Perpetual Motion, maybe for real
April 30, 2013 4:39 PM Subscribe
Now, a technological advance has made it possible for physicists to test the idea. They plan to build a time crystal, not in the hope that this perpetuum mobile will generate an endless supply of energy (as inventors have striven in vain to do for more than a thousand years) but that it will yield a better theory of time itself.Nobel laureate Frank Wilczek's "somewhat embarassing" idea will be put to the test as scientists try to build time crystals.
This post was deleted for the following reason: Poster's Request -- Brandon Blatcher
Time crystals... sounds legit.
posted by 2bucksplus at 4:46 PM on April 30, 2013 [10 favorites]
posted by 2bucksplus at 4:46 PM on April 30, 2013 [10 favorites]
Not a actually a perpetual motion machine. The device does not provide any surplus energy.
posted by humanfont at 4:54 PM on April 30, 2013 [3 favorites]
posted by humanfont at 4:54 PM on April 30, 2013 [3 favorites]
Sounds very interesting. I always love when you get these theories where everyone is perfectly fine with the idea that they could be wrong, but let's test it and see. I did get a huge smile out of this line, too: an elaborate lab experiment, although it may take “anywhere between three and infinity years” to complete
Man - sure wish I could get my project plans approved with that level of specificity.
posted by It's Raining Florence Henderson at 4:54 PM on April 30, 2013 [3 favorites]
Man - sure wish I could get my project plans approved with that level of specificity.
posted by It's Raining Florence Henderson at 4:54 PM on April 30, 2013 [3 favorites]
Fleischmann and Pons could not be reached for comment.
posted by Cool Papa Bell at 4:58 PM on April 30, 2013 [2 favorites]
posted by Cool Papa Bell at 4:58 PM on April 30, 2013 [2 favorites]
No, not a double.
posted by justsomebodythatyouusedtoknow at 4:58 PM on April 30, 2013
posted by justsomebodythatyouusedtoknow at 4:58 PM on April 30, 2013
This is where we start to become Time Lords isn't it? Is it too early to pick out our goofy names yet? Perhaps something like "The Shipbreaker"
posted by edgeways at 5:02 PM on April 30, 2013
posted by edgeways at 5:02 PM on April 30, 2013
You guys see Primer?
posted by grobstein at 5:04 PM on April 30, 2013 [2 favorites]
posted by grobstein at 5:04 PM on April 30, 2013 [2 favorites]
These time crystals, they're smokable?
posted by Sys Rq at 5:05 PM on April 30, 2013 [8 favorites]
posted by Sys Rq at 5:05 PM on April 30, 2013 [8 favorites]
From the article: it may take “anywhere between three and infinity years” to complete
This is now going to be my standard estimate for all project completion times.
posted by mhum at 5:06 PM on April 30, 2013 [23 favorites]
This is now going to be my standard estimate for all project completion times.
posted by mhum at 5:06 PM on April 30, 2013 [23 favorites]
No, not a double.
Oh really oh okay my bad.
posted by (Arsenio) Hall and (Warren) Oates at 5:11 PM on April 30, 2013 [5 favorites]
Oh really oh okay my bad.
posted by (Arsenio) Hall and (Warren) Oates at 5:11 PM on April 30, 2013 [5 favorites]
Not a actually a perpetual motion machine. The device does not provide any surplus energy.
There's no requirement that it provides energy. First of all - this should be described as something weird - it definitely doesn't fall under the classical issues surrounding PMMs.
And second, even a standard crank-y PMM doesn't need to provide energy. It's a perpetual motion machine of the third kind - it stores energy but is exactly 100% efficient, no more no less.
posted by Lemurrhea at 5:22 PM on April 30, 2013 [1 favorite]
There's no requirement that it provides energy. First of all - this should be described as something weird - it definitely doesn't fall under the classical issues surrounding PMMs.
And second, even a standard crank-y PMM doesn't need to provide energy. It's a perpetual motion machine of the third kind - it stores energy but is exactly 100% efficient, no more no less.
posted by Lemurrhea at 5:22 PM on April 30, 2013 [1 favorite]
So if "perpetual motion machine" means "machine that produces energy from nothing," then yeah, this isn't a perpetual motion machine.
But it sounds like they're still describing something which
(i) moves back and forth
(ii) perpetually
(iii) without requiring energy from outside — because somehow, bizarrely, it isn't expending any energy.
Yes? I'm not trying to quibble, I'm just trying to understand what's going on.
posted by Now there are two. There are two _______. at 5:24 PM on April 30, 2013
But it sounds like they're still describing something which
(i) moves back and forth
(ii) perpetually
(iii) without requiring energy from outside — because somehow, bizarrely, it isn't expending any energy.
Yes? I'm not trying to quibble, I'm just trying to understand what's going on.
posted by Now there are two. There are two _______. at 5:24 PM on April 30, 2013
How can something move, and keep moving forever, without expending energy? It seemed an absurd idea — a major break from the accepted laws of physics.
Isn't that a common and well-known property of quantum systems, though?
The other thing I don't get is how it would be possible to measure a system like this without disrupting it. It seems like any measurement would necessarily involve an exchange of energy, and if energy is either entering or leaving the system, then the system cannot be at its ground state both before and after measurement.
posted by dephlogisticated at 5:25 PM on April 30, 2013
Isn't that a common and well-known property of quantum systems, though?
The other thing I don't get is how it would be possible to measure a system like this without disrupting it. It seems like any measurement would necessarily involve an exchange of energy, and if energy is either entering or leaving the system, then the system cannot be at its ground state both before and after measurement.
posted by dephlogisticated at 5:25 PM on April 30, 2013
This is where we start to become Time Lords isn't it? Is it too early to pick out our goofy names yet? Perhaps something like "The Shipbreaker"
I'm getting in early on this one. When they were giving out hip hop names, by the time my turn came up, all the good names were taken.
That's why down at the club they call me Asparagus P.
posted by ZenMasterThis at 5:37 PM on April 30, 2013 [3 favorites]
I'm getting in early on this one. When they were giving out hip hop names, by the time my turn came up, all the good names were taken.
That's why down at the club they call me Asparagus P.
posted by ZenMasterThis at 5:37 PM on April 30, 2013 [3 favorites]
The other thing I don't get is how it would be possible to measure a system like this without disrupting it.I think that's the thrust of the final criticism by Bruno: their plan for measurement does involve definitely putting one of the 100 ions in a non-ground state, so whatever they see, they are not seeing something that happens to 100 items all in their ground state.
posted by jepler at 5:38 PM on April 30, 2013
It's Newton's first law is what it is.How can something move, and keep moving forever, without expending energy? It seemed an absurd idea — a major break from the accepted laws of physics.Isn't that a common and well-known property of quantum systems, though?
I know that's not it is referring to, but that quote struck me as an incredibly poor phrasing for a science news article.
posted by Flunkie at 5:40 PM on April 30, 2013 [3 favorites]
I could imagine this working as some type of carbon nanocircuit embedded in fancy quartz.
I'm basing my judgment on the maturity of methods in molecular mechanics for carbon compounds, combined with the utility of quartz as a reliable oscillator.
You might be able to perform a quantum simulation of finite state machines in that type of system.
At the very least, I would prefer to keep my schedule punctual according to the whims of...
Time Crystals!
cue mad science music
>Next, the researchers will switch on a static magnetic field in the trap, which their theory says should induce the ions to start rotating (and continue doing so indefinitely). If all goes as planned, the ions will cycle around to their starting point at fixed intervals, forming a regularly repeating lattice in time that breaks temporal symmetry.
This strikes me as similar to the electron resonance in aromatic compounds
posted by MisplaceDisgrace at 5:49 PM on April 30, 2013
I'm basing my judgment on the maturity of methods in molecular mechanics for carbon compounds, combined with the utility of quartz as a reliable oscillator.
You might be able to perform a quantum simulation of finite state machines in that type of system.
At the very least, I would prefer to keep my schedule punctual according to the whims of...
Time Crystals!
cue mad science music
>Next, the researchers will switch on a static magnetic field in the trap, which their theory says should induce the ions to start rotating (and continue doing so indefinitely). If all goes as planned, the ions will cycle around to their starting point at fixed intervals, forming a regularly repeating lattice in time that breaks temporal symmetry.
This strikes me as similar to the electron resonance in aromatic compounds
posted by MisplaceDisgrace at 5:49 PM on April 30, 2013
The Doctor: Of course! It's time crystals! Why didn't I think of this earlier?
Amy: (deadpan) Time crystals.
The Doctor: Yeah, but not like in a wristwatch. These are like spatial crystals--which you call crystals--but instead of the atoms being regularly arranged in space, they're regularly arranged in time!
Amy: ...
The Doctor: See, they're perfectly stable, no decay, just like a crystal. But only if you're looking at the right . . . moments.
posted by General Tonic at 5:53 PM on April 30, 2013 [15 favorites]
Amy: (deadpan) Time crystals.
The Doctor: Yeah, but not like in a wristwatch. These are like spatial crystals--which you call crystals--but instead of the atoms being regularly arranged in space, they're regularly arranged in time!
Amy: ...
The Doctor: See, they're perfectly stable, no decay, just like a crystal. But only if you're looking at the right . . . moments.
posted by General Tonic at 5:53 PM on April 30, 2013 [15 favorites]
I have been wanting to make a pun like that since I started learning upper level statistics.
posted by MisplaceDisgrace at 5:55 PM on April 30, 2013 [1 favorite]
posted by MisplaceDisgrace at 5:55 PM on April 30, 2013 [1 favorite]
We've replaced his regular coffee with Folger's time crystals. Let's see if he notices the basic breakdown in causality.
posted by klangklangston at 5:56 PM on April 30, 2013 [40 favorites]
posted by klangklangston at 5:56 PM on April 30, 2013 [40 favorites]
Next, the researchers will switch on a static magnetic field in the trap, which their theory says should induce the ions to start rotating (and continue doing so indefinitely). If all goes as planned, the ions will cycle around to their starting point at fixed intervals, forming a regularly repeating lattice in time that breaks temporal symmetry.
Aren't they putting energy into the system by maintaining a magnetic field? Are there any physicists who understand this well enough to explain the expected phenomenon to a layperson?
posted by Blazecock Pileon at 5:57 PM on April 30, 2013 [1 favorite]
Aren't they putting energy into the system by maintaining a magnetic field? Are there any physicists who understand this well enough to explain the expected phenomenon to a layperson?
posted by Blazecock Pileon at 5:57 PM on April 30, 2013 [1 favorite]
The kicker isn't even the "perpetual motion" aspect.
If Wilczek's crazy idea works, it may be a bridge between relativity and quantum mechanics.
posted by General Tonic at 5:57 PM on April 30, 2013 [3 favorites]
If Wilczek's crazy idea works, it may be a bridge between relativity and quantum mechanics.
posted by General Tonic at 5:57 PM on April 30, 2013 [3 favorites]
Five more infinity gems to go.
posted by painquale at 6:00 PM on April 30, 2013 [4 favorites]
posted by painquale at 6:00 PM on April 30, 2013 [4 favorites]
>Aren't they putting energy into the system by maintaining a magnetic field?
You can also use magnets to cool things down.
posted by MisplaceDisgrace at 6:02 PM on April 30, 2013
You can also use magnets to cool things down.
posted by MisplaceDisgrace at 6:02 PM on April 30, 2013
Sys Rq: "These time crystals, they're smokable?"
Dilational Matrix of Temporality Crystals is the full term for them.
posted by symbioid at 6:02 PM on April 30, 2013 [1 favorite]
Dilational Matrix of Temporality Crystals is the full term for them.
posted by symbioid at 6:02 PM on April 30, 2013 [1 favorite]
All you need to do to build a "perpetual" motion machine is build an aggregator that will collect energy from future timeframes as they dump energy trying to enter your timeframe. You don't need to build anything as complex as a receptor that can decrypt, parse and reassemble transmissions from the future -- just accumulate the massive amount of energy that future time travellers are dispensing trying to travel back to your time.
They'll interpret any failure of time travellers to return as "oh, hey, time travel. Dinosaurs." and no worries! Your energy issues will be 100% resolved until the point that you invent time travel, at which point you're fucked, but that's the future's problem, right?
posted by Shepherd at 6:07 PM on April 30, 2013 [5 favorites]
They'll interpret any failure of time travellers to return as "oh, hey, time travel. Dinosaurs." and no worries! Your energy issues will be 100% resolved until the point that you invent time travel, at which point you're fucked, but that's the future's problem, right?
posted by Shepherd at 6:07 PM on April 30, 2013 [5 favorites]
hey guys, what's going on in here?
o.0'
(backs out slowly. closes door quietly. runs away very quickly)
posted by physicsmatt at 6:10 PM on April 30, 2013 [15 favorites]
o.0'
(backs out slowly. closes door quietly. runs away very quickly)
posted by physicsmatt at 6:10 PM on April 30, 2013 [15 favorites]
Cool! I saw something about this on some sciency blog a few months ago and figured it was at best some sort of untestable theoretical concept at best (and crackpottery at worst.) Although it does remind me of Dr. Dinosaur explaining to Atomic Robo that he can too do time travel, because CRYSTALS.
posted by gamera at 6:19 PM on April 30, 2013 [2 favorites]
posted by gamera at 6:19 PM on April 30, 2013 [2 favorites]
Time Crystal sounds like a c-list Jim Henson movie.
posted by nathancaswell at 6:20 PM on April 30, 2013 [1 favorite]
posted by nathancaswell at 6:20 PM on April 30, 2013 [1 favorite]
I'm going to show my ignorance here.
What's the difference between this and a really cold rotating ring, or is a rotating ring a time crystal?
I think this is the passage I'm having trouble with: Eventually, his equations indicated that atoms could indeed form a regularly repeating lattice in time, returning to their initial arrangement only after discrete (rather than continuous) intervals, thereby breaking time symmetry.
posted by cosmic.osmo at 6:44 PM on April 30, 2013
What's the difference between this and a really cold rotating ring, or is a rotating ring a time crystal?
I think this is the passage I'm having trouble with: Eventually, his equations indicated that atoms could indeed form a regularly repeating lattice in time, returning to their initial arrangement only after discrete (rather than continuous) intervals, thereby breaking time symmetry.
posted by cosmic.osmo at 6:44 PM on April 30, 2013
If anyone is curious, you can find the papers here. Also, just to show how wrong-headed that "Pathology Physics" thread was, he's also interested in fundamental constants.
Who knows, maybe there's something to brutinos...
posted by ennui.bz at 6:46 PM on April 30, 2013
Who knows, maybe there's something to brutinos...
posted by ennui.bz at 6:46 PM on April 30, 2013
Can someone explain this in small words to those of us who didn't take physics? Seriously, Homer Simpson words.
posted by Ghostride The Whip at 7:00 PM on April 30, 2013 [1 favorite]
posted by Ghostride The Whip at 7:00 PM on April 30, 2013 [1 favorite]
Marge: I'm worried about the kids, Homey. Lisa's becoming very
obsessive. This morning I caught her trying to dissect her own
raincoat.
Homer: [scoffs] I know. And this perpetual motion machine she made
today is a joke! It just keeps going faster and faster.
Marge: And Bart isn't doing very well either. He needs boundaries and
structure. There's something about flying a kite at night that's
so unwholesome. [looks out window]
Bart: [creepy voice] Hello, Mother dear.
Marge: [closing the curtains] That's it: we have to get them back to
school.
Homer: I'm with you, Marge. Lisa! Get in here.
[Lisa walks in, chuckling nervously]
In this house, we obey the laws of thermodynamics!
posted by 445supermag at 7:08 PM on April 30, 2013 [3 favorites]
obsessive. This morning I caught her trying to dissect her own
raincoat.
Homer: [scoffs] I know. And this perpetual motion machine she made
today is a joke! It just keeps going faster and faster.
Marge: And Bart isn't doing very well either. He needs boundaries and
structure. There's something about flying a kite at night that's
so unwholesome. [looks out window]
Bart: [creepy voice] Hello, Mother dear.
Marge: [closing the curtains] That's it: we have to get them back to
school.
Homer: I'm with you, Marge. Lisa! Get in here.
[Lisa walks in, chuckling nervously]
In this house, we obey the laws of thermodynamics!
posted by 445supermag at 7:08 PM on April 30, 2013 [3 favorites]
What's the difference between this and a really cold rotating ring, or is a rotating ring a time crystal?
A really cold rotating ring is a time crystal, if the atoms align only at discrete times. Just like a group of atoms is a regular (spatial) crystal if the atom only occupy certain spaces in a lattice.
posted by 445supermag at 7:14 PM on April 30, 2013 [1 favorite]
A really cold rotating ring is a time crystal, if the atoms align only at discrete times. Just like a group of atoms is a regular (spatial) crystal if the atom only occupy certain spaces in a lattice.
posted by 445supermag at 7:14 PM on April 30, 2013 [1 favorite]
Time-symmetry is what causes the principle of conservation of energy. If that symmetry is broken, energy isn't conserved.
(the expansion of the universe already breaks time symmetry, fwiw)
posted by empath at 7:14 PM on April 30, 2013
(the expansion of the universe already breaks time symmetry, fwiw)
posted by empath at 7:14 PM on April 30, 2013
When it breaks and chronitons spill out causing time skips, let's just hope they have Bubblegum Tate on speed-dial.
posted by mrgoat at 7:14 PM on April 30, 2013 [2 favorites]
posted by mrgoat at 7:14 PM on April 30, 2013 [2 favorites]
I was thinking more like an episode of Fringe.
Can't you just hear John Noble saying "time crystals"
posted by 2bucksplus at 8:10 PM on April 30, 2013 [4 favorites]
Can't you just hear John Noble saying "time crystals"
posted by 2bucksplus at 8:10 PM on April 30, 2013 [4 favorites]
The article is not clear on why this is interesting. I'll try to explain it as simply as I can.
Any moving (or rotating) particle contains kinetic energy. Once it's started moving, it doesn't take any energy to keep moving indefinitely (assuming no friction or air resistance, etc). That's just inertia. (A body in motion stays in motion).
So the fact that this thing rotates indefinitely isn't the interesting part. The interesting thing here is that this crystal is at it's lowest possible energy state, and yet it is still rotating.
posted by empath at 8:16 PM on April 30, 2013 [2 favorites]
Any moving (or rotating) particle contains kinetic energy. Once it's started moving, it doesn't take any energy to keep moving indefinitely (assuming no friction or air resistance, etc). That's just inertia. (A body in motion stays in motion).
So the fact that this thing rotates indefinitely isn't the interesting part. The interesting thing here is that this crystal is at it's lowest possible energy state, and yet it is still rotating.
posted by empath at 8:16 PM on April 30, 2013 [2 favorites]
And I guess the controversy here is over whether this crystal is actually in its lowest possible energy state, or whether it would be possible to remove energy from the system to make it stop.
posted by empath at 8:18 PM on April 30, 2013
posted by empath at 8:18 PM on April 30, 2013
The other thing I don't get is how it would be possible to measure a system like this without disrupting it. It seems like any measurement would necessarily involve an exchange of energy, and if energy is either entering or leaving the system, then the system cannot be at its ground state both before and after measurement.
They could just cool it back to the ground state after measuring it, yeah?
posted by empath at 8:20 PM on April 30, 2013
They could just cool it back to the ground state after measuring it, yeah?
posted by empath at 8:20 PM on April 30, 2013
Thanks, empath!
posted by Ghostride The Whip at 8:25 PM on April 30, 2013
posted by Ghostride The Whip at 8:25 PM on April 30, 2013
So basically it's Conway's Life, but with calcium atoms? You know, like when the field settles down and mostly you just have little 2x2 blocks and such, but here and there you get a 1x3 flasher that just keeps going back and forth forever? Life imitating cellular automata?
posted by Scientist at 8:37 PM on April 30, 2013
posted by Scientist at 8:37 PM on April 30, 2013
Would such a device necessarily by accurate (in time) to an arbitrary degree? Say, more accurate than existing timekeeping methods used in spacecraft, I wonder?
posted by newdaddy at 8:46 PM on April 30, 2013
posted by newdaddy at 8:46 PM on April 30, 2013
These time crystals, they're smokable?
No. Only time-crystal meth.
posted by sexyrobot at 9:19 PM on April 30, 2013
No. Only time-crystal meth.
posted by sexyrobot at 9:19 PM on April 30, 2013
(it seems i retroactively never made my time travel 'double' joke :( )
posted by Anything at 9:54 PM on April 30, 2013
posted by Anything at 9:54 PM on April 30, 2013
I no nothing of these quantum things, but my guess is that the problem is with the word 'move'. The article says that its state is time dependent. I think that it is not so much moving, as existing in different states at different times, thus giving the appearance of movement.
posted by eye of newt at 11:07 PM on April 30, 2013
posted by eye of newt at 11:07 PM on April 30, 2013
State includes position, and we're talking about atoms here, so the uncertainty is fairly small compared to an electron, so if they're saying they are moving, then they are moving.
posted by empath at 11:18 PM on April 30, 2013
posted by empath at 11:18 PM on April 30, 2013
@(Arsenio) Hall and (Warren) Oates:
Were you saying that Frank Wilczek is a crank? Maybe as a joke? Or were you unaware of his credentials?
posted by lastobelus at 11:32 PM on April 30, 2013
Were you saying that Frank Wilczek is a crank? Maybe as a joke? Or were you unaware of his credentials?
posted by lastobelus at 11:32 PM on April 30, 2013
The key to interstellar travel is convincing the universe the ship you're on exists sequentially in multiple locations in space-time.
And getting off at the right stop.
(A "crystal ship" if you will.)
posted by bigbigdog at 11:43 PM on April 30, 2013
And getting off at the right stop.
(A "crystal ship" if you will.)
posted by bigbigdog at 11:43 PM on April 30, 2013
lastobelus: I don't think Wilczek is a crank, but it's perfectly possible to be a crank while having impressive credentials. I can certainly think of a Nobel Prize winning physicist with some views I find distinctly strange.
posted by edd at 5:19 AM on May 1, 2013 [1 favorite]
posted by edd at 5:19 AM on May 1, 2013 [1 favorite]
If all goes as planned, the ions will cycle around to their starting point at fixed intervals, forming a regularly repeating lattice in time that breaks temporal symmetry.
Can anyone who knows something about physics translate this out of "journalist" and into "coherent"?
First of all I thought time was already asymmetric (thermodynamics and all that). Second I don't understand how a rotating ring of ions would "break time symmetry" or why that would be significant?
posted by ook at 5:27 AM on May 1, 2013
Can anyone who knows something about physics translate this out of "journalist" and into "coherent"?
First of all I thought time was already asymmetric (thermodynamics and all that). Second I don't understand how a rotating ring of ions would "break time symmetry" or why that would be significant?
posted by ook at 5:27 AM on May 1, 2013
Time is asymmetric under reversal on certain scales in physics because of the initial state of low entropy and the expansion of the universe, but at small scales, it's symmetrical, but that's not really what they're they're talking about here. There are continuous symmetries and discrete symmetries. Time reversal is discrete, time translation is continuous.
One thing you need to know about is Noether's theorem which states that symmetries in physical equations create conserved quantities in physics (and all conserved quantities are created by symmetries).
As an example, consider the fact that if you perform an experiment in empty space, and then move it some distance away and recreate the conditions, you'll get the same results. The result of that symmetry happens to be the conservation of momentum. The fact that you can get the same result from a different angle results in conservation of angular momentum.
Now, imagine performing an experiment in orbit with a thrown projectile, and then performing it again from much further away. You don't get the same result. That's because the gravitational field breaks spatial symmetry-- it has a different value at a different point in space.
Time translation symmetry-- the fact that if you do the exact same experiment only separated by an interval of time, you will get the same results (or alternatively, that the laws of physics don't change over time) creates the conservation of energy.
Which essentially means that if you have a system which is neither receiving nor expending energy, that every time you measure the energy of a system it will be the same.
This time crystal, on the other hand, will theoretically return a different value for the energy every time you measure it, in a repeating cycle, which means that energy is not being conserved, and that for some reason time symmetry has been broken in the system.
Disclaimer: I am not a physicist. If physics Matt shows up he might explain it better or tell me I am wrong.
posted by empath at 6:41 AM on May 1, 2013 [5 favorites]
One thing you need to know about is Noether's theorem which states that symmetries in physical equations create conserved quantities in physics (and all conserved quantities are created by symmetries).
As an example, consider the fact that if you perform an experiment in empty space, and then move it some distance away and recreate the conditions, you'll get the same results. The result of that symmetry happens to be the conservation of momentum. The fact that you can get the same result from a different angle results in conservation of angular momentum.
Now, imagine performing an experiment in orbit with a thrown projectile, and then performing it again from much further away. You don't get the same result. That's because the gravitational field breaks spatial symmetry-- it has a different value at a different point in space.
Time translation symmetry-- the fact that if you do the exact same experiment only separated by an interval of time, you will get the same results (or alternatively, that the laws of physics don't change over time) creates the conservation of energy.
Which essentially means that if you have a system which is neither receiving nor expending energy, that every time you measure the energy of a system it will be the same.
This time crystal, on the other hand, will theoretically return a different value for the energy every time you measure it, in a repeating cycle, which means that energy is not being conserved, and that for some reason time symmetry has been broken in the system.
Disclaimer: I am not a physicist. If physics Matt shows up he might explain it better or tell me I am wrong.
posted by empath at 6:41 AM on May 1, 2013 [5 favorites]
I tried reading the article but I had to stop halfway through, because no matter how hard I tried to parse it, I couldn't understand it. Then I tried reading it with The Final Countdown playing in the background, and while I still didn't understand anything, I believe I have seen the future.
posted by Mchelly at 7:09 AM on May 1, 2013 [1 favorite]
posted by Mchelly at 7:09 AM on May 1, 2013 [1 favorite]
This time crystal, on the other hand, will theoretically return a different value for the energy every time you measure it, in a repeating cycle, which means that energy is not being conserved, and that for some reason time symmetry has been broken in the system.
I don't understand it very well at all, but I don't think this is right. I think it has the same energy throughout, and anyway just because a system breaks a symmetry doesn't mean that there is some violation of the laws involved which are symmetric, and which give rise to the conserved quantity.
posted by edd at 7:52 AM on May 1, 2013 [1 favorite]
I don't understand it very well at all, but I don't think this is right. I think it has the same energy throughout, and anyway just because a system breaks a symmetry doesn't mean that there is some violation of the laws involved which are symmetric, and which give rise to the conserved quantity.
posted by edd at 7:52 AM on May 1, 2013 [1 favorite]
Shurely all the energy needed to cool these things down and keep them at just above freezing is inputting energy in a way? Also, its a bit useless if you need to expend tons of cooling energy to get a microscopic PMM.
posted by marienbad at 8:53 AM on May 1, 2013
posted by marienbad at 8:53 AM on May 1, 2013
No, broken symmetries do not violate any laws. Broken symmetries in nature are basically what allow anything interesting to exist at all, otherwise all we would have is massless particles zipping around at light speed. This is just a new one. But they do mean that quantities that are normally preserved are not preserved in the system for which the symmetry is broken.
posted by empath at 9:25 AM on May 1, 2013
posted by empath at 9:25 AM on May 1, 2013
If that were the case then when a normal crystal forms and breaks spatial symmetry what do you think goes on with respect to its momentum and angular momentum?
posted by edd at 10:39 AM on May 1, 2013 [1 favorite]
posted by edd at 10:39 AM on May 1, 2013 [1 favorite]
There's no momentum, because the spatial symmetry group in a crystal is discrete, not continuous. You have quasi particles like phonons, etc, instead of particles freely moving in space. That's the difference between a gas and a solid, basically.
posted by empath at 4:14 PM on May 1, 2013
posted by empath at 4:14 PM on May 1, 2013
Which isn't to say that if you pick a crystal up and throw it that it doesn't have momentum, it's only inside the crystal on an atomic scale that symmetry is broken.
posted by empath at 4:16 PM on May 1, 2013
posted by empath at 4:16 PM on May 1, 2013
Man, when the tarot card/crystals-have-energy idiots hear about this....
posted by marienbad at 4:19 PM on May 1, 2013 [1 favorite]
posted by marienbad at 4:19 PM on May 1, 2013 [1 favorite]
And the symmetry in a time crystal is supposed to be discrete too, no? That's why they called it a crystal?
posted by edd at 11:37 PM on May 1, 2013
posted by edd at 11:37 PM on May 1, 2013
Right. I'm not exactly clear on how that part of it works, tbh. But that's the general idea. Instead of a continuous translational symmetry in time, you have a discrete symmetry, so that you get the same results if you check at particular moments in time, but not others, which is what causes the cyclical changes. But that's where you kind of have to look at the equations, and those are way beyond my math skills.
posted by empath at 11:47 PM on May 1, 2013
posted by empath at 11:47 PM on May 1, 2013
The paper clearly refers to the states of the time crystal as energetically degenerate. When you observe it in one of those states it's at the same energy as when it's in any of the other states, but it can still be distinguished by other observables. It does not "return a different value for the energy every time you measure it".
posted by edd at 3:57 AM on May 2, 2013
posted by edd at 3:57 AM on May 2, 2013
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posted by It's Raining Florence Henderson at 4:44 PM on April 30, 2013 [6 favorites]