Not so with these. They have 'no' energy despite movement.
- om2 10y agoDon't quantum harmonic oscillators oscillate even in their ground state? How is a time crystal different from a garden-variety QHO?
- cohomologo 10y agoNope. Like in the ground state of the hydrogen atom, the ground state of the quantum harmonic oscillator has the wave function spread out in a sphere, and this wave function stays constant in time. Almost all quantum systems do something like this in the ground state, which shows why the time crystal is something new and interesting.
- SilasX 10y agoSo ... like a regular wave?
- cfvergara 10y agohttps://en.wikipedia.org/wiki/Space-time_crystal https://en.wikipedia.org/wiki/Space-time_crystal