We have, perhaps, all experienced those 'heat' packs wherein a local disturbance causes a crystal structure to rapidly dissipate through the medium, releasing heat in the process. Nothing really 'moves' from one point in the pack to another, except the physical transformation into a crystalline like structure.

Now consider this happening as a result of quantum effects, perhaps quantum tunneling, quantum entanglement, or other unknown quantum effect. Consider also that this might be happening in some unknown medium or matter such as dark matter. This question is not about the 'how' or the 'method'.

Is there any practical or theoretical constraint that absolutely prevents any form of crystal from propagating in a structure whose boundary 'grows' faster than a speed 'c'?

For instance (for illustrative purposes but not limited to), maybe one atom (or whatever dark matter particles would be called once we find them) becomes a seed that causes a bond to form with a neighboring dark matter particle through quantum tunneling, which forms a bond with another neighboring dark matter particle (anthropomorphizing, "Oh, my, a particle just appeared in me, so I must do this" type of thing), and so on, forming some form of crystal lattice, that is propagating away from the original seed at a speed that exceeds 'c'? Since nothing is actually traveling faster than 'c' (the quantum tunneling particle does not move from A to B, it just appears at B, never really having been at A in the first place) except the arrangement of particles (perhaps an almost instantaneous chain reaction of quantum effects), and no information is actually traveling faster than 'c' (because nothing was known or defined about the particle until it appeared at point B), is there any specific law or principle or equation or theory or model in the existing physics textbook that prevents this from happening?

This is NOT about any limitation proscribed by any existing known theories of crystal formation and atomic bond formation in known substances, but about a limitation based on universal principles that would apply to ANY form of bond formation in ANY substance, known or unknown.

Please note, this is not asking 'could it happen' or 'how would it happen' or 'what are the conditions under which it would happen'. It is asking if there is anything we positively universally theoretically accept as fact that would prevent it from happening, notwithstanding we don't know how it would happen?



This question seems to have generated some controversy, based on misapprehension of the question. It is founded on a very complex concept, not always readily apparent. Here is a thought experiment that illustrates and perhaps clarifies the basis of it.

"Wormhole' technology and entanglement have generally been accepted as potentially possible. Imagine an infinite number of wormholes (folds in space/time) joining the seed node to an infinite number of 'particles', perhaps of dark matter, of which we hypothesize exists but we know very little about. The 'crystalization trigger' that changes the particles into a crystal 'structure' travels through these worm holes to every 'target' at 'relatively' the same 'time'. It would appear to an universal observer that the crystal had formed almost instantaneously, everywhere, and would certainly have 'grown' faster than the speed 'c' - limited by the speed of travel through a wormhole. (However, the information about such a formation would not reach the observer any faster than 'c'). But, like Einstein said, things can appear to one observer as being very different to how the same thing appears to another observer.

My research and knowledge has not revealed any principle or limitation that is posited by the current physics textbook that precludes this thought experiment from happening in reality. The limitation on the speed of information and matter to less than 'c' is through the normal unfolded space/time, and that seems to be generally accepted. It is my understanding that it does not necessarily apply to folded space/time situations.

The question is, beyond the accepted 'laws' that neither information nor matter can travel through normal space/time faster than the speed 'c', are there any other specific limitations to 'c' that would also apply to, say, wormholes and entanglement?

Incidentally, there are some good and sound speculations that posit 'entanglement' is actually an occurrence of a 'wormhole' or fold in space/time such that even though these two particles appear to us in normal space/time to be a great distance apart, they are really side-by-each in the quantum 'folded universe' world. An infinite number of 'wormholes' is thus not beyond current conjecture, just like dark matter, even though our anthropic viewpoint cannot 'detect' them.

An insight into this concept is given by

A Cryptic Equation The new wormhole work began in 2013, when Jafferis attended an intriguing talk at the Strings conference in South Korea. The speaker, Juan Maldacena, a professor of physics at the Institute for Advanced Study in Princeton, New Jersey, had recently concluded, based on various hints and arguments, that “ER = EPR.” That is, wormholes between distant points in space-time, the simplest of which are called Einstein-Rosen or “ER” bridges, are equivalent (albeit in some ill-defined way) to entangled quantum particles, also known as Einstein-Podolsky-Rosen or “EPR” pairs. The ER = EPR conjecture, posed by Maldacena and Leonard Susskind of Stanford, was an attempt to solve the modern incarnation of the infamous black hole information paradox by tying space-time geometry, governed by general relativity, to the instantaneous quantum connections between far-apart particles that Einstein called “spooky action at a distance.” https://www.quantamagazine.org/newfound-wormhole-allows-information-to-escape-black-holes-20171023/

  • $\begingroup$ By "c" do you mean the speed of light? $\endgroup$ – David Feb 21 at 16:18
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    $\begingroup$ If the crystal is big like a galaxy cluster, it will grow up (expand to be correctly) faster than 'c' due to universe expansion. But of course a so big crystal cannot exist, and if you try to create it it will collapse due to gravity. $\endgroup$ – Stefano Balzarotti Feb 21 at 16:36
  • $\begingroup$ "consider this happening as a result of quantum effects, perhaps quantum tunneling, quantum entanglement, or other unknown quantum effect" - are you asking us to consider science that does not exist yet? $\endgroup$ – Alexander Feb 21 at 17:34
  • $\begingroup$ I mean 'C' the constant, the universal speed limit of the universe. It is just coincidentally the speed of light under certain conditions. $\endgroup$ – Justin Thyme the Second Feb 21 at 22:00
  • $\begingroup$ @Stefano Balzarotti You are assuming that it is made of matter that has mass. Apparently, many will argue that dark matter cannot exist, yet many will also argue that it does. $\endgroup$ – Justin Thyme the Second Feb 21 at 22:03

Information can't travel faster than c. That's what the implication of light speed boils down to.

Crystal formation faster than c would require that atoms at some great distance change position/structure before any "signal" could reach them to let them know to do so. While they might spontaneously crystallize on their own, it wouldn't necessarily be in an orientation with the crystallization that will soon catch up with them.

Basically you just can't trick light speed. Imagine you had a steel rod that was 4 light years long. You want to tell someone at Alpha Centauri that you'll be visiting in 4 years and you want them to bake you a cake. You have infinite strength, you push the rod, they see it move, and voila... FTL communications, right? They have 4 years to prepare.

But alas, no. This steel rod will take far longer than 4 years for him to see it "push" on the far end. The "push" only propagates along the steel rod at the speed of sound in steel (or something like that). The universe has it in for us.

Your question is flawed. In the absence of a phenomenon which is shown to be FTL or FTL-like, crystal formation cannot propagate faster than the speed of light. Quantum tunneling isn't magic wormhole technology and it does not occur faster than light. The spooky thing about it is that particles appear to go through barriers without penetrating or going around them... but they still require some sub-c time to do the tunneling.

If your creepy friend can walk through solid doors, he still takes 35 minutes to drive across town to perform the trick.

Whether there are implications where crystals form across barriers where the atoms don't actually come into contact I cannot say. That sounds fringey but not impossible.

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  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$ – Monty Wild Feb 25 at 20:28

It depends on what you mean by propagate. Phase velocity for an EM wave can be greater than c.


Nothing is actually traveling faster than light. This makes intuitive sense if you looks at a wave machine, like in this classic video.


The waves don't actually move along the ladder, the dots are just going up and down. The "velocity" of the wave moving along the machine is just an illusion.

We could also think of the funny observation of a laser point on the Moon "traveling" faster than c. Sit on the Earth with a laser pointer that is sufficiently powerful as to show up on the Moon as a point. Flick it around. If you were on the Moon and considered the point to be an actual object, it would appear to be moving around with great velocity, perhaps even faster than 'c.'Of course, you know that it isn't really an object. The photons are all coming from Earth and obeying the speed limit. But since they are all in flight simultaneously, the point where they intersect the surface of the Moon can "move" faster than 'c.'

I don't know much about crystal growth, but it strikes me that if you had some medium that would crystallize when hit by the laser, or when interacting with (say for example) the peak of an EM wave, it could appear to grow faster than 'c' under the influence of either of these phenomenon. Information about the lattice orientation would have to be propagated I guess, but perhaps that could be carried by the laser?

Note that all of these mechanism in essence require setting up a thing in advance that will come to fruition in multiple places such that the crystallization appears to be propagating faster than c. No information can travel faster than c, no matter what quantum effects you want to throw in there.

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    $\begingroup$ Your answer is extremely useful. The concept of this crystal growth, as proposed, is that entangled particles or particles that have 'tunneled' are the cause of the crystallization. Therefore, if two particles crystallized effectively at the same time, but were a distance apart, it would appear like the crystal growth exceeded the speed of 'c'. The essence of the question was that, indeed, no information was transferred. And, as I made clear, this is NOT 'normal' crystal growth. It is NOT mediated by limitations on 'normal matter' crystal formation. No knowledge of crystal growth needed. $\endgroup$ – Justin Thyme the Second Feb 21 at 23:02
  • $\begingroup$ '...require setting up a thing in advance...' But it doesn't have to be a specific thing for a specific crystal, it could be a generic thing for ANY crystal, for ANY 'seed point'? Like saturating a solution with salt, and causing a seed point to occur anywhere in the solution? $\endgroup$ – Justin Thyme the Second Feb 21 at 23:52
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    $\begingroup$ @JustinThymetheSecond, it's a little tricker than that. If an observer can control when crystallization occurs, then no, it can't all crystallize at once, because that would be transmitting information FTL. It has to either be random, or controlled by some process that was set in motion previously which obeys the light speed limit. $\endgroup$ – Matthew Feb 22 at 5:50
  • $\begingroup$ I'm also a big fan of VSauce's What is the speed of dark? which explores the same situations. $\endgroup$ – Cort Ammon Feb 22 at 8:40
  • $\begingroup$ @Matthew The observer is just controlling when the first seed crystal has changed. Everything else beyond that is no longer under observer control. It is all just a 'natural' process, the same way that the growth of the crystal in the heat pack is not under user control once the process is started. $\endgroup$ – Justin Thyme the Second Feb 22 at 14:33

The specific question that can be answered is, can the crystal propagate at faster than c. That is, if it started growing at some disturbed location and spread out from there, could it exceed c.

The answer to that is a flat no. Crystals operate on electromagnetism. Electrons and positively charged nuclei. If you get a crystal really exotic you might possibly bring in some weak nuclear.

These forces operate at a maximum of the speed of light. This is backed up by more than one century of experimentation. Winner and still Heavy Weight Champion of the World, Relativity.

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    $\begingroup$ It was a tedious homework assignment in my first year of grad school. But QM does not permit information to travel faster than light. So, no, can't be done. $\endgroup$ – puppetsock Feb 21 at 17:51
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    $\begingroup$ I have two entangled particles separated by 1LY. I observe some property of one of them. Due to entanglement, I know that the other is in the same state. As I understand it, this is how QE works... but it doesn't transmit information. If I understand this correctly (and it's plausible I don't), then I think spontaneous crystal formation would also be plausible. Again, the key is that formation does not transmit information. This means I also can't influence formation, because that would allow information to be transmitted. $\endgroup$ – Matthew Feb 21 at 18:03
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    $\begingroup$ @Matthew It's waaaay outside this SE. But, no, you don't know that at all. What you get is Bell's theorem. You look for, for example, plus or minus. If you sit measuring your end, you get exactly the same results no matter what is happening at the other end. There is no change whatever in your observations regardless of what the other observer does. You cannot tell if the other observer is even present. $\endgroup$ – puppetsock Feb 21 at 19:30
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    $\begingroup$ @Matthew You said "I know that the other is in the same state." No, you don't. You don't even know if there is another observer. You sit and take your readings, you get a random series of + and -. You get this if the other observer measures. Or if he does not. Or if he turns his device 90 degrees to yours. Or if he performs his measurement one light year farther away or closer. Or if he takes his device and smashes it. You don't know the other particle is in the same state. $\endgroup$ – puppetsock Feb 21 at 21:33
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    $\begingroup$ @JustinThymetheSecond Yes, the crystal growth does transfer information: a) the information that the crystal is growing, and that the atoms should get in line, and b) the information about the orientation of the growing crystal in space. So, unless you manage to put your system into a fully entangled state beforehand with the superposition of all possible crystal orientations, and the trigger is just measuring that orientation locally, you won't get around the information travel theorem. And even in that case, the setting up of the entangled state would be the actual growing of the crystal. $\endgroup$ – cmaster - reinstate monica Feb 22 at 23:11

Crystal growth cannot propogate faster than light in anyway that would transfer information. In other words, imagine there are two points in the crystal medium, A and B, distance d apart. Point B cannot crystallize because of any event at point A that didn't occur at least d / c units of time in the past, otherwise information has been tranfered faster than light. Specifically, an observer at B could know someone initiated crystalization at A sooner than they would know from a light speed signal.

However, there's nothing prohibiting the entire crystal medium from crystalizing simultaneously if the above restriction is respected. For instance, in a pool of crystal medium of diameter x, it's possible that "intiating crystallization" at any point in the pool has no observable effect until x / c units of time later, at which point the entire pool crystallizes at once. No information would be transfered faster than light, because an observer at one end of the pool would know it was going to crystalize before it actually did if a light speed signal was sent from the other end when the crystalization was initiated. I have no idea what mechanism might cause this, but since no information would be transfered, it's theoretically possible.

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  • $\begingroup$ So you are saying that in an entangled pair A and B, B can not be defined by A until a time period d/c elapses, yet they occur instantaneously. Methinks your physics textbook that you are consulting is not yet thick enough, and is missing chapters on quantum physics. 'Entanglement' is not limited to 'c' because no information is transmitted, not because there is a law that says a related change in two things a distance apart can not occur at the same time. $\endgroup$ – Justin Thyme the Second Feb 22 at 15:10
  • $\begingroup$ 'Specifically, an observer at B could know someone initiated crystalization at A sooner...' Likewise when traveling using worm holes, an observer at B could somehow know someone initiated travel at A sooner than they would know from a light speed signal. Yet wormhole travel is generally accepted as feasible and non-contradictory to the existing physics text book. If I posited an infinite number of worm holes, connecting all of the particles in the crystal, and the 'signal' traveled through these worm holes to every crystalized 'particle', as a thought experiment, what would be your retort? $\endgroup$ – Justin Thyme the Second Feb 22 at 15:16
  • $\begingroup$ @JustinThymetheSecond Entaglement does not transfer any information. An observer of particle B would have no indication whether or not particle A has been manipulated. If you still think entanglement transmits information, try to devise a scheme to send a sequence of bits FTL using entanglement; it's not possible. Wormholes, on the other hand, warp space. If a light speed signal took the same shortest path, through the wormholes, it would arrive no later than the front of crystallization. This might cause crystallization that appears to propogate FTL, but it's not true to say it actually does. $\endgroup$ – Vaelus Feb 22 at 16:23
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    $\begingroup$ @JustinThymetheSecond To be honest, the articles you're citing look very lackluster in terms of scientific rigor. I would dig into the actual papers they're referencing to figure out what they're misinterpreting/exaggerating, but there are zero links to any actual sources and they don't even mention the author names and year. I'm not an expert in this field but I'm fairly certain that the consensus is still that entanglement cannot transmit information (see the no communication theorem). Just disparaging peoples' textbooks while linking pop science articles is not convincing me otherwise. $\endgroup$ – el duderino Feb 22 at 20:25
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    $\begingroup$ @JustinThymetheSecond That article's findings don't imply information is trasmitted FTL. This answer on Physics SE, explains the type of experiment. The authors of the article assume the third interpretation laid out in the answer, and find a lower bound for the speed of the "interaction". The authors aditionally demonstrate their result is independent of orientation. Note that this interaction, if it exists, cannot form crystals in a way that transmits information. The two cases in my answer still hold. $\endgroup$ – Vaelus Feb 23 at 15:31

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