Time crystals could behave almost like perpetual motion machines

Feb 20, 2012 by Lisa Zyga report
time
Image by Sam Rohn, flickr.com/photos/nylocations/

(PhysOrg.com) -- As every young science student knows, moving objects have kinetic energy. But just how much energy does something need to move? In a new study, a pair of physicists has shown that it’s theoretically possible for a system in its lowest energy state, or ground state, to exhibit periodic motion. This periodically moving system can be thought of as the temporal equivalent of a crystal, which is defined by its spatial periodicity. What’s even more intriguing about these "time crystals" is that, by exhibiting motion at their state of lowest energy, they break a fundamental symmetry called time translation symmetry and become "perilously close" to looking like perpetual motion machines.

The physicists, Frank Wilczek of MIT (a 2004 Nobel Laureate) and Alfred Shapere of the University of Kentucky, have posted two papers on their novel idea of time crystals at arXiv.org. One paper focuses on classical time crystals, while the other looks at quantum time crystals.

Modern physics deals with many types of symmetry, but one of the most fundamental is time translation symmetry, which basically says that the laws of physics we have today should still be here tomorrow. Likewise, if a system’s features remain constant over time, that system obeys time translation symmetry. On the other hand, a clock, which has hands that are constantly moving, breaks time translation symmetry.

But while a clock requires a power source to break this symmetry, a system in its lowest energy state has no power source by definition. To show that such a system can indeed exhibit motion, Wilczek and Shapere performed some complex mathematical calculations, which revealed that a system in its lowest energy state could move in a periodic motion, such as a loop or orbit. As far as the scientists know, this is the first time that a system in its lowest without any external source of power has been shown to exhibit motion and break time translation symmetry.

As the physicists explained, this discovery doesn’t mean that such systems actually exist in nature, but that they can exist. At first, the were somewhat doubtful that they could exist at all, since such a system would behave very similar to a perpetual motion machine, the fantasy device that could run forever with no energy input. However, building such a system may actually be less improbable than showing that it can simply exist. As the scientists noted, under the right circumstances, a superconductor almost acts in this manner because ground-state electrons can continuously loop through it.

“It’s so tricky to implement mathematically,” Wilczek told PhysOrg.com. “It’s surprising that they can exist at all. But, whether or not they exist naturally, I’m very optimistic that it’s something one could engineer.”

He added that, even though time crystals might move continuously, they couldn’t be used to generate useful energy since they can’t be disturbed, and they wouldn’t violate the second law of thermodynamics. Nevertheless, the possibilities for time crystals are exciting, and the scientists plan to investigate them further in the future.

“There are many directions to go here,” Wilczek said. “The question is what to do first. ... One question is how this kind of idea might be realized in actual materials. What are the materials, how can we tell that it’s happening, what dimensions do the materials have? If this is a state of matter that’s different from other states, there could be phase transitions.”

“In the past, I’ve had some exciting episodes,” he said, referring to his earlier work on anyons, particles with such unusual properties that some people doubted they could exist. Evidence for anyons was finally detected in 2005. “It’s a strange, curious idea, and it will be interesting to see where it goes.”

Explore further: Thermoelectric power plants could offer economically competitive renewable energy

More information: Alfred Shapere and Frank Wilczek. “Classical Time Crystals.” arXiv:1202.2537v1 [cond-mat.other]

Frank Wilczek. “Quantum Time Crystals.” arXiv:1202.2539v1 [quant-ph]

via: Science News

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User comments : 39

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Vendicar_Decarian
1.9 / 5 (14) Feb 20, 2012
Isn't any moving object - devoid of influence from other objects - a perpetual motion machine?

How about the electron in a hydrogen atom?

Planets orbiting a star?

Lurker2358
2.1 / 5 (15) Feb 20, 2012
Isn't any moving object - devoid of influence from other objects - a perpetual motion machine?

How about the electron in a hydrogen atom?

Planets orbiting a star?



Exactly what I thought of.

However, on closer inspection, those systems are imperfect and deteriorate over time due to various forces such as friction, frame dragging, etc.

but from my point of view, for all practical purposes, you are correct, those systems are and have always been perpetual motion machines.
TheGhostofOtto1923
1.9 / 5 (16) Feb 20, 2012
How about this?

"Persistent current is a perpetual electrical current, not requiring an external power source, that flows naturally through resistive metal."
http://en.wikiped..._current
but from my point of view, for all practical purposes, you are correct, those systems are and have always been perpetual motion machines.
Which is as usual egocentrically myopic in the extreme. Planetary orbits decay from tidal forces. Electron orbits do not decay. Unless you have a source which says they do?
Megadeth312
4.5 / 5 (11) Feb 20, 2012
Perpetual motion machines must do work, an object simply spinning in space is not considered perpetual motion.

Lurker2358
2.4 / 5 (13) Feb 20, 2012
How about this?

"Persistent current is a perpetual electrical current, not requiring an external power source, that flows naturally through resistive metal."
http://en.wikiped..._current
but from my point of view, for all practical purposes, you are correct, those systems are and have always been perpetual motion machines.
Which is as usual egocentrically myopic in the extreme. Planetary orbits decay from tidal forces. Electron orbits do not decay. Unless you have a source which says they do?


Allegedly, over obscenely long time periods they certainly decay, according to the mainstream model, because that ties into part of the "big freeze" theory of cosmology. All matter and energy eventually decay.

this is what all the big names in modern physics say anyway.

youtube.com/watch?v=zf2csQnE0jA

I tire of these games, Ghost.

I wonder whether you even bother to check this stuff for yourself, or if you've come to hypocritically rely on my integrity.
Callippo
2 / 5 (7) Feb 20, 2012
Isn't every wave a sorta time crystal?
Vendicar_Decarian
1.9 / 5 (10) Feb 20, 2012
"However, on closer inspection, those systems are imperfect and deteriorate over time due to various forces such as friction, frame dragging, etc" - Lurker

The requirement of these "time crystals" is that they be isolated from their surroundings, such that their quantum state is not altered.

Applying the same limitations on atoms or planets produces the same perpetual motion results.
Vendicar_Decarian
1.4 / 5 (9) Feb 20, 2012
The key concept behind the revelation in this article is that in the ground state a system can oscillate.

Given that individual particles are themselves characterized by temporal oscillations, I see nothing special here.
antialias_physorg
5 / 5 (11) Feb 20, 2012
Allegedly, over obscenely long time periods they certainly decay,

They decay - but there's no friction, frame dragging or whatnot involved (and the orbitals don't shrink, either). Proton decay - if it exists - is a probabilistic process (i.e. it happens suddenly, but with a very low probability)

And no - this has nothing to do with the 'big freeze'. The big freeze can very well happen with atoms still in it. Atoms can be at 0 Kelvin and still remain atoms.
axemaster
5 / 5 (3) Feb 20, 2012
So when they say that it exhibits periodic motion, do they mean that in a classical sense, or in a quantum sense? I.e. is the expectation value of position changing periodically? The article really doesn't make that clear.
sherifffruitfly
1.6 / 5 (8) Feb 20, 2012
"they wouldnt violate the second law of thermodynamics"

Please fire whoever writes your BS headlines. Immediately.

Sensationalistic headline deceit is for politics, not physics.
TheGhostofOtto1923
1.3 / 5 (13) Feb 20, 2012
I tire of these games, Ghost.
And I tire of youre not knowing how to post a full link?
I wonder whether you even bother to check this stuff for yourself, or if you've come to hypocritically rely on my integrity.
I watched your vid. Nothing in there about decaying electron orbits nor why that might ever happen. Maybe you want to post something from the cosmos series? Or at something which says 'Electron orbits will eventually decay because...'
They decay - but there's no friction, frame dragging or whatnot involved (and the orbitals don't shrink, either).
-And sorry - even opinions from anonymous germans do not qualify as valid references.
Short bloke
1 / 5 (1) Feb 20, 2012
The fundamental wave-particle duality of an electron.
Lurker2358
2.1 / 5 (7) Feb 20, 2012
Ghost:

Watch it again, you missed it.

Clearly, if the theory claims the entire universe will be made of nothing but photons, then all physical matter, including electrons, must decay.
antialias_physorg
4.6 / 5 (11) Feb 20, 2012
-And sorry - even opinions from anonymous germans do not qualify as valid references.

I didn't mean that the orbitals get smaller or somesuch (they are quantized). I meant that protons possibly decay. If they do then the atoms they were a part of will eventually decay (i.e. fall apart). This is a sudden event...not some slow 'spiralling in' of electrons (which is a wrong picture, anyways, because electrons do not orbit nuclei the way moons orbit planets)
javjav
5 / 5 (1) Feb 20, 2012
A system in its lowest energy state can not exist forever, it is a human concept that do not exist in reality. Not only because of particle decay, also because electrons and other particles are not 100% localized, and virtual particles can also appear and interact with it.
Birthmark
not rated yet Feb 20, 2012
Interesting.
Could we eventually harness the power of their kinetic energy?
antialias_physorg
5 / 5 (12) Feb 20, 2012
From the article:
He added that, even though time crystals might move continuously, they couldnt be used to generate useful energy since they cant be disturbed, and they wouldnt violate the second law of thermodynamics.

So the answer would be: No.
Deesky
3.3 / 5 (7) Feb 20, 2012
this has nothing to do with the 'big freeze'. The big freeze can very well happen with atoms still in it. Atoms can be at 0 Kelvin and still remain atoms.

Maybe so, but we'll never know as absolute zero temperature is unachievable.
Isaacsname
5 / 5 (2) Feb 20, 2012
How about this?

"Persistent current is a perpetual electrical current, not requiring an external power source, that flows naturally through resistive metal."
http://en.wikiped..._current
but from my point of view, for all practical purposes, you are correct, those systems are and have always been perpetual motion machines.
Which is as usual egocentrically myopic in the extreme. Planetary orbits decay from tidal forces. Electron orbits do not decay. Unless you have a source which says they do?


I'm sorry, what ?

http://en.wikiped...-PAR.svg

You are looking for a slow spiral or something Newtonian ?
animah
1 / 5 (2) Feb 20, 2012
Great work.

Quick question: The 2nd law depends on closed systems. Do closed systems really translate from math to modern physics where a particle is always unavoidably exposed to vacuum energy and quantum foam?
Urgelt
1 / 5 (2) Feb 21, 2012
The subject matter has nothing to do with "perpetual motion machines." Even as analogy, it fails utterly to connect to the subject.

Forgivable, perhaps. We don't know how much sleep the writer was missing. But don't do it again.
Thecis
5 / 5 (2) Feb 21, 2012
Planets around a sun DO have friction. Although the "vaccuum" in space is rather empty, it isn't exactly a vaccuum. Also, earth is slowed down by meteorites. Although all these contributions (friction and added mass) you do see a loss in velocity (over the billions and billions of years).

Regarding the electron around a atom core. Bohr suggested a planetary system to describe this. Due to the speed electrons would immediatly throw themselves into the atom core because of the centrigual force (I might state it politically incorect, therefore my apologies).
Clearly, this doesn't happen. Why? Because newtonian physics do not apply anymore and we need to use quantum physics. The electron is equally distributed at a certain distant (1s orbital) and if it a probability distribution, meaning it is likely to find the electron somewhere over there, but it can't be exactly pinpointed.
That is why the atom-system is not a perpetuum mobile system =perpetual motion machine in newtion physics
Vendicar_Decarian
2.6 / 5 (5) Feb 21, 2012
"Even as analogy, it fails utterly to connect to the subject." - Urgelt

It was a minor point of contention. But even the intended meaning of the article is not news.

cps
not rated yet Feb 21, 2012
Wouldn't a photon count as a time crystal?
antonima
2.3 / 5 (3) Feb 21, 2012
How about this?

"Persistent current is a perpetual electrical current, not requiring an external power source, that flows naturally through resistive metal."
http://en.wikiped..._current
but from my point of view, for all practical purposes, you are correct, those systems are and have always been perpetual motion machines.
Which is as usual egocentrically myopic in the extreme. Planetary orbits decay from tidal forces. Electron orbits do not decay. Unless you have a source which says they do?


How about this-

http://en.wikiped...ysics%29
"dark current is the relatively small electric current that flows through photosensitive devices such as a photomultiplier tube, photodiode, or charge-coupled device even when no photons are entering the device ... dark current flows due to the random generation of electrons and holes within the depletion region of the device that are then swept by the high electric field"
antonima
not rated yet Feb 21, 2012
If the particle they have theorized is truly stable, as being in the lowest energy state would imply, then it may be a first of its kind. It wouldn't be the first case of one of the fundamental symmetries having an exception.
WhiteJim
2.6 / 5 (7) Feb 21, 2012
"perpetual motion machine" is different than something having "perpetual motion". Everything has perpetual motion as it is now... in fact everything is not only in perpetual moton its perpetually accelerating to boot...
TheGhostofOtto1923
1.4 / 5 (9) Feb 21, 2012
Ghost:

Watch it again, you missed it.

Clearly, if the theory claims the entire universe will be made of nothing but photons, then all physical matter, including electrons, must decay.
No, clearly there are other ways for matter to turn into photons. Matter collapses into black holes and those eventually evaporate, as your movie states.

Please provide evidence for the decay of electron orbits or STFU.
axemaster
5 / 5 (2) Feb 21, 2012
A system in its lowest energy state can not exist forever, it is a human concept that do not exist in reality.

Actually it can. It's a mathematical concept, and thus not dependent in any way on human thinking.
antialias_physorg
3 / 5 (2) Feb 22, 2012
Wouldn't a photon count as a time crystal?

Tricky, because from the point of view of a photon no time passes. To it the event of emission and of being captured are simultaneous (this even goes if the photon isn't captured, ever, again (!))


How about this-

http://en.wikiped...ysics%29
"dark current is the relatively small electric current that flows

What about it? You have an external voltage (power source) along which the charged particles (electrons, holes) flow.
The dark current gets less the cooler you make your photomultiplier. This is why many infrared/photomultiplier detector systems are cooled (e.g. military targetting systems or infrared telescopes)

Dark current is a probabilistic occurence. A system that has a temperature above absolute zero contains some (thermal) energy. But that energy isn't (at all times) spread perfectly evenly throughout the system. If enough of it (by chance) happens to be at one point an electron can be liberated from its atom.
Isaacsname
5 / 5 (1) Feb 23, 2012
Great work.

Quick question: The 2nd law depends on closed systems. Do closed systems really translate from math to modern physics where a particle is always unavoidably exposed to vacuum energy and quantum foam?


http://en.wikiped..._theorem
Anda
5 / 5 (1) Feb 23, 2012
Nothing here about perpetual motion machines. You're all discussing because of a title that is wrong.
juanko
1 / 5 (2) Feb 24, 2012
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camel
1 / 5 (2) Feb 24, 2012
a friend's sister-in-law makes $65 hourly on the laptop. She has been laid off for 6 months but last month her pay was $19426 just working on the laptop for a few hours. Go to this web site and read more NuttyRich dot com
mauro48it
not rated yet Feb 25, 2012
posso immaginare un materiale con una perfetta elasticità, similmente ad un materiale con perfetta conducibilità elettrica.
Questo materiale, sebbene perfettamente isolato dall'ambiente circostante, potrebbe essere sede di vibrazioni meccaniche perpetue.
Sarebbe questo un time cristal?
Forse cercavi: posso immaginare un materiale con una perfetta elasticità, similmente ad un materiale con perfetta conducibilità elettrica.
Digita il testo o l'indirizzo di un sito web oppure traduci un documento.
Annulla
ingleseitalianospagnoloAlpha
I can imagine a material with a perfect elasticity, similar to a material with perfect electrical conductivity.
This material, though perfectly isolated from the environment, could be the site of perpetual mechanical vibrations.
This would be a time crystal?
ECOnservative
1 / 5 (1) Feb 25, 2012
How is this different from Planck scale "jitter" as currently being proposed to be tested with the Holometer? At the Planck scale, time, energy and matter are supposedly the same thing, at least in theory.
Lurker2358
1 / 5 (4) Feb 26, 2012
No, clearly there are other ways for matter to turn into photons. Matter collapses into black holes and those eventually evaporate, as your movie states.

Please provide evidence for the decay of electron orbits or STFU.


http://arxiv.org/.../0312325

and

http://en.wikiped...operties
antonima
not rated yet Feb 26, 2012

What about it? You have an external voltage (power source) along which the charged particles (electrons, holes) flow.
The dark current gets less the cooler you make your photomultiplier. This is why many infrared/photomultiplier detector systems are cooled (e.g. military targetting systems or infrared telescopes)


In basic physics, a voltage does not necessarily require a power source, however that may not be the case with how a photodiode works.

Dark current is a probabilistic occurence. A system that has a temperature above absolute zero contains some (thermal) energy. But that energy isn't (at all times) spread perfectly evenly throughout the system. If enough of it (by chance) happens to be at one point an electron can be liberated from its atom.


Right, the point is that this thermal energy can theoretically do some tiny amount of work through this dark current, even though it actually impedes usefulness in real thermal imaging devices.

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