I do not understand time crystals because I do not understand why they are called time crystals. The substance (and its history and potential), which Marcia Wendorf expertly describes on the website Interesting Engineering, clearly has nothing to do with time as it has been understood since Arthur Eddington's 1928 book, The Nature of the Physical World.
A time crystal is an object that is comprised of a novel phase of matter and that moves in a regular, repeating cycle continuously and without using any energy. One of the discoverers of time crystals, Roderich Moessner, who is director of the Max Planck Institute for the Physics of Complex Systems in Dresden, Germany recently told Quanta Magazine, that with time crystals, "You evade the second law of thermodynamics." That's a pretty big deal!
A big deal? No, this changes just about everything.
And what's also amazing in all of this is people are now talking openly, normally, confidently about the perpetual motion machine, something that was until very recently (like last month) near the bottom of the rubbish bin of ideas.
Even the headline of Wendorf's post has no sense of shame whatsoever: "Google Claims It Created a New Phase of Matter That's In Perpetual Motion." And checkout the subheading of a post on Quanta Magazine: "Like a perpetual motion machine, a time crystal forever cycles between states without consuming energy. Physicists claim to have built this new phase of matter inside a quantum computer." But how can there be time in a substance whose changes are not permanent?
Recall that heartbreaking line from the once-popular Christian country tune, "One Day at a Time," written by Marijohn Wilkin and Kris Kristofferson:
Yesterday's gone, sweet Jesus
And tomorrow may never be mine
God help me today
Show me the way
One day at a time
In a word, the Charles I was yesterday is gone forever. And the Charles I am today will never be the same as the Charles I will become tomorrow. This is the way of all things caught in the pull of the cooling universe.
So why call a "time crystal" something that it isn't? Or why cause confusion? Time without time—is that time? Consider the key concept of the physicist who made the idea and the name of this timeless substance popular, Frank Wilczek: It is something in the universe that moves (or changes) without an input of energy. This means its "motion [can] continue indefinitely, just like a perpetual motion machine."
But how can you have time without entropy, the movement from order to disorder? How can you not feel its pull like these crystals which are "out-of-equilibrium" but still "stable"? How can you age? How can you recognize direction? We move from point A to point B (the former vanishing, the latter in transition), not point A to point A. What the physicists and the researchers at Google are talking about are timeless crystals. It is much closer to a Platonic substance than to a Heraclitian one.
So, as the presenter of Space Time Journal Club's 2017 "Time Crystals!" episode explains, the name of this "new state of matter" has more to do with marketing than a careful consideration of the meaning.
Let's end this post by giving this fifth phase of matter a new name: god crystals.
Why? Because that phrase comes close to what Plato called time in the strange cosmology of the Timaeus: "The moving image of eternity." According to Plato, god wanted to create a world that was close to his perfection, which is timeless or eternal. But how can you have things without time? So, god made eternity move. Sounds familiar? Yes, it does.
Also, Plato's description of time as a "moving eternity" is seriously flawed. It doesn't describe the experience of time at all—whereas Eddington's thermodynamic "arrow of time" does. (Eddington was an astronomer, a Quaker, and the one who verified a key feature of Einstein's theory of general relativity in 1919.) Plato describes, instead, the more possible condition of a god. The god in Timaeus is not describing how the universe was made but why it was made. Change in time can spring from change without time. But no change, meaning, no time, gives us nothing. If god is something, then it must be like these crystals that are getting a lot of attention on the internet. The god crystals.
From the Timaeus:
The father creator saw the creature which he had made moving and living, the created image of the eternal gods, he rejoiced, and in his joy determined to make the copy still more like the original; and as this was eternal, he sought to make the universe eternal, so far as might be. Now the nature of the ideal being was everlasting, but to bestow this attribute in its fullness upon a creature was impossible. Wherefore he resolved to have a moving image of eternity, and when he set in order the heaven, he made this image eternal but moving according to number, while eternity itself rests in unity; and this image we call time.