Catch up on stories from the past week (and beyond) at the Slashdot story archive

 



Forgot your password?
typodupeerror
×
Science

Atoms Aren't Empty (aeon.co) 187

Kitty Oppenheimer: Can you explain quantum mechanics to me?

J. Robert Oppenheimer: Well, this glass, this drink, this counter top, uhh.. our bodies, all of it. It's mostly empty space. Groupings of tiny energy waves bound together.

Kitty Oppenheimer: By what?

J. Robert Oppenheimer: Forces of attraction strong enough to convince us [that] matter is solid, to stop my body passing through yours.


IMDB quote from Oppenheimer


Flash forward to 2023, where Mario Barbatti is a theoretical chemist and physicist researching light and molecule interactions. He's also a professor of chemistry at Aix Marseille University in France. Writing this week for Aeon, Barbatti argues that "there are no empty spaces within the atom.

"The empty atom picture is likely the most repeated mistake in popular science." It is unclear who created this myth, but it is sure that Carl Sagan, in his classic TV series Cosmos (1980), was crucial in popularising it. After wondering how small the nuclei are compared with the atom, Sagan concluded that "[M]ost of the mass of an atom is in its nucleus; the electrons are by comparison just clouds of moving fluff. Atoms are mainly empty space. Matter is composed chiefly of nothing." I still remember how deeply these words spoke to me when I heard them as a kid in the early 1980s. Today, as a professional theoretical chemist, I know that Sagan's statements failed to recognise some fundamental features of atoms and molecules...

Misconceptions feeding the idea of the empty atom can be dismantled by carefully interpreting quantum theory, which describes the physics of molecules, atoms and subatomic particles. According to quantum theory, the building blocks of matter — like electrons, nuclei and the molecules they form — can be portrayed either as waves or particles. Leave them to evolve by themselves without human interference, and they act like delocalised waves in the shape of continuous clouds. On the other hand, when we attempt to observe these systems, they appear to be localised particles, something like bullets in the classical realm. But accepting the quantum predictions that nuclei and electrons fill space as continuous clouds has a daring conceptual price: it implies that these particles do not vibrate, spin or orbit. They inhabit a motionless microcosmos where time only occasionally plays a role...

A molecule is a static object without any internal motion. The quantum clouds of all nuclei and electrons remain absolutely still for a molecule with a well-defined energy. Time is irrelevant... Time, however, comes into play when a molecule collides with another one, triggering a chemical reaction. Then, a storm strikes. The quantum steadiness bursts when the sections of the electronic cloud pour from one molecule upon another. The clouds mix, reshape, merge, and split. The nuclear clouds rearrange to accommodate themselves within the new electronic configuration, sometimes even migrating between molecules. For a fraction of a picosecond (10-12 seconds or a billionth of a millisecond), the tempest rages and reshapes the molecular landscape until stillness is restored in the newly formed compounds.

This discussion has been archived. No new comments can be posted.

Atoms Aren't Empty

Comments Filter:
  • by bugs2squash ( 1132591 ) on Saturday August 26, 2023 @11:55PM (#63800548)
    How is Rutherford's experiment explained then ?
    • Re:foiled again (Score:5, Insightful)

      by Waffle Iron ( 339739 ) on Sunday August 27, 2023 @12:21AM (#63800576)

      How is Rutherford's experiment explained then ?

      Well, Rutherford's experiment had a person *looking* at the atoms. TFS says you're not allowed to look.

      Quantum wave functions may have static solutions spread out in space. However, the essential property of these functions is that they merely describe the probability of locating a particle at any given location with an observation. IMO deciding whether saying the wave function is a physical thing that takes up space, verses saying that it is nothing more than a mathematical abstraction, is a matter for philosophers to ponder while gazing at their navels.

      • Re:foiled again (Score:5, Informative)

        by locater16 ( 2326718 ) on Sunday August 27, 2023 @02:12AM (#63800676)
        That's just repetition of other people saying the same argument. It's the same mistake that makes people think atoms are "empty space". It's a matter for philosophers, this sounds like a smart statement that brooks no counterargument.

        But quantum physics doesn't work, and we know it doesn't work. How on earth does a planck length work if space is continuous as in General Relativity. How does GR work if doesn't describe quantum mechanics?

        The answer is clearly "we don't know" and it's ok to have that as answer. It's better than pretending we do know and that if others were just "smart enough" they'd understand how it's handwaved away by quoting someone else that doesn't know either.
        • Re:foiled again (Score:5, Insightful)

          by Sique ( 173459 ) on Sunday August 27, 2023 @02:31AM (#63800692) Homepage
          With quantum physics, we can calculate the results of experiments up to 15 places and more, and we can measure the results of the experiments up to 15 places and more. We simply don't know where the error lurks, if there is any error at all. We can calculate the atom as if it was empty space, and the results will totally match what we observe.

          The problem is not that quantum physics does not work. The problem is that quantum physics works, and we are pretty sure it shouldn't.

          • Re: foiled again (Score:4, Insightful)

            by blue trane ( 110704 ) on Sunday August 27, 2023 @03:05AM (#63800728) Homepage Journal

            Depending on the Planck energy cutoff and other factors, the quantum vacuum energy contribution to the effective cosmological constant is calculated to be between 50 and as much as 120 orders of magnitude greater than observed,[1][2] a state of affairs described by physicists as "the largest discrepancy between theory and experiment in all of science"[1] and "the worst theoretical prediction in the history of physics".

            What was that about accuracy to fifteen decimal places, again?

        • Re: foiled again (Score:5, Informative)

          by jcochran ( 309950 ) on Sunday August 27, 2023 @05:33AM (#63800912)

          As regards the planck length, you're demonstrating a common fundamental error. The planck length is the smallest measurable length, not the smallest possible length. There is a difference between the two. If you look at how we make measurements at small scales, you'll see why. Use light for example, with visible light our measuring ability is limited by the wavelength of the light used. Want to measure to greater accuracy? Decrease the wavelength and hence increase the energy. So use ultraviolet, x-rays, gamma etc. To measure smaller and smaller distances, we need to focus more and more energy into smaller volumes. Given the equivalency between matter and energy, at the planck length, the amount of energy required (and hence mass) produces a black hole that immediately decays. Adding even more energy does not increase the resolution of the measurement, it merely creates a larger hole with more uncertainty. So remember, the planck length is not the smallest possible distance. It is the smallest measurable distance.

          • by Anonymous Coward

            If you don't teach, consider it. This is a well-written and fascinating explanation.

        • Re:foiled again (Score:5, Insightful)

          by Immerman ( 2627577 ) on Sunday August 27, 2023 @10:08AM (#63801236)

          It seems far more likely to me that it's GR that doesn't work.

          Consider:

          Standard model of QM: extensively tested in the lab, and *every* prediction thus far has turned out to be 100% accurate. There's constantly new papers published about "new forces may have been discovered", a.k.a. experiments don't seem to align with predictions... but to date EVERY one has eventually proven to be just an anomalous data spike.

          GR - explained the anomalous precession of Mercury's and correctly predicted that gravity can bend the path of light, and the gravitational time dilation we measure around Earth... but EVERY prediction it has made at the galactic or larger scales has disagreed wildly with observations, to the point that it requires that over 90% of the mass in the universe must be things we've never seen any other evidence of.

          Of the two, there's FAR more reason to expect that it's gravity we don't understand correctly.

          • Re:foiled again (Score:4, Informative)

            by idji ( 984038 ) on Sunday August 27, 2023 @01:10PM (#63801574)
            I think you're forgetting about some important stuff about GR and the real universe. LIGO has shown spectacular application of GR for neutron star merger, massive glack holes etc. Gravitational lensing is teaching us a lot about Dark Matter itself. GR has demonstrated astounding predictive and quantifiable alignment with the megascale of the universe, not just your observation of Mercury that has more than 100 years ago. So far, it seems to me, *every* predication of GR has turned out to be 100% accurate. Can you name me a single counter-example? Maybe they were also anomalous data spikes.
          • Of the two, there's FAR more reason to expect that it's gravity we don't understand correctly.

            Yet.

      • Re:foiled again (Score:5, Informative)

        by quenda ( 644621 ) on Sunday August 27, 2023 @04:35AM (#63800818)

        To quote Monty Python: "It's only a model."

        In the particle model, it is empty if you can fire a particle though without hitting anything, as Rutherford showed.
        In QM, "empty" isn't really a meaningful concept.

        • by ceoyoyo ( 59147 )

          This story isn't even a model. It's an interpretation, and kind of a fringe one, of a model.

      • However, the essential property of these functions is that they merely describe the probability of locating a particle at any given location with an observation.

        Not so. Many experiments, starting with the two slit, but many far more ornate and definitive on the issue, show that the particle is only a particle when interacting in certain ways. So long as you're not measuring it in those ways, it *is* a wave, and can do many things that particles cannot. And as a wave it can meaningfully be said to simultaneously fill the entire volume occupied by its wavefunction. That's why experiments like the Elitzur-Vaidman bomb tester let you discover definite information a

        • However, the essential property of these functions is that they merely describe the probability of locating a particle at any given location with an observation.

          Not so. Many experiments, starting with the two slit, but many far more ornate and definitive on the issue, show that the particle is only a particle when interacting in certain ways. So long as you're not measuring it in those ways, it *is* a wave, and can do many things that particles cannot. And as a wave it can meaningfully be said to simultaneously fill the entire volume occupied by its wavefunction. .

          There was a paper titled *Anti-Photon* published [Appl. Phys. B 60, 77-84 (1995), W. E. Lamb, Jr.] that argued that the idea the photons were particles at all was false and that only QM fields exist. According to this paper a "photon" is only a unit of energy measured when it is exchanged in some fashion. He does not address Compton scattering though, which seems to show that photons-as-particles definitely exist, so I am not convinced he has the subject nailed down. He may just be leaving out the stuff tha

      • How is Rutherford's experiment explained then ?

        Well, Rutherford's experiment had a person *looking* at the atoms. TFS says you're not allowed to look.

        Yeah, and I'm an incredibly good looking person. A solid 10. Handsome face with beautiful, sensitive eyes and a solid square jaw, and a totally ripped body: Michelangelo could not have carved a more beautiful specimen. But only if you don't look.

      • In quantum theory, the act of observation or measurement causes the wave function to collapse and forces a quantum system into a definite state. This interaction between quanta can occur independently of human observation.

        Using "measuring" rather than "looking" detaches the concept from anthropocentric implications and emphasizes that quantum phenomena arise from quanta interacting at the quantum scale.

    • Well, continuing the summary's analogy: If you shoot a macroscopic gun at a macroscopic water cloud then you expect your bullets to pass right through. If inside the cloud there's a little metal ball then your bullets might occasionally bounce off of it, just like Rutherford's alpha particles. But even though the bullets pass through the cloud, that doesn't mean that nothing's there. The cloud is still there.

      That said, a water cloud is essentially evenly distributed. Electron clouds do have voids, they h
      • What is an electron hole?

        • What is an electron hole?

          Something like this [explainxkcd.com].

          • That's a different thing. I wasn't talking about holes, I was talking about nodes [chemicool.com]. But, because the 1s orbital doesn't have any nodes, technically there shouldn't be any place where the electron cloud density is literally zero.
            • The post said: "The cloud is still there."

              But what if the electron cloud has moved on, i.e., what if there is only an electron hole there?

              • Holes are something else. The electron cloud doesn't move, it's not really a cloud at all. If you think of the electron in the classical sense, the cloud represents all of the places where it could be in the atom. With a certain distribution: the electron is not equally likely to be in all locations in the cloud. Nodes are places where the probability goes to zero.

                In the quantum sense, the electron is not in any one location within the cloud. Rather, the cloud represents the potential location of the ele
        • When an electron is bumped out of position, that position screams for another electron. It's a positive charge called a "hole."

          Holes flow. When an electron fills a hole, it leaves another hole somewhere. This goes on until an atom reaches equilibrium, as in powering off the electron/hole flow.

      • An interesting model of mass is as the curvature of space. In the usual 2d illustration with a rubber sheet representing empty space, you can imagine pinching the rubber sheet with your fingers. The pinch IS the particle. But obviously also there's nothing there, just some scrunched up rubber. So a particle is both empty space and also a spatial obstruction. If you pull on the rubber you see that there is a strong "presence" near the pinch, but it weakens out over larger distances.

        Think of your cloud of m

        • How is this different from Aether theory?

          • The aether was a Euclidean/Galilean space medium relative to which the particles and waves were evolving. What I described is an elementary analogy for the 4 dimensional spacetime. The pinches are high curvature points, that is what mass and particles are equivalent to under the Einstein field equations. In this picture, atoms are basically empty on the outside, and also empty on the inside too. Only spacetime's curvature causes them to "exist" in the sense that they can be felt when bumped against.

            Imagin

      • There is no empty space anywhere in the universe. Look at the quantum foam. Also, it would violate Heisenberg's uncertainty principle.

        If a point was empty, all values would be evaluated to zero. ALL values. No can do.

    • by Luckyo ( 1726890 )

      Human perception is defined by time. We observe everything in relation to time, because time is so critical to us.

      This is not the same in context of quantum physics and this argument.

      • Time is a standalone concept via entropy. Entropy establishes the arrow of time. The bodies of work and equations have no variable named, "human."

    • by Cito ( 1725214 )

      While I'm asleep, I cease to exist

      • While I'm asleep, I cease to exist

        If you wish to cease to exist while you are sleeping... that can probably be arranged.

        • by Cito ( 1725214 )

          lol

          If I live alone, and I'm not conscious to observe myself do my particles delocalise annihilating me into a localized quantum cloud of electrons where time is irrelevant and when my soul observes my corporeal nonexistence it causes the localized quantum cloud to reconstitute my body whereupon I awake believing it was only a dream?

      • That might be a stretch indeed if the universe slept when you did.

      • When you die, do you cease to exist?

    • by idji ( 984038 )
      exactly, whoever wrote this piece of fluff didn't get Thompson, Rutherford and Bohr and all they worked through. How can he be a chem professor and forget Rutherford????
  • by 278MorkandMindy ( 922498 ) on Sunday August 27, 2023 @12:03AM (#63800552)

    Sure, they are not "empty". The other side is that they are "full"? The empty explanation is fine for general understanding. You can shoot particles through other particles with no interaction (sometimes) which means there is "empty" space in there.

    If you have a degree in the relevant topics, saying they are "empty" is not something you would say. The statement is fine for general understanding and seems a little nitpicky.

    How come x-rays go through this "not empty" space of some things, but not others? (Plus many other similar question)

    • by keltor ( 99721 ) *
      Both terms are equally not "true" in the real sense of atomic and even molecular interactions because they are terms that make sense from the macroscopic world. In the truest sense of the word, Barbatti is actually just as wrong as those who say atoms are empty. Because the terms simply do not apply at this level.
      • by Uldis Segliņš ( 4468089 ) on Sunday August 27, 2023 @01:47AM (#63800658)
        Exactly! And this includes the magical word observation. There is no one and strictly defined observation. There are different ways we can detect something. Unfortunately we can not see, touch, feel a nucleus or an electron. They are not showing like balls floating in a pool, lit by sunlight and visible with all their properties live at the moment and with 200kHz framerate and waiting for us to bend down and pick one out. The ways to detect something at that scale are extremely few and to make matters even worse, can be affected by other unintended, external effects. That's why we need extremely complex machines with kilometers diameter. Some ways of detection, or "observation" can detect a nucleus starting to be detectable from further away from it's center meaning it is big and soft, others pretty close implying it's like a small hard ball. So both are true and if you strictly explain only from one perspective, you are wrong - not explaining the full picture. But we sometimes don't have time or energy for fuller explanation.
        • This is a common misconception. You are conflating observation with measurement and anthropomorphizing both. Observations are not restricted to, nor defined by human eyeballs. Quantum physics works for the blind and has done so way before humans became sentient. Like, say 13.5 billion years ago.

      • There has to be an associated field. A field fills all of space, even if for practical purposes it can decay extremely rapidly. This is how Newton's spooky action at a distance through forces was banished from Physics.
        • What is the field associated with entanglement?

          • by HiThere ( 15173 )

            According to a recent paper it's probably polarization. You don't want to call that a field? Oh well.

            FWIW, I think the static picture of an isolated atom or particle is due to modeling the results of tests with an averaging filter. It *could* be static, but there's no reason to believe so. It just makes for a simpler model. (OTOH, I'm no expert in the field.)

          • Who knows? Maybe you'll be the one to discover an appropriate field formulation that doesn't contradict Bell's theorem, and then you'll get your Nobel prize when you're 70.
    • Wouldn't the explanation be that the x-ray photons are absorbed and re-emitted by the electron not empty space?
  • Empty and full aren't really meaningful when the best you can do is talk about wavefunctions and mumble about collapses and renormalizations.

    • If spin was really spin, would electrons rotate faster than light?

      • by ceoyoyo ( 59147 )

        Yes. You have to define what you mean by the radius of an electron, but if you imagine them as a blob or shell of charge of a size that's reasonably compatible with experiment, their "surface" would have to spin at (IIRC) something like 100x the speed of light to account for their intrinsic angular momentum.

    • Not so. Gravity worked far before Newton and Einstein weighed (a carefully crafted pun) in. Very few scientists felt the theories were mumbo humbo. Failure to fully comprehend by lay does not negate the body of work.

  • by Tablizer ( 95088 ) on Sunday August 27, 2023 @01:08AM (#63800622) Journal

    ...our everyday life human notions of things are not very useful. Things like "empty", "solid", "cloud", "dark", "moving", etc. don't translate very well to these scales.

    Arguing over such vocabulary is mostly pointless there. Even "time" has questionable usage there.

    • by lsllll ( 830002 )
      Kinda funny that not only don't these words translate well to these scales, but neither does Newtonian physics? Quantum physics is a completely different beast.
  • by sgunhouse ( 1050564 ) on Sunday August 27, 2023 @01:29AM (#63800640)
    You need to add a symbol indicating the superscript there, such as ^ or ** depending if you prefer calculator notation or C notation. 10^-12 or 10**-12
  • Quote from the article: "In atoms and molecules, electrons are everywhere! Look how the yellow cloud permeates the entire molecular volume in Figure 1. Thus, when we see that atoms and molecules are packed with electrons, the only reasonable conclusion is that they are filled with matter, not the opposite."

    Just because in the snapshot you see is a "yellow cloud", it doesn't mean that "the only reasonable conclusion is that they are filled with matter, not the opposite".

    I can show you snapshots of people whe

  • We don't have any clue whether atoms are "empty" or not. This is because our human-scale concepts do not adequately describe reality at the atomic and subatomic levels.

    We can only describe experiments' results as probabilities. That is, whenever we look atoms are as Sagan described: made of small concentrations of matter like the electrons and the nucleus. When we don't look and let particles evolve, well... by definition, we don't know. But we do know how the probabilities of outcomes of experiments evolve

    • by HiThere ( 15173 )

      FWIW, I think waves and particles are equally easy to explain, it's when what you see depends on how you look that things start getting difficult.

      • You make a point.

        what you see depends on how you look

        is totally wrong. Examining the various verified equations, experiments, and theories, we don't find any variables regarding "see" or "look." Humans have nothing to do with it.

  • Sure, electron orbitals are smeared across space in fanciful shapes like twisted balloon toys. No spinning, no vibration, no orbit. And yet these orbitals have angular momentum. How does that work? They may show relativistic effects from very high orbital velocities. What the heck is velocity for an orbital?

    • by ceoyoyo ( 59147 )

      Angular momentum is what happens when you rotate something that's not a scalar. Your experience of angular momentum is rotating lots of little vectors describing the spatial separation between some blobs of energy. The intrinsic angular momentum of a particle is the result of rotating the intrinsic vector (for bosons) or spinor (for fermions) of its field.

      Spin and intrinsic angular momentum arise pretty inevitably from the geometry of quantum mechanics. It's our misunderstanding of macroscopic angular momen

      • What seems weird to me is the idea that an electron shell could be rotating.

        • by ceoyoyo ( 59147 )

          They aren't. The orbital angular momentum is from the electrons that occupy those shells.

          Does it seem strange that the solar system has angular momentum?

  • The wave *function* collapses whenever there is interaction/interference of any kind. The bigger myth is that this is in anyway dependent on some human wanting to conduct a measurement. Even if nobody looks, that radioactive decay either happens or does not happen and in turn can cause other things to happen or not happen. The cat is either dead or not, even if we do not know whether it is dead or not.

    • Why do you think wikipedia says: "According to quantum theory, it is impossible to predict when a particular atom will decay, regardless of how long the atom has existed."?

    • The cat is either dead or not, even if we do not know whether it is dead or not.

      True. However, some think human knowledge is a factor in the paradox.

      Somewhere, in a forest, a squirrel has died. Of that, we can be sure, whether humans visit that forest or not.

  • by khchung ( 462899 ) on Sunday August 27, 2023 @05:41AM (#63800924) Journal

    This is just playing word games. Atoms aren't empty in the same sense that an occupied house isn't empty no matter how large the house is. Yes, the space is the atom "filled" with electrons in the sense that you cannot add another electron to it.

    But in another human common sense view, "being full" means that

      space occupied by the atom = size of its constituents

    Then the atom is indeed "empty" because the size of the nucleus and the size of the electrons is way way smaller than the size of an atom.

    At most, an atom isn't empty in the same sense that with one person living in a 1000 sq ft house (or even a "house" with the size of the Earth), the house "isn't empty". But that is a long way from the house "full".

    Trying to argue this from a scientific angle is just as futile as arguing whether the house above is "empty" or not.

  • by SendBot ( 29932 ) on Sunday August 27, 2023 @07:08AM (#63801012) Homepage Journal

    She wasn't Kitty Oppenheimer when the movie characters spoke that dialogue. She was married to Richard Harrison at the time and had his last name.

  • What is this, even?

    It sounds like seventh-grade physical science gone wrong.

    You're talking about multiple fields interacting at both energetic and information-horizon levels, quarks as properties, gluons accepting mass, mass canceling gravity in the Maxwell quaternions, and everthing hanging on a vacuum-structure n-dimentional discretized lattice. At least.

    "Uh, Bob, it's not empty you know."

  • by chas.williams ( 6256556 ) on Sunday August 27, 2023 @07:56AM (#63801084)
    Are you happy now? He's complaining about the Bohr model used to describe some of the simpler interactions because the quantum detail doesn't matter. This model is still used in computational chemistry, i.e. semiempirical Hamiltonians. Modeling elements as "heavy hydrogens" with only outer shell electrons is faster than full density functional theory. For a lot of calculations, you don't need DFT. Complaining about the models is silly. Use the right model for the right problem.
    • Correct. A parallel is the difference between Newton's laws of gravity and Einstein's relativity. If we plug low velocity and low gravitational energy into relativity, we get Newton!

  • by WaffleMonster ( 969671 ) on Sunday August 27, 2023 @08:19AM (#63801114)

    TFA keeps asserting there is massive amounts of empty space and then talks about "quantum clouds" as if they fill up all the space until something looks. It continuously derides useful high level approximations as if the people using them are not fully aware their convenience model does not represent the real thing with perfect fidelity.

    "However, interpreting the quantum cloud as probability does not mean it is just a measure of a lack of knowledge about the system. If I left my keys in one of my jacketâ(TM)s two pockets, but I am unsure which one, I may write a probability function with a 50 per cent value at each pocket and zero value at every other point of my office. This function obviously does not imply that my keys are delocalised over the two pockets. It just states my ignorance, which can be easily fixed by checking the jacket."

    "When we pile objects on top of each other, what keeps them separated is not their masses but the electric repulsion between the outmost electrons at their touching molecules. (The electrons cannot collapse under pressure due to the Heisenberg uncertainty and Pauli exclusion principles.) Therefore, the electronâ(TM)s electric charge ultimately fills the space."

    It all reads like gibberish to me. The only things people actually know about and are able to measure are outcomes of interactions. There are multiple known methods of deriving the exact same results as the schrodinger equation and an infinite number of equally valid interpretations of what any of it means. To draw conclusions about what is actually implied is presently outside the realm of science. You can guess and tell a conformant story you personally like but that's all your doing.

    A molecule is a static object without any internal motion. The quantum clouds of all nuclei and electrons remain absolutely still for a molecule with a well-defined energy. Time is irrelevant.

    Only in your mind when you define the problem away by ignoring unstable atoms.

    • Good ol Quantum religion, make shit up that works until tested, then make up more shit to fit the tests, until you have a model with so many edge cases it takes a thousand years of testing and millions of dollars to disprove.

    • by PPH ( 736903 )

      Yeah. The "dimensions" of an electronic depend on how hard you are pushing them together. The harder you push, the smaller they get. OTOH, that force can be felt over vast differences, so elections must be huge. At least on the order of the distance from a radio telescope to the Voyager spacecraft.

      The electrons cannot collapse under pressure due to the Heisenberg uncertainty and Pauli exclusion principles.

      These stand a better chance of defining the lower bound of an electron's size. Two electrons cannot occupy the same "quantum state". Which is spin and orbital in an atom. So, by definition, if an atoms orbitals ar

    • A molecule is a static object without any internal motion. The quantum clouds of all nuclei and electrons remain absolutely still for a molecule with a well-defined energy. Time is irrelevant.

      Only in your mind when you define the problem away by ignoring unstable atoms.

      An excellent point. When transformations occur at random according to a temporal probability density function arguing that time is irrelevant is clearly misguided. What he is really saying is that for my purposes (chemical properties of stable atoms) this is the model I like to use.

  • by Rambo Tribble ( 1273454 ) on Sunday August 27, 2023 @11:09AM (#63801338) Homepage
    ... is his thinking solid?
  • The quantum field of anything fills all of space. Of course in some places it is less than epsilon. So, just semantics.

    Meanwhile, molecules vibrate, so wrong on that, too.

    • by ceoyoyo ( 59147 )

      That was a pretty weird statement from a chemist. He seems to have gotten to the time-independent Schrodinger equation and not realized that the name implies there's also a time-dependent version.

  • Our civilization results in us being bathed in a fairly strong 60Hz field. By the article's definition of "not-empty" nothing in human experience near technology is empty so I guess we need a new word for describing things like "empty boxes". Ridiculous word parsing pedantry.
  • If you look at the expectation of the mass distribution of an atom, almost all of it is in a very tiny fraction of the volume near its center (nucleus). The ratio of expectation of the density of the nucleus to that of the electron cloud well away from the nucleus is on the order of 10**17, larger than the density of conventional matter to the density of an excellent laboratory vacuum. So the idea of the atom as "empty" is not a bad approximation if you are talking about mass density
  • I'm all for providing students more realistic explanatory models, and do generally have to go beyond textbook descriptions to make that happen.

    But the point of such a model is to connect it to their intuition. If you don't care about intuition then just give them the Schrodinger equation and call it a day.

    To the end of something a student could realistically sketch or imagine, a completely space-filling model is just ridiculous and would only serve to obscure important details about the real structural comp

  • However, my extremely limited understanding (or rather, intuition) of quantum physics is that all particles come down to a wave function, which is effectively a probability field and that the probabilities are never precisely zero i.e. that there is a non-zero possibility that a particle could be anywhere in the universe. Therefore, unless we are defining "empty" to mean that there is a zero probability of any particle (electron in this case) being present in a volume, then I would posit that what folks mea

  • is that the quantum field is unchanging, and the apparent motion or change of particles is a topographic feature like a ridgeline. And macroscopic time like we experience and observe is a higher-dimensional ridgeline. Not an expert myself, but that analogy made a lot of sense to me.
  • Schrodinger's Box is completely full of cat until you observe it, and then there's a solid cat in one corner.

  • by caveat ( 26803 ) on Sunday August 27, 2023 @07:56PM (#63802270)

    The Schrödinger equation [wikipedia.org], the heart of this entire argument, has two forms – the time-dependent, and the time-independent. The time-independent is much easier to solve, but is much more general...it's the one that results in the "empty space" concept. Then again, actually visualizing the time dependent one still involves a very small (2e10-10 cm) and very light (9.1093837e10-28 grams) electron appearing at one point in a given space, which reduces that space's mass to as near zero as makes no difference.

    Also it's been 25 years since I suffered through CHEM 404: Phys Chem II - Quantum Mechanics, and I'm drunk, so whatever.

Children begin by loving their parents. After a time they judge them. Rarely, if ever, do they forgive them. - Oscar Wilde

Working...