[HN Gopher] Atomic resolution video of salt crystals forming in ...
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Atomic resolution video of salt crystals forming in real time
Author : rbanffy
Score : 634 points
Date : 2021-01-22 18:28 UTC (1 days ago)
(HTM) web link (www.u-tokyo.ac.jp)
(TXT) w3m dump (www.u-tokyo.ac.jp)
| zaroth wrote:
| Truly mind blowing being able to actually see the atoms align in
| an instant and the crystal structure just pop into existence.
|
| Hard to believe it's not a computer model. I mean, I guess
| underneath there must be a hell of a lot of signal processing
| going on to render that video, but atomic-scale video is wild.
|
| Funny that it looks kinda like MPEGS online circa 1990s.
| anthk wrote:
| Also, static from no TV signals on the TV.
| m463 wrote:
| self-organizing static
| mywittyname wrote:
| I also love how you can see the probabilistic nature of
| electron orbitals in action. The crystal fades in and out of
| existence during the early stages of nucleation. And even after
| the structure is established, the boundaries continue to be
| "fuzzy."
|
| Even the movement of the crystal looks like a wave, but I don't
| know if that's because matter moves as a wave at the atomic
| level or if that's just an artifact from the camera.
| jng wrote:
| I would think that the coming in and out of view at the
| beginning is more related to the crystal moving around and
| falling "in and out of focus" (whatever that means for this
| type of camera). I'd love to watch quantum probability wave
| fluctuations, but I think we're still pretty far from probing
| that.
| jtaillon wrote:
| In this case, "in and out of focus" is actually variations
| in the amplitude of the probability function for the
| electron density projected onto a single plane (to a first
| approximation). Sometimes the wave functions of all the
| electrons interfere constructively, so you see a bright
| spot, and sometimes deconstructively, so you see dark.
| Depending on the orientation of things, this results in the
| images of "atoms" that you see in the picture. As the
| crystal changes shape and size, the interference patterns
| change, which partially explains why it disappears and
| reappears a few times. There's a bit more going on than
| that, but the physics of what's happening in a TEM image is
| really neat.
| jng wrote:
| Wow, mind blown. Thanks for correcting me. Amazing to
| learn that the wave function is so directly sampled by
| TEM that the image we get shows Moire patterns caused by
| its phase :)
| gus_massa wrote:
| Most of the electrons in a NaCl crystal are quite
| localized (all the core electrons od Na+ and Cl-, and
| it's not a good conductor, so the valence band is full).
| So I don't expect too much interesting interference
| patterns. It looks like a problem with vibrations that
| make it go out of focus.
| Ericson2314 wrote:
| Per the other comments, I think time scale is far to
| large for that to be the case in any not-also-explained-
| classically sense.
| Osmium wrote:
| > I don't know if that's because matter moves as a wave at
| the atomic level or if that's just an artifact from the
| camera.
|
| Artifact of the imaging, note the time scale of the movie,
| it's much longer than any quantum oscillation. Each
| individual image of the movie is taken eons apart from the
| perspective of the crystal.
| magicalhippo wrote:
| > Each individual image of the movie is taken eons apart
| from the perspective of the crystal.
|
| Given the timescales of atomic reactions, which IIRC is
| typically measured in nano- or picoseconds, this video is
| more like watching galaxies form I suppose.
| WClayFerguson wrote:
| It's almost like a "standing wave" (of the square pattern)
| emerged spontaneously out of a chaotic stew of probability
| waves, and I guess that's a better way to describe quantum
| mechanics at this level than to say "The Na and Cl atoms
| snapped together". Nothing snapped to together. This video
| shows a pattern emerging from pure chaos, all based on
| probabilities and the fact that each individual atom
| probability wave can only oscillate in certain patterns.
|
| I'm pretty sure in Quantum Mechanics systems like this the
| entire unit behaves as one and there's no real distinction
| possible regarding "which is which" if you were to try to
| identify individual atoms. It would be like looking at a
| standing wave pattern in water (or any other medium) and
| labeling one peak "Wave A" and some peak "Wave B". You can't
| really do it. Because for the standing wave pattern to exist
| at all it has to be the entire system interaction to cause it
| to emerge.
|
| I'm not saying atoms are "Standing Waves" but I'm merely
| making an analogy. However even from some perspective you
| could even say any oscillating system of wave probabilities
| when taken as a "system" comprises a standing wave.
| WClayFerguson wrote:
| Not that I'm trying to blow anyone's mind but here's a
| couple of other 'emergent patterns' in reality which can
| also be called standing waves, which proves some very low
| level patterns like DNA can cause identical patterns to
| emerge billions of layers higher in the causal chain of
| reality, and way higher than just the physical structure of
| the body and brain but also into the surrounding world.
|
| https://www.reddit.com/r/BeAmazed/comments/l2mtfx/separated
| _...
| gus_massa wrote:
| > _I 'm pretty sure in Quantum Mechanics systems like this
| the entire unit behaves as one and there's no real
| distinction possible regarding "which is which" if you were
| to try to identify individual atoms._
|
| The grow experiment was at room temperature 298K. At this
| temperature the nuclei of the atoms behave almost
| classically. There are some important quantum effects
| between the electrons, but their mass is like 10000
| smaller. The effects are small in the electrons in the
| lower levels that are close to the nuclei, but in the
| valence band they can be very important. Specially in
| conductors where the electrons are very delocalized, but
| this is not a conductor.
| thaumasiotes wrote:
| > At this temperature the nuclei of the atoms behave
| almost classically.
|
| The video seems to show a crystal made of fairly large
| spheres... which appear from nothing. I don't see a bunch
| of chaotic spheres which arrange themselves into a grid;
| I see a grid of spheres appearing where there was nothing
| before.
|
| I have a hard time thinking this corresponds to classical
| mechanics. :/
| tsimionescu wrote:
| The timescale is relevant. You're seeing 2 frames
| milliseconds apart of a process that took probably a few
| nanoseconds.
| thaumasiotes wrote:
| Why are there any frames in which the sodium and chlorine
| atoms appear not to exist?
|
| Suppose there was just the chlorine (no sodium), and we
| observed it the same way. Would we see mostly chaotic
| arrangements of big spheres, or mostly a smooth
| background with no spheres?
| tsimionescu wrote:
| Because you are seeing frames once every few milliseconds
| of atoms moving back and forth at speeds a fraction of
| the speed of light. It's only when they happen to be in
| very fixed positions that you have any hope to notice a
| definite image of the NaCl molecule.
|
| In general, the very fact that you can see something
| should be a clear indication that you are not observing
| quantum behavior: particles whose properties (such as
| position) are measured DO NOT behave according to
| classical physics, they no longer display quantum
| effects. And while we have yet to understand what exactly
| counts as a measurement, something which allows you to
| have a picture of the atoms certainly counts.
| gus_massa wrote:
| Near the bottom is a figure with some cherry picked
| frames of the video and a handmade drawing showing the
| crystal and the incoming pairs of atoms.
|
| The Brownian motion depends on the mass of the object, so
| the average movement of the individual atoms is higher
| than the average movement of the small crystal. So the
| isolated atoms are blurred in the image.
| WClayFerguson wrote:
| I answered all this in my reply to l33tman, above so I
| won't repeat that here, but check it out.
| WClayFerguson wrote:
| It's not that the individual atoms didn't exist before
| they joined, but it's that they start oscillating in
| unison with each other in a pattern that emerges purely
| from wave interactions.
|
| Nature settles into the most stable patterns of
| oscillation it can find, even without anything "causing
| that". To fully understand this kind of emergence you
| need to realize even the following video is in the same
| category of phenomenology called "emergence":
|
| https://www.youtube.com/watch?v=5v5eBf2KwF8
|
| Atoms themselves "emerge" from probability waves, not the
| other way around.
|
| On a wild tangent: I believe all emergent patterns
| represent "negative entropy" so I claim this disproves
| the Second Law of Thermodynamics, because it fails to
| take into account (i.e. quantify) "pattern-ness" or
| "order" in systems. Total entropy of the universe maybe
| doesn't increase but remains at zero, where the order
| perfectly counterbalances the randomness. Since there's
| no way to "measure" order in a system, the Second Law
| remains somewhat philosophical despite it being
| consistent with 'gross averages' measurements like
| temperatures, pressures, volumes, etc., in classical
| systems for which essentially only one side of the
| equation can be quantified.
| l33tman wrote:
| There is really nothing quantum in this, you can simulate
| this completely classically, although it takes forever as
| it's a slow process, as you seen when you compare the
| timescale of the video in the seconds to the timescale the
| atoms move about, in the femtoseconds.
|
| I'm not a salt nucleation expert by any means, but I'd
| imagine the process has a similar statistics as protein
| folding. Individual folding events (and nucleation events)
| are superfast but takes forever to trigger (a lot of stars
| have to align so to speak). This is why, from just looking
| at frames 1/25s apart, it looks like suddenly things
| appeared out of nothing, but really there were eons of time
| in between the frames in the video.
| WClayFerguson wrote:
| > There is really nothing quantum in this
|
| Even if you consider a Hydrogen atom floating in free
| space a billion miles from any planets, _everything_
| about it is 100% "quantum".
|
| There are no actual electrons going around the nucleus,
| because it's purely just a quantum probability wave. If
| you then introduce Oxygen atoms near it, then the
| probability wave of the two begin to behave as a _single_
| system and will oscillate in a _different_ pattern but
| STILL a single quantum mechanical system, and one big
| "wave function" that represents the entire system.
|
| In this multi-atom system you also cannot even say that
| one specific electron is going around one atom, and
| another electron is going around a different electron
| (the incorrect classical view). The electron probability
| wave for the entire system is one big probability wave
| oscillator function, and both electrons contribute to
| magnitudes of observables in an identical way to each
| other. So the two electrons loose their individual
| identity. They're both part of a 'cloud' but you can't
| say where any of them are. Not because it's hard to
| measure, but because actually _reality itself_ doesn 't
| even know.
|
| None of this is inconsistent with the fact that the
| classical view also holds true under ordinary
| observational conditions, and can be _estimated_ (albeit
| incorrectly) as pre-existing atoms "snapping together"
| by the laws of chemistry, but that is the less 'complete'
| view. Just like Newton is a less complete view than
| Relativity, but still 'works'.
| tsimionescu wrote:
| While the electrons do form a cloud and aren't entirely
| well positioned in space as far as we know, it's
| important to remember that there still are a fixed number
| of electrons which can be detected one by one, even
| though they may interact with themselves or each other at
| multiple positions at the same time before our detection.
|
| Furthermore, it is not yet proven that reality behaves
| the same in classical settings as it does in quantum
| interactions. For all we know, wave function collapse may
| be a physical phenomenon that happens at specific
| conditions, yielding purely classical behavior. Your
| explanation is one popular view of QM, but it is not the
| only possibility that would be consistent with
| observations.
| WClayFerguson wrote:
| > Your explanation is one popular view of QM
|
| If you want to call the "Standard Model" merely one among
| many "popular views" then you can, but that's not what
| I'd call accurate. No one really disagrees with it. They
| just have different "interpretations" of why it holds
| true.
|
| Regarding your claim that electrons "interact with
| themselves", that's actually kind of misleading too. When
| electrons are "in the cloud" (pre-wave-collapse) they're
| pure probability and so none of them have an actual
| location in spacetime even if you had some infinitely
| fast camera to look. They simply don't exist at specific
| locations. They are _genuinely_ everywhere at once, or
| stated even _more_ correctly: they don 't exist. Only the
| energy exists.
|
| The "Bohr Model" of the atom is correct insofar as a way
| to track energies in a classically relevant way, but in
| no way at all is it actually "real". There's no electrons
| flying around. Only electrons that have already stopped.
| They don't exist until measured.
| tsimionescu wrote:
| > If you want to call the "Standard Model" merely one
| among many "popular views" then you can, but that's not
| what I'd call accurate. No one really disagrees with it.
| They just have different "interpretations" of why it
| holds true.
|
| The Standard Model doesn't contain an explanation for the
| measurement problem, which is essentially what your
| explanation is touching on, with the claim that
| everything is quantum and that the electron really
| doesn't have a definite position in space, rather than us
| being unable to know its position. Basically you stated a
| version of the Copenhagen Interpretation, which is very
| popular, but not the only way of making sense of the wave
| function.
|
| > When electrons are "in the cloud" (pre-wave-collapse)
| they're pure probability and so none of them have an
| actual location in spacetime even if you had some
| infinitely fast camera to look. They simply don't exist
| at specific locations. They are genuinely everywhere at
| once, or stated even more correctly: they don't exist.
| Only the energy exists.
|
| I think you're mixing things up a bit here. Before a
| measurement takes place, the movement of electrons is
| predicted by a deterministic equation, there is no
| probability. The electron is indeed (described by?) a
| wave function that has some amplitude at any point in
| space. My point about "interacting with themselves" was
| that the Schrodinger equation predicts the possibility of
| self-interference of a single electron's wave function,
| which is an observed effect.
|
| I think you're also over-selling the wave part of the
| duality and disregarding the particle part. The electron
| doesn't behave entirely like a wave, it also has
| particle-like properties, such as a fixed mass and a
| fixed charge.
|
| > There's no electrons flying around. Only electrons that
| have already stopped. They don't exist until measured.
|
| This is exactly the part that people love claiming as if
| it is settled, when it is anything but. The reality is
| that we don't yet know what quantum particles are. If
| they don't exist until you measure and then they start
| existing, then you need to explain what a measurement is,
| which we have no idea how to.
|
| In fact, even the Copenhagen interpretation doesn't
| exactly say what you are claiming. It is instead claiming
| that the wave function + the Born rule are a mathematical
| tool that predicts the behavior of quantum systems with
| excellent accuracy, and that the probabilities in the
| Born rule are fundamental. If we accept this fundamental
| impossibility of predicting deterministically the
| properties of a quantum system, it follows that it is
| unscientific to claim that the particles "have"
| properties that we fundamentally can't measure. This un-
| existence is then a philosophical argument, not a
| physical one: it's stating that something that can't in
| principle be measured can't be said to exist.
|
| Other popular explanations that are perfectly compatible
| with the Standard Model are:
|
| - the particles are real, and they exist at all positions
| in space as predicted by the Schrodinger equation, but
| these results happen in different universes; for some
| unexplained reason, "classical objects" can only observe
| one world at a time
|
| - particles are real, and their movement is affected by a
| real carrier wave; the particle has a definite but
| unmeasurable location in space and speed, affected by the
| carrier wave; the carrier wave is the wave described by
| the Schrodinger equation
|
| - Measurement is a physical process that causes particles
| to switch from being somewhat indefinite objects
| described by the wave function to being definite objects
| described by classical (rather, relativistic) mechanics
|
| Of course, some of these interpretations have their own
| unintuitive aspects (non-locality), because of the Bell
| inequalities. There is also super-determinism, that could
| in principle allow QM to be both deterministic and local,
| at the cost of statistical independence.
|
| And finally, the Standard Model itself doesn't yet
| account for gravity, and the current theories we have for
| gravity do not work with masses that have indefinite
| positions in space, so there is still room for
| discoveries that could contradict somewhat the
| fundamental properties of "particles" as known today
| (though, to be fair, it is more likely that our theories
| about gravity are the ones that will need adjustment).
| WClayFerguson wrote:
| I can tell you're deep into Physics as I am. To be honest
| I was presenting the "Standard Model" the way a professor
| would explain it to a student, who is trying to explain
| QFT using the conventional beliefs held by most of the
| Physics community.
|
| I agree with everything you said, actually, except for
| this one sentence which you stated which I know is some
| kind of typo, because I doubt you think it's true:
| "Before a measurement takes place, the movement of
| electrons is predicted by a deterministic equation, there
| is no probability." That sentence goes against
| conventional wisdom so I doubt you meant it litterally.
|
| Anyway, if you want my own personal unproven belief
| (theory) here it is: (or a few aspects of it)
|
| I think our universe is a 3D (excluding time) manifold
| that is an event horizon in a larger higher dimensional
| space and what we call "Wave Collapse" is actually the
| point where an actual existing real particle does travel
| across our manifold. That is, anything that we can assign
| a position to in spacetime coordinates is also "on" this
| manifold. You can also call this manifold our "universe".
|
| So when something exists in what we call "Probability
| Wave" state that just means we haven't yet done something
| to pinpoint a particle "on" this (our) event horizon.
| Unless someone is a very good geometry mathematician they
| cannot really comprehend how our entire universe can be a
| "surface" in some a higher-dimensional space, and since
| it's unproven I generally don't bring it up on HN. I also
| believe all N-Dimensional spaces contain
| (N-1)-Dimensional constructs inside them. The example in
| our unsivers is 'black holes'. We see 2D (i.e (3-1)D)
| constructs where our physics fails and even have proven
| their informational content is proportional to surface
| area (Hawking+Susskind). Most people think black holes
| are 3D spheres, but they're really 2D surfaces to their
| "inhabitants". Similarly the higher dimensional universe
| in which our 3D space is embedded would see our universe
| similarly as some kind of construct where their own
| physics breaks down, and they are unable to "look" inside
| possibly, just like we can't see inside black holes.
|
| Also if we are an event horizon it disproves the big bang
| theory. The inhabitants of a black hole would notice
| their "universe" is expanding, and therefore conclude
| they came "from" some center point, but in reality BHs
| form from outside in, not inside out. So our universe
| came from outside itself not inside itself. It doesn't
| solve the 'first mover' problem, it just inverts it, but
| it does simplify it.
|
| All that to say, I appreciated your response and you're
| right I was putting the "professor hat" on when I
| described most of what I said on this thread, but the
| paragraph above should prove I'm capable of as much
| quackery as the next guy. lol.
| tsimionescu wrote:
| Glad we mostly agree :)
|
| > I doubt you think it's true: "Before a measurement
| takes place, the movement of electrons is predicted by a
| deterministic equation, there is no probability." That
| sentence goes against conventional wisdom so I doubt you
| meant it litterally.
|
| I meant that very literally, and it is very important to
| understand. Quantum mechanics contains two fundamental
| postulates:
|
| 1. The Schrodinger equation: any quantum system can be
| described by the Schrodinger equation, which is a linear
| partial differential equation - i.e. it is completely
| deterministic. The solution of the Schrodinger equation
| is one or more wave functions - complex-valued functions
| which have some value for every point in space.
|
| 2. The Born rule: when a measurement is made of the state
| of a quantum system, the probability that a particular
| result will be observed is equal to the square of the
| amplitude of the wave function. To predict the state of
| the system after the measurement, the wave function must
| be updated to have the exact value of the measurement and
| no others.
|
| Without the Born rule, QM is completely deterministic,
| and predicts that particles have multiple positions. This
| prediction is actually correct until you measure
| anything. For an example, let's say you have a particle
| P0 whose wave function has some non-0 amplitude at far
| away locations A and B. Say you also have two other
| particles, Pa and Pb; Pa has amplitude almost 1 at point
| A and 0 elsewhere, while Pb has amplitude almost 1 at
| point B and 0 elsewhere. The positions of both Pa and Pb
| will be affected by the properties of P0. So, P0 was
| essentially in both places at once.
|
| However, if you add detectors for P0 at positions A and
| B, what you will notice two things:
|
| 1. If detector A detected P0, detector B will never see
| it, and vice-versa. The probability for each of them will
| correspond perfectly to the square of the amplitude that
| P0 had at that point.
|
| 2. If detector A detected P0, the position of Pb will no
| longer depend on any property of P0, and vice versa.
|
| So, the measurement changes the wave function of the P0,
| Pa and Pb system. The equation before the measurement is
| deterministic, and the equation after the measurement is
| also deterministic, but the switch from the first one to
| the second is probabilistic.
|
| By the way, an excellent resource on this topic is Sabine
| Hossenfelder's blog, for example this post:
|
| http://backreaction.blogspot.com/2019/10/what-is-quantum-
| mea...
| WClayFerguson wrote:
| We may be getting into semantics but QFT doesn't say
| electrons are even moving. It says there are no particles
| at all anywhere period full stop UNTIL the precise moment
| of measurement. This is the "Measurement Problem". The
| measurement CREATES the particle.
|
| The famous Bell experiment proved that the view of
| quantum mechanics as describing how particles "move" is
| incorrect, because the probability wave is not actually
| describing any movements of any actual particles.
|
| If you think of a single Hydrogen atom floating in space,
| no there is not an electron moving around it. There is no
| electron that exists at all "until" something interacts
| (according to Standard Model) with the wave function and
| causes the wave to collapse and "choose" a place in
| spacetime to materialize an "electron" in and only then
| is there an electron.
| tsimionescu wrote:
| Replying separately to this:
|
| > We see 2D (i.e (3-1)D) constructs where our physics
| fails and even have proven their informational content is
| proportional to surface area (Hawking+Susskind). Most
| people think black holes are 3D spheres, but they're
| really 2D surfaces to their "inhabitants".
|
| I think that is more complicated. From what Susskind
| explains, the current understanding is that black holes
| have a dual nature, similarly to the idea of
| wave/particle duality. Specifically, you can perform
| experiments that would see the event horizon of the black
| hole as a 2D surface which emits Hawking radiation; and
| you can perform experiments which will show the event
| horizon of the black hole is a completely unremarkable
| region of space. Importantly though, there is no way for
| an observer to notice both results, so there is no
| contradiction. The black hole is 1 thing to some
| observers, and 1 different thing to other observers, and
| the two can't even communicate.
|
| Even more specifically, to an observer that will never
| cross the event horizon, the event horizon is a surface
| emitting Hawking radiation. For an observer approaching
| and passing the event horizon, the event horizon emits no
| radiation and is a completely unremarkable region of
| space-time. The two observers of course can't
| communicate, as the observer crossing the event horizon
| will never be able to send a signal outside again, and
| conversely, a signal sent from outside after they crossed
| the horizon will never reach them.
|
| I would also note that our current theories do not permit
| any kind of structure to exist "inside" a black hole,
| which is a 0-volume point. If you mean "inside the radius
| of the event horizon of a black hole", I believe matter
| would be observed falling quickly towards the center. A
| theory of quantum gravity may give us some idea of the
| structure of a black hole, but I personally doubt that it
| could be allowed to contain another universe.
| soulofmischief wrote:
| Quantum Field Theory has a lot of strong evidence, as
| does the Copenhagen interpretation of QM, but it might be
| more suitable not to speak of these things as if they are
| 100% fact. It's theory, and it's likely that the eventual
| bridge between QM and classical physics will usher in an
| entirely new model unlike either individual model.
| WClayFerguson wrote:
| I always refer to QFT + Standard Model as 'fact' even
| though myself and all other Physicists agree there may be
| deeper understandings than what is currently known by
| science.
|
| At some point is becomes philosophy when you call into
| question something that has zero evidence against it and
| the evidence in favor of it has been measured out to 43
| decimal places already.
| gus_massa wrote:
| [Replying here as you suggested in the other comment.]
|
| The balls in a pool table are 100% quantum, but they are
| approximated very accurately by Classic Mechanics.
|
| At this level, the position of the nuclei can be
| approximated to move classically, and the electrons
| quantically. Moreover, the standard trick is to
| approximate that the nuclei doesn't move, and then
| calculate the distributions of the electron with quantum
| mechanics. https://en.wikipedia.org/wiki/Born%E2%80%93Opp
| enheimer_appro...
|
| Once you calculate the distribution of the electrons
| assuming the nuclei are at different positions, you can
| approximate an effective force between the nuclei and
| calculate how they move almost like classic objects.
|
| The calculation is too difficult, and the other nearby
| atoms affect them, so there are a lot of approximations.
| For big system, you need to use something like https://en
| .wikipedia.org/wiki/Born%E2%80%93Oppenheimer_appro...
| that approximate the force between the atoms, with some
| formulas that hide all the quantumness and then move as
| if they were classic objects.
|
| So it's a quantum system, like everything in this word.
| But the apparent atoms that appear and disappear are not
| explained by weird quantum effects. They can be explained
| with the simplified classic model when the camera takes
| too few frames, the objects are moving too much, and the
| background is too noisy.
| WClayFerguson wrote:
| I'm glad we agree that classical mechanics accurately
| predicts macro objects.
|
| However, atoms, molecules, and even molecular lattices
| containing a small number of atoms (or large number
| actually), behave as quantum wave systems. Even the link
| you gave states that 'benzene' despite having 42
| electrons, has a _single_ wave function that determines
| probabilities for where an electron can be observed (but
| not WHICH electron. There is no WHICH ELECTRON in the
| function). In that wave function it means there 's no
| longer 42 actual electrons that even exist. There is
| nothing but a probability of where you'd find one if you
| collapse the entire wave simultaneously by taking a
| measurement of any part of it.
|
| When atoms join into a crystal formation that becomes
| even a 'higher level' new emergent pattern of vibrating
| probabilities, that's more complex and structured than
| what the individual particles exhibited before the new
| pattern emerged.
|
| You think I'm wrong to say atoms pop into existence?, but
| we know for a fact all particles are merely probabilities
| until observed. All observation is synonymous with wave-
| collapse, and only upon wave-collapse do you have actual
| particles with actual positions in spacetime. Every
| 'frame' of every video you could ever create is a
| snapshot of "a series of collapses", because that
| collapse is what created the particles that make up the
| 'image' itself.
| tsimionescu wrote:
| You are taking a mathematical formalism and giving it a
| physical meaning, in a way that doesn't make any sense.
|
| The wave function is a way to describe the physical
| properties of an entire system - position, velocity, spin
| etc, for every component that you chose to model (e.g.
| electrons and nuclei, or electrons and protons and
| neutrons, or electrons and quarks etc). To get an
| accurate prediction, you need to input all of the
| relevant parts of the system. For example, when solving
| the Schrodinger equation for a hydrogen atom, people
| input the properties of the electron and proton. If you
| want to compute the properties of a benzene molecule, you
| input information about all of the 6 nuclei and 42
| electrons. If you want to compute the wave function of a
| mole of benzene, you would have to input the properties
| of all ~10^23 atoms composing it. This has no physical
| meaning per se - this is just the nature of the
| formalism.
|
| Depending on the exact system, you may or may not have
| separate components of the wave function which correspond
| to the different components of the system which you are
| modelling - such as a component indicating the position
| of the electron and a component for the position of the
| nucleus/proton for the Hydrogen atom.
|
| Also, if you were to model an electron launched towards a
| benzene molecule, the wave function of the system would
| show different values for the 1 electron that was
| launched vs the 42 electrons which were part of the
| original system.
|
| The 42 electrons are not distinguishable simply because
| we don't normally choose to input any way of
| differentiating them, because we don't think it's useful.
| You could in principle describe the system such that you
| get a particular prediction for each of the 42 different
| electrons - though we don't know any property that
| electrons have that we could use to actually measure and
| confirm.
|
| > In that wave function it means there's no longer 42
| actual electrons that even exist.
|
| The 42 electrons absolutely exist as part of the wave
| function - otherwise, the charge of the system would be
| wrong. The wave function in fact predicts positions and
| velocities and spins for 42 electrons, and you could in
| principle do a measurement where you would identify the
| positions for all 42 of them, with probabilities that you
| can compare to the wave function predictions.
| WClayFerguson wrote:
| Seems like you're mixing a lot of classical mechanics
| concepts into your 'understanding' of QM. Even in a
| single water molecule the electrons loose their
| "identities" and even if you could look close enough at
| infinitesimally small time intervals at the molecule
| you'd never be able to say "There's one electron here,
| and there's the other over there". And I'm not saying
| it's just too hard to have a microscope that good, I'm
| saying not even "Mother Nature Herself Knows them apart"
|
| Imagine if you setup a standing wave on a water surface,
| and there are exactly two peaks in the wave system. You
| cannot label one "Wave A" and the other "Wave B" and then
| turn off the energy source and then turn it back on and
| create the pattern again and say "Ok now which is A and
| which is B". The question itself is nonsensical. The same
| thing is going on in physics probability waves. Particles
| don't have identities just because "when you look for one
| you find one".
|
| People think QM is describing "where particles go". It
| isn't. It describes where they can be found, and there's
| a huge leap of knowledge in understanding to comprehend
| the difference.
| noneeeed wrote:
| I find a lot of the science being done at the moment truly
| astonishing, the precision and scale of many of the
| measurements being made are mind-blowing.
|
| The sensitivity of instruments like LIGO is hard to get your
| head around.
| kvakkefly wrote:
| You may also like my paper " Direct Atomic Simulations of Facet
| Formation and Equilibrium Shapes of SiC Nanoparticles"
|
| Not as cool as experiment of course
|
| https://pubs.acs.org/doi/full/10.1021/acs.cgd.9b00612
| blix wrote:
| This is a neat paper. Cool to see kinetic phenomena make it's
| way into MD. How many GPU-hours did you need to get those 500ns
| simulations?
|
| You should throw up some videos of these somewhere, if you have
| the time.
| peter_d_sherman wrote:
| _Star Trek 's Replicator -- version 0.000001..._ <g>
| vhold wrote:
| There are video files here :
| https://pubs.acs.org/doi/10.1021/jacs.0c12100?goto=supportin...
| fantod wrote:
| This is super cool but who's idea was it to feature the video as
| a pretty small gif on the side of the page?
| codezero wrote:
| literally every grad student in science fields - they don't
| care about video compression or download quality - and gifs are
| fast and easy to make and simple to grok and come out with
| straightforward and predictable fidelity.
| anthk wrote:
| webm's are smaller and ffmpeg can convert any gif in a
| breeze.
| codezero wrote:
| They don't care, and their PI will find a way to complain
| about it not playing on Word '97.
| at_a_remove wrote:
| Still cannot look at an embedded .webm on my iPad in
| Firefox.
| mvanga wrote:
| Can anyone more knowledgeable comment on the details and
| significance of the comment regarding the frequency of formation
| being a normal distribution?
|
| > Straight away, they noticed a statistical pattern in the
| frequency at which the crystals emerged; it followed what's known
| as a normal distribution, which has long been theorized but only
| now experimentally verified.
| blt wrote:
| I am also wondering about this. Normal distributions have
| support on all real numbers, which would imply that negative
| frequencies have nonzero probability. That is strange. Perhaps
| the underlying mechanism is more faithfully modeled by another
| distribution with nonnegative support, but due to the central
| limit theorem it is well-approximated by a normal distribution.
| [deleted]
| jasondclinton wrote:
| Non-physicist question: why does the block of the forming crystal
| move as a whole back and forth? Is this Brownian motion in
| action?
| magicalhippo wrote:
| The containing structure (the carbon nanohorn as they call it),
| is vibrating. So I'm guessing it's getting kicked around when
| it touches the walls, so to speak.
| hindsightbias wrote:
| Guessing the crystals are probably connected in some lattice so
| won't move independently. The expansion horizontally is gated
| by the walls so it gets bounced around until it moves to a
| wider section. There seems to be some ratio of horizontal vs
| vertical growth.
| jagraff wrote:
| This is incredibly cool:
|
| > Two novel techniques, atomic-resolution real-time video and
| conical carbon nanotube confinement, allow researchers to view
| never-before-seen details about crystal formation. The
| observations confirm theoretical predictions about how salt
| crystals form and could inform general theories about the way in
| which crystal formation produces different ordered structures
| from an otherwise disordered chemical mixture.
|
| > To hold samples in place, we use atom-thick carbon nanohorns,
| one of our previous inventions. With the stunning videos
| Sakakibara captured, we immediately noticed the opportunity to
| study the structural and statistical aspects of crystal
| nucleation in unprecedented detail.
|
| Creating shaped nucleation sites using carbon nanotubes
| (nanohorns?) sounds like a fascinating technology. I don't have
| access to the paper unfortunately - I'm curious what other types
| of crystals could theoretically be grown with this technology.
| The authors mention graphite - what about silicon? Could it be
| used to grow more regular crystals for use in electronics? With
| fewer defects, I'd imagine we could reduce the failure rate in
| manufacturing.
| grishka wrote:
| > I don't have access to the paper unfortunately
|
| The website you're looking for starts with sci and ends with
| hub.
| sebmellen wrote:
| Not up there yet. Probably needs a few weeks, unless a HN
| reader is so kind as to add it: https://sci-
| hub.se/10.1021/jacs.0c12100.
| [deleted]
| [deleted]
| MizelMiser wrote:
| Here's the paper
| https://www.scribd.com/document/491808551/jacs-0c12100
| Ericson2314 wrote:
| Are you angling for some scintillating chub?
| [deleted]
| codercotton wrote:
| Super cool, where's my replicator?
| curtainsforus wrote:
| Just build your own
| krylon wrote:
| The trivial task of building a working replicator is left as an
| exercise to the reader. ;-)
| [deleted]
| acvny wrote:
| I can't see the video. Incredible that the actual appearance of
| the crystal happens in phase transition - almost instantly.
| tomsmeding wrote:
| Direct link to a higher-framerate video than the gif on the
| linked page:
| https://pubs.acs.org/doi/suppl/10.1021/jacs.0c12100/suppl_fi...
| convery wrote:
| It's shit like this that makes me re-consider the simulation
| argument, like how statistics is just an optimization to save
| compute power.
| enchiridion wrote:
| In which direction?
| bearerofgarbage wrote:
| https://en.wikipedia.org/wiki/Falsifiability
| thepace wrote:
| Every time I see these kinds of video, whether that is of protein
| translation, kinesin walking on microtubule, or birth and death
| of a galaxy, I get this feeling that Panpsychism is closer to
| truth that it gets credit for. Any constraints we put in the
| defining consciousness and life seems to be just some arbitrary
| constraint put there for our own convenience.
| wahern wrote:
| Panpsychism, pantheism, etc, are enticing because humans are
| predisposed to see patterns, structure, reason, and
| intelligence; to anthropomorphize nature. Characterizing as
| "arbitrary" our admittedly feeble and flawed attempts at
| distinguishing the human mind is an easy way to placate that
| underlying, intrinsic desire.
|
| Of course, maybe it is true! (That felt good to say :)
| TeMPOraL wrote:
| Isn't panpsychism a kind of reverse materialism? Both seem to
| correctly recognize that terms we create are just lines we draw
| on our map through the terrain of reality, which we rank by
| their usefulness, by how close they seem to be "carving nature
| at its joints". Based on my brief skimming, panpsychism seems
| to say the terrain is all mysterious and wonderful, whereas
| materialism says it's all just mundane.
|
| Or am I completely mis-skimming the Wikipedia entry on
| panpsychism?
| perfmode wrote:
| my question to you: do you consider yourself to be mysterious
| or just mundane? what is your experience of your own Being-
| ness?
| TeMPOraL wrote:
| A good question, something I'll have to think about.
|
| The immediate if indirect answer I can give you: I stopped
| feeling this sense of wonder, mystery, greater purpose of
| reality, somewhen during my university years. I only ever
| experience these feelings when consuming works of fiction.
| mensetmanusman wrote:
| C.S. Lewis described something similar with fiction
| 'baptizing the imagination in longing'
|
| https://andrewmarrosb.blog/articles/baptizing-the-
| imaginatio...
| gus_massa wrote:
| > _Do you consider yourself to be mysterious or just
| mundane?_
|
| Mundane, that is even more amazing.
|
| > _What is your experience of your own Being-ness?_
|
| My electrons and nuclei are arranged in a weird pattern. If
| you ask them if I'm conscious, they can move another
| electrons and nuclei to type "yes". If you ask them if I'm
| lying, they can move another electrons and nuclei to type
| "no". It's just a strange pattern that simulates a
| delusion, don't trust them.
| perfmode wrote:
| > Mundane, that is even more amazing.
|
| What's amazing about the mundane?
| lewispollard wrote:
| I think you'd enjoy the work of Bernardo Kastrup, who is a
| proponent of idealism, while also arguing against
| panpsychism, for basically the reasons you just stated - ie,
| there is a reality made of parts, and those parts are x,
| where x is 'matter', 'mind', 'consciousness',
| 'electromagnetism' and so on. But the trouble then is that
| you can only describe the constituent parts in terms of those
| parts. For example, subatomic particles have properties like
| spin and charge, but that's the only way you can describe
| them - in relation to one another - without having to go a
| level 'deeper' if it were possible to describe them in
| further parts (which would only be describable in terms of
| those parts, and so on).
| csomar wrote:
| > Any constraints we put in the defining consciousness and life
| seems to be just some arbitrary constraint put there for our
| own convenience.
|
| The definition of consciousness is very much tied to how humans
| (or some scientists) perceive consciousness. I'm pretty sure my
| dog is conscious of itself and its surrounding. It just happens
| to have a less sophisticated consciousness than the one I have.
| Some animals might have a pretty high consciousness but they
| fail to communicate it to the humans.
| kharak wrote:
| I can't see this connection at all. Could someone who thinks or
| feels this way elaborate?
|
| Does this feeling arise because those atoms move? Or is it the
| self-assembling behavior? Is this the same feeling some people
| have when they see a door suddenly close due to the wind, as if
| some spirit is responsible? I remember feeling like this as a
| kid. But getting older, I realized that this feeling of agency
| behind everything is unfounded. And the feeling faded away.
| jes wrote:
| I am an Alan Watts fan. I think he would agree with you.
| djedr wrote:
| He would definitely dig that. Curiously, I was drawn to this
| thread because I was just listening to him today, talking
| about crystals and the nature of reality. He would go thru so
| many topics in such detail and clarity, it's incredible.
| jes wrote:
| Same. I often notice the precision with which he used
| language. Such a joy to listen to.
|
| I especially like the chill-step YouTube videos some people
| assemble and publish. I download them with youtube-dl and
| listen to them on my phone at night while drifting off to
| sleep.
|
| At 61 years of age, the philosophy he describes (Advaita
| Vedanta / Zen Buddhism / Taoism) brings me great comfort.
| thepace wrote:
| Out of the many people I have heard talk about vedanta,
| Alan Watts is one of the most original ones.
| djedr wrote:
| > I often notice the precision with which he used
| language.
|
| Indeed. Hard to find an inaccuracy, even when he's
| talking about some details of technical subjects. He had
| an exceptional ability to translate between the spiritual
| and the technical in a way which seems to make complete
| sense.
|
| > Such a joy to listen to.
|
| A true spiritual entertainer. Never boring. I imagine he
| could be a stand-up comedian today.
|
| > I especially like the chill-step YouTube videos some
| people assemble and publish. I download them with
| youtube-dl and listen to them on my phone at night while
| drifting off to sleep.
|
| Similar, I went thru a lot of the material on youtube.
| High-quality material with transcripts can also be found
| here: https://www.organism.earth/library/author/alan-
| watts A lot of it I listened to many times over and I
| keep getting new insights out of it, it's so densely
| packed.
|
| > At 61 years of age, the philosophy he describes
| (Advaita Vedanta / Zen Buddhism / Taoism) brings me great
| comfort.
|
| Definitely helps to know these philosophical
| perspectives, especially if one gets tangled up in some
| harmful model of reality.
|
| Somehow the basic (non-religious, just philosophical)
| Taoism seems to most align with me at the moment. I
| credit the Dao for solving a very tough naming problem
| for me. ;)
| jng wrote:
| I love Alan Watts too. In any case, I need to insert the
| necessary reference to recently passed John Conway's Free
| Will Theorem. I recommend every one to watch his 6-lecture
| long presentation on this, available on YouTube and
| underappreciated given the number of views, where he
| captivatingly describes his proof that, if we have free will,
| so do elementary particles. This is a purely mathematics- and
| physics-based proof which I understand is fully accepted by
| the scientific community, and while it, of course, does not
| provide an explanation of the underlying cause, it provides
| the best possible description obtained by scientific
| methodology so far.
|
| I like to think that, somehow, Alan Watts and John Conway
| were digging the same tunnel, just starting from the two
| endpoints, and bound to meet at some point in the future. We
| just need a few more diggers of that stature (tall order, I
| know).
| jes wrote:
| Paper from Anthony Cashmore that I mentioned previously:
|
| https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2842067/
| jes wrote:
| Thank you for this reference. I'm a free will skeptic. Now
| looking forward to watching Conway's series.
|
| I have a paper by Anthony Cashmore that I will cite here
| later.
| [deleted]
| anthk wrote:
| Is there a way to watch the video without JS?
| zer0n1ght wrote:
| Just like a bunch of sphere magnets.
| amelius wrote:
| Why are the atoms not visible when they are still in dissolved
| state?
| jcims wrote:
| I'm curious how they managed to make it happen so slowly. If that
| crystal had grown to 100 molecules in 10 seconds it would take
| roughly the age of the universe to form a grain of table salt.
| jacquesm wrote:
| The growth rate is proportional to the surface area.
| goalieca wrote:
| They confined the reaction to a tiny horn.
| dragontamer wrote:
| > "Salt is just our first model substance to probe the
| fundamentals of nucleation events," said University Professor
| Eiichi Nakamura. "Salt only crystallizes one way. But other
| molecules, such as carbon, can crystallize in multiple ways,
| leading to graphite or diamond. This is called polymorphism and
| no one has seen the early stages of the nucleation that leads to
| it. I hope our study provides the first step in understanding the
| mechanism of polymorphism."
|
| I'm amused that Chemists / Physicists also have the word
| "Polymorphism" and that it means something completely different
| from the programming term.
| flobosg wrote:
| It's also a term used in biology:
| https://en.wikipedia.org/wiki/Polymorphism#Biology
| louthy wrote:
| > I'm amused that Chemists / Physicists also have the word
| "Polymorphism" and that it means something completely different
| from the programming term.
|
| Seems like a good reason to stop using it [in programming], and
| the technique behind it.
| skulk wrote:
| My second confrontation with the term "polymorph" was a Java
| tutorial, the first was Larn
| (https://larn.fandom.com/wiki/Spells)
| MereInterest wrote:
| In some ways, they are sort of related. In chemistry, you have
| different representations (diamond/graphite) of the same
| underlying thing (carbon). In programming, you have different
| representations (PointXY/PointRTheta) of the the same
| underlying concept (Point2D).
| jxramos wrote:
| right, the roots of the word make it applicable to lots of
| stuff, poly or many, morph or structure/form.
| adrianmonk wrote:
| Arguably it's the strategy pattern. Graphite and Diamond
| are subclasses of CrystalizationStrategy.
| iainmerrick wrote:
| Things could get messy real fast if you need to inherit
| from both Graphite and Diamond...
| frumiousirc wrote:
| Yes, the diamond inheritance pattern is a classic OO
| problem. :D
| chrisweekly wrote:
| Favor composition over inheritance!
| LightMachine wrote:
| That isn't what polymorphism means, polymorphism would be
| more like Point<Float> and Point<Double> using the same Point
| definition.
| soheil wrote:
| This looks like how microscopic proteins and bacteria move in the
| body. I wonder how much of their motion is caused by the atomic
| level forces that form a lattice structure similar to that of
| salt crystals.
| rightbyte wrote:
| The "tube"/horn is vibrating. I would make that connection from
| the gif. The scale difference is quite big.
| adrianmonk wrote:
| Amazing achievement! Not only the world's first video of this
| type, but I imagine also the world's smallest salt shaker.
| dylan604 wrote:
| A salt shaker that makes its own salt to boot! Never run out of
| salt again with our new patented shaker! Just $19.99 if you buy
| within the next 15 minutes. Order now, and we'll also throw in
| the matching pepper shaker (not self re-filling) for free!
| (just pay S&H for both)
| biggio wrote:
| Hope this will help finding a way to dissolve calcium oxalate
| stones formed in kidney
| edumucelli wrote:
| Amazing! Also kudos to the master student that, although starting
| his career in science, already actively participated in this
| incredible work!
| overdrivetg wrote:
| This was a cool AlphaPhoenix video doing a large-scale crystal
| growth simulation that looks amazingly similar:
|
| https://youtu.be/06TscuHNvGQ?t=305
| [deleted]
| frongpik wrote:
| Another interesting experiment is the effect of strong magnetic
| fields on crystals: when the field is turned off, is there
| something left in the crystal, e.g. a certain motion pattern of
| crystal nodes?
| jerzyt wrote:
| What is absolutely mind blowing to me is that when I was in
| college, in my crystallography class, we were inferring the
| crystal structure through the X-ray diffraction. Now we can
| observe it directly. I took the crystallography class in late
| 70s. I doubt that anyone had expected so much progress.
| 6nf wrote:
| In the same vein, I'm blown away what we can do with xray
| crystallography these days! Structures of proteins with
| hundreds of atoms can somehow be deduced from some tiny light
| spots in a kaleidoscope picture? Magical.
| bearerofgarbage wrote:
| Could one be able to upscale the video with a GAN like the
| following example?
|
| https://www.geoffreylitt.com/images/article_images/enhance/g...
| Bjartr wrote:
| I'm pretty sure such upscaling systems train against ground
| truth higher res video and purposefully downres'd versions of
| that video. So, at the very least, we'd need to first get
| higher res video of the same phenomena once. Though maybe you
| could style transfer from frames that have been improved by
| hand.
| dannyw wrote:
| One could, but it wouldn't be real.
| bearerofgarbage wrote:
| All models are wrong, some are useful
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