
Scientists unveil new form of matter: Time crystals - mpweiher
https://www.eurekalert.org/pub_releases/2017-01/uoc--sun012617.php
======
krylon
It is funny how advanced physics sounds to my layperson ears like something a
stoned teenager might come up with.

This reminds me somehow of the "one-electron universe":
[https://en.wikipedia.org/wiki/One-
electron_universe](https://en.wikipedia.org/wiki/One-electron_universe)

(Just to be clear: I am not mocking physicists, it just seems the universe is
really, really weird.)

~~~
keldaris
Or, as I would put it, the universe at large is simply vastly richer than our
limited intuitions, a natural consequence of the limited range of physical
properties that supports human life. It would be really strange if the
universe didn't seem weirder and weirder the further we stray from our
immediate perceptions.

------
witty_username
> The idea was proposed by Frank Wilczek in 2012. His speculation was that a
> construct would have a group of particles that move and periodically return
> to their original state, perhaps moving in a circle, and form a time
> crystal. In order for this perpetual motion to work, the system must not
> radiate its rotational energy.

I thought perpetual motion violates the laws of thermodynamics. Does quantum
physics cause the laws of thermodynamics to break down?

~~~
stephengillie
Niels Bohr proposed that electrons don't have enough energy to radiate away,
and thus are forced to continue to spin around the nucleus.[0] This was the
seed that fruited the quantization of energy and eventually our modern
understanding of Quantum Mechanics.

In a way, the quantization of reality at very small scales does appear to
prevent the laws of thermodynamics from occurring. This is just one form of
Zero-Point Energy[1]. Maybe these time crystals are another form - maybe some
large objects radiate some kind of time-entropy, and these are too small (or
configured in some other way), such that they are also mechanically prevented
from doing so?

IANA theoretical physicist - I merely play one on the internet. Expert opinion
and advice is welcome.

[0][https://physics.stackexchange.com/questions/18473/where-
do-e...](https://physics.stackexchange.com/questions/18473/where-do-electrons-
get-their-ever-lasting-circulating-energy)

[1][https://en.wikipedia.org/wiki/Zero-
point_energy](https://en.wikipedia.org/wiki/Zero-point_energy)

~~~
keldaris
Disclaimer: Theoretical physics postdoc, working in an unrelated subject area.
Not necessarily an expert, but I do have some comments.

> Niels Bohr proposed that electrons don't have enough energy to radiate away,
> and thus are forced to continue to spin around the nucleus.[0] This was the
> seed that fruited the quantization of energy and eventually our modern
> understanding of Quantum Mechanics.

The first sentence is correct, though the history directly begins in 1900 with
Planck's quantization hypothesis in the context of black body radiation.
Bohr's paper, which I assume you're referring to, came in 1913.

> In a way, the quantization of reality at very small scales does appear to
> prevent the laws of thermodynamics from occurring. This is just one form of
> Zero-Point Energy[1]. Maybe these time crystals are another form - maybe
> some large objects radiate some kind of time-entropy, and these are too
> small (or configured in some other way), such that they are also
> mechanically prevented from doing so?

I do to take an issue with this paragraph, in that it doesn't really map to
any well defined concepts in modern physics. The "quantization of reality at
very small scales" (by which I assume you're referring to the speculative idea
of fundamentally quantized spacetime) doesn't really have anything directly to
do with thermodynamics - the laws of thermodynamics are necessarily
statistical laws, produced by the behavior of ensembles defined by particular
distributions. They have no particular validity in (most) very small scale
systems and I don't see how the quantization is relevant here. Nor do any of
these remarks help you violate the conservation of energy with respect to any
larger systems.

I have no idea what "time-entropy" means, but generally speaking this notion
of time crystals doesn't have anything intrinsically to do with violating
energy conservation or producing useful work (in the physical sense) in any
new fashion. Rather, it represents a fairly ingenious way of applying the
established mathematical tools of analyzing symmetries to systems that exhibit
complex periodic behavior rather than just spatial symmetries. In that regard,
I think the example of satellite motion presented by Latham Boyle [1] was very
illustrative without being misleading or overly suggestive.

I hope this response isn't overly snarky, I just wanted to clarify a few
misconceptions I've seen a lot in the last few days.

[1] [https://arxiv.org/abs/1407.5876](https://arxiv.org/abs/1407.5876)

------
jdoliner
It seems remarkable that time crystals were theorized in 2012 and confirmed in
2017. It took several decades for experimental methods to catch up to the
Higgs Boson for example.

~~~
ajkjk
Well, the Higgs has strict technical requirements -- a collider capable of
getting comfortably over the energies needed to create the thing without it
fading into background noise. That took a lot of engineering progress,
software, money, and political will to get to. Whereas this is a much less..
involved creation. The experimental requirements aren't nearly as vast.

(I found some details on the requirements here:
[https://physics.stackexchange.com/questions/246841/why-
did-i...](https://physics.stackexchange.com/questions/246841/why-did-it-take-
so-long-to-find-the-higgs) )

------
contravariant
What's the reasoning behind calling it non-equilibrium matter? Sure if you
need to keep sending in laser pulses you can't exactly call it an equilibrium,
but the original definition had periodic behaviour in the ground-state, which
you'd think would be considered an an equilibrium.

~~~
bodhiandphysics
It's not a thermodynamic equilibrium. The system does not have maximum
entropy, and so, eventually the spin crystal will decay. The problem is
eventually might be larger than the age of the universe by a factor of some
really really large number

------
DINKDINK
>"Wouldn't it be super weird if you jiggled the Jell-O and found that somehow
it responded at a different period?" Yao said. "But that is the essence of the
time crystal. You have some periodic driver that has a period 'T', but the
system somehow synchronizes so that you observe the system oscillating with a
period that is larger than 'T'."

I don't have anywhere close the knowledge and background that these physicists
have but no that wouldn't be very odd if you observed oscillations that were
something other than T. In music, this is called a harmonic. If you push and
pull on a garage door with a period of T or a frequency of 1/T the door will
product oscillations at frequencies other than 1/T

~~~
Groxx
Harmonics only increase the frequency though, right? Not decrease? You can't
get an octave _lower_ note from plucking a guitar string in a certain way.

~~~
ithkuil
Harmonics (overtones) are already there. By definition the fundamental tone is
just the lowest frequency. You can isolate harmonics either by amplifying the
desired frequency or by muting a longer wave length e.g. by placing a finger
on a string in a place that is a node of the higher frequency harmonics but
not a node in the lower frequency. Thus by definition you cannot create
subharmonics, well unless you cheat :-)
[http://www.marikimura.com/subharmonics.html](http://www.marikimura.com/subharmonics.html)

------
spraak
This sounds like science fiction, which really tickles me in a positive way
(as in, I am not criticizing it but rather it's highly exciting yet very
fantastical compared to where physics was at when I studied it). I'd almost
see this in an episode of Steven Universe[0], after the creators got stoned
with a physicist one afternoon

[0]
[https://en.wikipedia.org/wiki/Steven_Universe](https://en.wikipedia.org/wiki/Steven_Universe)

------
aisofteng
Great to see links to the papers!

~~~
JBiserkov
Eurekalert is basically links to papers with some text submitted by the author
and/or publisher PR person.

------
pizza
So.. what new kinds of electronics do we get..?

~~~
ra
Flux capacitors?

~~~
rms
We got those with the
[https://en.wikipedia.org/wiki/Memristor](https://en.wikipedia.org/wiki/Memristor)

------
drivingmenuts
I know the answer is probably going to be "What the hell can't they be used
for?!!?" but what the hell can they be used for? Is that maybe a question for
later?

All that's coming to mind is permanent storage with the emphasis on permanent.

~~~
fbrusch
One thing that comes to mind is reversible computing.
([https://en.wikipedia.org/wiki/Reversible_computing](https://en.wikipedia.org/wiki/Reversible_computing)).
When computation is irreversible (as is the case for all our current
information elaboration systems and substrates), it is bounded below in the
energy that dissipates. The bound is quantified by the Landauer principle, and
has to do with the entropy involved in "forgetting" the previous states. If a
computation process is reversible, it doesn't incur in such limit. One can
maybe imagine time crystals concocted to carry out useful computation,
spending no energy in the process.

~~~
DonHopkins
Tommaso Toffoli [1] invented the reversible Toffoli Gate [2].

Norman Margolus [3] invented the Margolus Neighborhood [4], which is useful
for rotationally symmetrical cellular automata rules [5] like billiard ball
cellular automata [6] [7].

Toffoli and Margolus also explored other energy conserving cellular automata
like spin glasses [8], which are disordered magnets that store energy in the
bonds between atoms.

Edward Fredkin [9] invented reversible second order cellular automata [10],
which look back two steps in time, and are useful for simulating the Ising
model of ferromagnetism.

Then again, maybe Otis Eugene "Gene" Ray, the "wisest man on earth", caused
this article to quantum tunnel through time from April 1 1997 [11] [12].

To play with the following code that implements a spin glass, go here:
[http://donhopkins.com/home/CAM6/](http://donhopkins.com/home/CAM6/) then
click the square in the upper left, click "Rules", pick the rule "von Neumann
Spins Only", and draw in the cells by dragging around with the left button.
JavaScript sure cooks these days!

    
    
        // ruleFunction_VonNeumann_spinsOnly computes the Spins Only rule
        // for VonNeumann neighborhood lookup table.
        //
        // Cellular Automata Machines, p. 190, section 17.3, Spins Only.
        //
        // This models a spin glass, which is a matrix of atoms with
        // magnetic spins (up or down).
        //
        // https://en.wikipedia.org/wiki/Spin_glass
        //
        // A spin glass is a disordered magnet with frustrated
        // interactions, augmented by stochastic positions of the spins,
        // where conflicting interactions, namely both ferromagnetic and
        // also antiferromagnetic bonds, are randomly distributed with
        // comparable frequency. The term "glass" comes from an analogy
        // between the magnetic disorder in a spin glass and the
        // positional disorder of a conventional, chemical glass, e.g.,
        // a window glass.
        //
        // Spin glasses display many metastable structures, leading to a
        // plenitude of time scales which are difficult to explore
        // experimentally or in simulations.
        //
        function ruleFunction_VonNeumann_spinsOnly(ruleDict, state) {
    
            // This makes a checkerboard pattern that alternates every
            // step, so we can apply the rule to every other cell every
            // other step. That way we know our four neighbors will not be
            // changing at the same time we are changing.
            var activeSite =
                (state.horiz ^ state.phaseTime) == state.vert;
    
            // Count how many of our four neighbors are set.
            var sum4 =
                     state.n0 +
                state.w0 + state.e0 +
                     state.s0;
    
            // When it is our turn to run in this cell (at every other
            // step), then we flip our value if exactly two of our
            // neighbors are up, and two are down. Since energy is stored
            // in two adjacent cells with different spins, we can flip our
            // value without changing the energy of the system, because
            // the perimeter between up and down cells remains the same.
            var result =
                (activeSite
                    ? [
                        state.c0,
                        state.c0,
                        state.c0 ^ 1,
                        state.c0,
                        state.c0
                      ][sum4]
                   : state.c0);
    
            return result;
        }
    

[1]
[https://en.wikipedia.org/wiki/Tommaso_Toffoli](https://en.wikipedia.org/wiki/Tommaso_Toffoli)

[2]
[https://en.wikipedia.org/wiki/Toffoli_gate](https://en.wikipedia.org/wiki/Toffoli_gate)

[3]
[https://en.wikipedia.org/wiki/Norman_Margolus](https://en.wikipedia.org/wiki/Norman_Margolus)

[4]
[https://github.com/SimHacker/CAM6/blob/master/javascript/CAM...](https://github.com/SimHacker/CAM6/blob/master/javascript/CAM6.js#L4282)

[5]
[https://github.com/SimHacker/CAM6/blob/master/javascript/CAM...](https://github.com/SimHacker/CAM6/blob/master/javascript/CAM6.js#L5636)

[6]
[https://en.wikipedia.org/wiki/Reversible_cellular_automaton#...](https://en.wikipedia.org/wiki/Reversible_cellular_automaton#Billiard_ball_computation_and_low-
power_computing)

[7] [https://en.wikipedia.org/wiki/Billiard-
ball_computer](https://en.wikipedia.org/wiki/Billiard-ball_computer)

[8]
[https://en.wikipedia.org/wiki/Spin_glass](https://en.wikipedia.org/wiki/Spin_glass)

[9]
[https://en.wikipedia.org/wiki/Edward_Fredkin](https://en.wikipedia.org/wiki/Edward_Fredkin)

[10] [https://en.wikipedia.org/wiki/Second-
order_cellular_automato...](https://en.wikipedia.org/wiki/Second-
order_cellular_automaton)

[11]
[https://en.wikipedia.org/wiki/Time_Cube](https://en.wikipedia.org/wiki/Time_Cube)

[12]
[https://web.archive.org/web/19980629180418/http://www.timecu...](https://web.archive.org/web/19980629180418/http://www.timecube.com/)

~~~
throwawayish
Twelve citations in a HN comment has to be some kind of record.

~~~
DonHopkins
I was only getting started! There are so many much more interesting cellular
automata than Life, which is so overrated. As Marvin the Paranoid Android
says, "Life? Don't talk to me about life! Loathe it or ignore it. You can't
like it."

The classic book on the subject is "Cellular Automata Machines: A New
Environment for Modeling" [1]

This article has a lot of great references: "When–and how–can a cellular
automaton be rewritten as a lattice gas?" [2].

And Fredkin's "Digital Mechanics: An Informational Process Based on Reversible
Universal Cellular Automata" [3] is also a classic paper about the subject.

Fredkin, Toffoli, Margolus and others have done a lot of interesting research
into reversible computation, which has many practical and theological [4]
applications, and will some day be very useful at the Restaurant at the End of
the Universe [5].

[1] [https://mitpress.mit.edu/books/cellular-automata-
machines](https://mitpress.mit.edu/books/cellular-automata-machines)

[2]
[http://www.sciencedirect.com/science/article/pii/S0304397508...](http://www.sciencedirect.com/science/article/pii/S0304397508003629?np=y&npKey=9d7c391743e27ff27ce1020a5bb9f3cdf2223427de10ab1b2e6e1d0523704429)

[3]
[https://books.google.com/books?id=6o6zx5MRRcQC&pg=PA254&lpg=...](https://books.google.com/books?id=6o6zx5MRRcQC&pg=PA254&lpg=PA254&dq=fredkin+%22Digital+Mechanics:+An+Informational+Process+Based+on+Reversible+Universal+Cellular+Automata%22&source=bl&ots=n13CPseK8q&sig=k7VesMLt0hjQtl_7u5Oedh3E0-o&hl=en&sa=X&ved=0ahUKEwi-
teb_lOXRAhUD0WMKHX1BAIQQ6AEINTAD#v=onepage&q=fredkin%20%22Digital%20Mechanics%3A%20An%20Informational%20Process%20Based%20on%20Reversible%20Universal%20Cellular%20Automata%22&f=false)

[4]
[http://www.tandfonline.com/doi/pdf/10.1080/15665399.2010.108...](http://www.tandfonline.com/doi/pdf/10.1080/15665399.2010.10820012)

[5]
[https://en.wikipedia.org/wiki/Omega_Point](https://en.wikipedia.org/wiki/Omega_Point)

------
eip
Are these crystals cubic? Like some sort of time cube?

------
sliken
Since when is an arxiv.org paper and a physics letter mean that significant
new piece of physics is confirmed?

~~~
jeffwass
FYI, 'Physical Review Letters' is probably the most prestigious physics-
focused journal one can publish in. Here's a link the the actual PRL paper.
[http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.118...](http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.118.030401)

Back when I was in physics grad school, getting a paper in Nature or Science
was the dream. But a paper in PRL was also considered a big deal.

------
kahrkunne
"time crystals"

Am I the only one who thinks science is starting to sound more and more like
magic?

~~~
eternalban
The name is whimsical. A "crystal" is a repeated pattern in space. So a "time
crystal" is a pattern repeated in time.

~~~
throwawayish
Oh. That makes a lot more sense. Thanks

------
lngnmn
Oh, god. What is time exactly, I forgot?

~~~
bcjordan
Crystals?

~~~
lngnmn
Sure.

But according to some crummy philosophy, time as phenomena does not exist,
because it requires an observer.

The simplest example would be how life (at the level of molecular biology,
proteins) uses only pattern-matching but no counting, binding-sites and
concentration-based regulations, but no counters. Never. Because a counting
requires an observer. But molecular biology precedes any consciousness, so, no
counting or numbers. Only pattern matching of physical shapes, compound
structures. (Precedes here means that in a whole process of evolution of life
it some patterns emerged _prior_ to others).

Same holds for time. The notion of time, like counting, requires a
consciousness. Like any other abstraction.

But, of course, who studies philosophy in the age of hipsters? So lets ask a
much simpler question: what exactly replicable experiment proves the existence
of time as an independent phenomena (independent of any physical process, the
phenomena-in-itself), so any goddamn crystals could exist?

~~~
pazimzadeh
Are you sure? If I remember correctly, glycosylation/mannosylation of folding
proteins acts as a timer giving the protein some amount of chances to fold
properly before being discarded.

[https://www.ncbi.nlm.nih.gov/pubmed/15950873](https://www.ncbi.nlm.nih.gov/pubmed/15950873)

~~~
lngnmn
Nonexistence of time is a fundamental principle, which helps to prune out lots
of nonsensical dogmatic hipster's pseudo-science.

It is like an ancient hack - to see things as they are one have to _remove an
observer_. One could hack physics this way.

It has lots of philosophical implications, when one leans to recognize the
fundamental difference between what is and chimeras (or memes) created by
mind. Time is one such meme. Numbers is another.

------
davesque
Finally, the last piece for my TARDIS.

~~~
anotheryou
no humor please, this is HN

edit: I wonder: did I get downvoted because someone does not share my humor,
as a joke, or because someone didn't get the irony?

~~~
throwaway413
Not sure it was recognizable as a joke. But once it was, it was damn funny!

------
demonshalo
ELI5?

~~~
labrador
From what I gather, and someone can tell me if I'm wrong, time crystals
vibrate in a repeatable pattern that can be accelerated by hitting it with a
laser. Scientists haven't imagined a use for this yet.

------
basicplus2
I don't understand.. I read it but it is meaningless jibberish to me

~~~
Etheryte
Perhaps Wikipedia can lend a hand, the description there is quite easy to
follow: [https://en.wikipedia.org/wiki/Space-
time_crystal](https://en.wikipedia.org/wiki/Space-time_crystal)

~~~
vinchuco
Is it really meaningful though? I could call a human a space-time worm, and it
makes no difference.

~~~
Iv
It is. Most matter we think about is what you would call a space-time worm. A
pattern of 4d continuous worms interweaved together.

If at a given time the pattern stops, we consider that the structure broke.
Matters that spontaneously break are unstable.

Materials we call impossible are only impossible under these conditions :
stable a d continuous in time. The idea of matter that may be discontinuous in
time but still display some characteristics of stable solid matter is pretty
new.

------
debt
Am I wrong but couldn't this be used to create an extremely powerful quantum
supercomputer?

~~~
SomeStupidPoint
How do you think this would help with a quantum computer?

Not that Wilczek's work is unrelated to quantum computers, just not sure that
this bit is.

Ed: For anyone wondering about the connection, Wilczek worked on anyons, which
are the basis of Microsoft's research into quantum computing.

