Ars Technica has a new series on quantum mechanics (no math)

Miguel Morales at Ars Technica is beginning a new introductory guide on quantum mechanics, one he promises won’t require any math. If you’ve watched some of us wrangle over the implications of QM and wondered just what the heck we were so worked up about, this looks like it will be a good series for coming up to speed.

This first entry focuses on the standard double slit and interferometer experiments. They’re clearly explained, so don’t let the jargon like “interferometer” throw you. This initial entry establishes the wave / particle duality, not just of light, but all quantum objects, including matter.

A cool line I’ll have to remember:

This is the fundamental mystery of quantum mechanics: particles move like waves and hit like particles.

The article also begins to show why the easy simple solutions that everyone initially reaches for when they first learn about this stuff, aren’t tenable:

But which path did the particle really take? The experiments show that the particles really take both paths. Despite much confusion (even among some physicists), this is the answer. But the question is based on a faulty mental image. The question assumes that a particle is really a little ball bearing, and thus must have chosen one path or the other. But this mental image is wrong. Particles really behave like waves when in motion. Asking which path a tsunami wave took when traveling between Hawaii and California really makes no sense—it is spread out. Similarly, asking which path the particle really takes makes no sense; it moves like a wave so it naturally takes all of the available paths.

Nor can we hope that this is just something that applies only to elemental particles:

Neutrons are also interesting because they are composite particles—a neutron is made up of three quarks. Even though it is made up of sub-particles, it still moves like a wave. Modern experiments have taken this much farther and regularly send Cesium atoms (more than 180 protons+neutrons+electrons), and even large molecules like Bucky Balls (60 atoms) and phthalocyanine with thousands constituent particles through similar interferometer setups. Even these huge composite particles move like waves and produce the telltale stripes in an interferometer.

Morales promises, in addition to not requiring any math, that he won’t get into the more philosophical aspects, so you don’t need to worry about being sold a particular interpretation. It looks like it will be a good opportunity to just learn the basics and begin forming your own opinions.

So far it’s pretty basic stuff, so if you’re already familiar with QM, it might not be worth your time. Although I’ve found going through these things, I almost always pick up new information.

31 thoughts on “Ars Technica has a new series on quantum mechanics (no math)

  1. “Asking which path a tsunami wave took when traveling between Hawaii and California really makes no sense—it is spread out. Similarly, asking which path the particle really takes makes no sense; it moves like a wave so it naturally takes all of the available paths.”

    Here we go again; relying upon analogies about the things we do understand to explain the true nature of reality, the very thing we do not understand. This is exactly the same slight of hand that Bernardo Kastrup uses to justify his M@L theory with all of its dissociative alters who are “individual whirlpools” in a large body of water.

    What really cool though, is now I know that my 150 grain slug exists as a particle when I load it into my 30-06, but when I pull the trigger and it leaves the barrel at high velocity is automagically changes into a wave until it collapse when the wave comes in contact with the deer I was aiming at. That is really, really cool…. Oh wait a second, that’s only true for particles as large as Bucky Balls. Yeah, that right. It’s just like life only begins with metabolizing compounds and likewise, consciousness only exists in certain animals with a line drawn at fish, amphibians, arthropods or somewhere else. I mean, we’ve got to drawn the line somewhere right, there isn’t any phenomenon in nature that could possibly be universal right? It’s just like Miguel Morales said, right?

    So much nonsense, and so little understanding…..

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    1. Just for grins: a 30-06 fires a 150-grain bullet (9.72 grams) with a MV around 2910 fps (887 m/s). That gives it a momentum of about p=8.62 kg⋅m/s. Wavelength is λ=h/p, so your bullet has a wavelength around 6.626e-34 ÷ 8.62 = 7.69e-33 meters.

      For reference, Planck Length is 1.6e-35 m. A proton has a charge radius of 8.4e-16 m, so your bullet’s wavelength is unimaginably smaller than a proton. Not really something you’re going to notice.

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    2. Very good Wyrd, but here’s an alternate grin to consider: The vacuum of space is an ocean of quanta, an ocean that has a quantum wave generated by a particle being fired through that ocean into a interferometer setup that “causes” the interference pattern. The science corroborates that this hypothesis is correct because a measurement detector set up on the slit where the particle is not passing destroys this quantum wave that is responsible for the interference pattern.

      The science and the subsequent mathematics that is used to support that science is only as good as the original assumption. Current science also confirms that the vacuum of space is an ocean of quanta causing the universe to expand, an ocean called dark matter and dark energy.

      It’s time to move past the superstitious dark ages of the Copenhagen interpretation and begin a new renaissance of science discovery.

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      1. “What’s your alternative description of the experimental results?”

        I thought you would be able to garner that answer from my previous post Mike. Anyway: there is no such thing as a wave function nor its infamous wave function collapse. A particle is a particle when it is loaded into the “gun”. It is a particle when that particle leaves the gun traveling through space at a high velocity, and it is a particle when it passes through the interferometer setup as it is a particle when it strikes the detector behind the slits. The ocean of quanta through which the particle is traveling at a high velocity is the source of the wave that causes the interference pattern as the particle passes through the interferometer setup.

        Empirically, we already know that the wave causing the interference pattern is quanta because the measuring device positioned at the other slit destroys the quanta wave that is responsible for the original interference pattern. I would think that sooner or later a theoretic physicist might make the same assumption that I did after reviewing the data knowing what we currently know about space consisting of dark matter and dark energy; but who knows. We are conditioned by our culture to conform to the status quo and to not think for ourselves; so it could be a while before someone other than myself rethinks the original Copenhagen assumption, or it could be never.

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        1. I actually was seeing the comments in notification order, not in the order listed.

          Your description resembles the pilot-wave interpretation, although it doesn’t reference dark matter and dark energy. I think you’re assuming more about those things than science currently knows.

          But pilot-wave has a particle and a wave the entire time. The wave guides or pilots the particle. David Bohm worked out the details in the early 50s. It’s deterministic and is probably the interpretation closest to “common sense”.

          However, it requires adding to the mathematical formalism. It’s also explicitly non-local, albeit in a way that doesn’t violate relativity. But while it doesn’t violate relativity, no one has yet succeeded in actually reconciling it with special relativity and classic field theory, which was done decades ago with the standard formalism. So most physicists aren’t hopeful that this is the answer.

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          1. “I think you’re assuming more about those things than science currently knows.”

            WOW!!! I’m not assuming one iota more about the vacuum of space than what science currently knows. Wyrd commented: “I call. Let’s see your hand.” Here are the facts Mike, and this is hand Wyrd:

            Fact number one (1): If dark matter and dark energy make up the vacuum of space, then that vacuum of space is an ocean of quanta.

            Fact number two (2): If the vacuum of space is an ocean of quanta, then that variable has to be taken into consideration when trying to resolve Richard Feynman’s “the only mystery in quantum mechanics” scenario, the infamous double-slit experiment.

            Seriously Mike, I just don’t understand your reluctance to entertain new concepts and/or alternate explanations for well documented experiments such as the double-slit. Are you so invested in the ascendency of authority figures that you honestly believe only those individuals are capable of coming up with new and novel ideas?

            Anyway kids, I’m done with this type of nonsense for now…..

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          2. Your cards seem to be all Jokers…

            “Fact number one (1): If dark matter and dark energy make up the vacuum of space, then that vacuum of space is an ocean of quanta.”

            I’ve never heard anyone suggest dark matter or dark energy “make up the vacuum of space” (whatever that’s supposed to mean). And what is an “ocean of quanta”? What properties does it have?

            “Fact number two (2): If the vacuum of space is an ocean of quanta, then that variable has to be taken into consideration…”

            In what way? How is either dark energy or dark matter supposed to have an effect on the two-slit experiment? DM and DE are completely different from each other and both are unknowns created as place-markers for observed cosmological mysteries. We don’t even know if DM is a particle or just how gravity works in that regime. Neither have any observed, known, or theoretical, effect on our tiny island rock in our small island galaxy.

            Given the two-slit phenomenon is very precisely described by the math and experiment, how would DM or DE fit into that picture? How do you think they change anything?

            “Are you so invested in the ascendency of authority figures that you honestly believe only those individuals are capable of coming up with new and novel ideas?”

            No, I’m invested in observational data, experimental evidence, and theoretical analysis. Also in education and experience. Worrying about “authority figures” is for crackpots. 😉

            Liked by 1 person

          3. Well played…… But on a dimmer note; I don’t think you grasp the concept of “burden of proof” Wyrd, because if you did, you wouldn’t be so obnoxious. You’re a smart guy, smart enough to ask pertinent questions; but if you do not possess the capacity to think outside the box of conventional wisdom for yourself and on your own terms, and have to rely upon me or any of the so-called experts to answer the questions you raised, there is nothing I can do to help. The ability to think for oneself is a gift, one either has it or they don’t. If I recall correctly, Philosopher Eric once referred to me affectionately or otherwise as a savant god. Maybe so……

            I’ll tell you what; why don’t you work some of your mathematical wizardry on Bucky Balls. I’d be quite interested to know what the Bucky Ball’s wave length would actually be when it automagically transforms itself into a wave once it is fired from the Bucky Ball cannon.

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          4. My questions were rhetorical; I never expected answers. DM and DE have something to do with the two-slit phenomenon? There is no answer possible to that. It is, as the saying goes, “not even wrong.” To be in the ballpark you have to at least be in the same city.

            Bucky Balls. Calculating the de Broglie wavelength is simple math, not wizardry. The formula is just: λ = h/mv. All we need is mass (in kilograms) and velocity (in meters/second).

            Here’s an experiment from 1999:

            The Vienna team sent a collimated beam of carbon-60 molecules through a slit made of silicon nitride […]. The slits in the diffraction grating were 50 nanometres wide and the grating had a period of 100 nanometres. […] The molecules had a most probable velocity of 220 metres per second, which corresponds to a de Broglie wavelength of 2.5 picometres (2.5×10^-12 metres) – some 400 times smaller than the diameter of the molecules.

            So really, really tiny. Even in such a small object, many times smaller than the object.

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  2. All learning is good!

    His opening three points, I quite agree with #2 and #3. I’m taking the same approach these days; focusing on what we can know and test. There’s more than enough there for me to deal with.

    Point #1 is fine, and may well be a determining factor for many, but the truth is that being fluent in Japanese can’t help but take your understanding of Japanese art to a different level. Learning the language is climbing a hill that gives one a very different view!

    Liked by 1 person

    1. I think that’s a good point. And it’s probably true that actually creating Japanese art, without a deep appreciation of Japanese culture, possibly including its language, isn’t feasible. Similarly, I think anyone who wants to do quantum mechanics, particularly come up with their own theories, has to be deeply emmeshed in the mathematics. I know I’ve only skimmed the mathematics, but even that much gave me insights I probably couldn’t get from just reading descriptions.

      But for people who want to just have a surface appreciation of it, hearing the math isn’t mandatory probably makes them much more likely to read the series.

      Liked by 1 person

  3. “When we read, another person thinks for us: we merely repeat his mental process. In learning to write, the pupil goes over with his pen what the teacher has outlined in pencil: so in reading; the greater part of the work of thought is already done for us. This is why it relieves us to take up a book after being occupied with our own thoughts. And in reading, the mind is, in fact, only the playground of another’s thoughts. So it comes about that if anyone spends almost the whole day in reading, and by way of relaxation devotes the intervals to some thoughtless pastime, he gradually loses the capacity for thinking; just as the man who always rides, at last forgets how to walk. This is the case with many learned persons: they have read themselves stupid.”

    Arthur Schopenhauer

    Liked by 2 people

    1. I don’t know the context of that quote, but presented alone, it seems to imply we shouldn’t read. That doesn’t seem like a good strategy for understanding things. It’s not like most of us have other ways of taking in information that is intellectually stimulating. Of course, figuring out what to read, that is the difficult part. Much of what’s out there is worse than useless. But being well read helps in separating the wheat from the chaff.

      Liked by 1 person

      1. “…it seems to imply we shouldn’t read.”

        That’s a very shallow assessment if that is the only thing you got out of the quote Mike. In order to understand Schopenhauer, one has to see him in his own historical context and as he saw himself.

        Schopenhauer considered himself to be a mystic of sorts. So what that means is that he was the originator of his own thoughts, and he relied upon no one other than himself for those thoughts and furthermore, he owned any and all conclusions derived from his intellectual synthesis. In short, Schopenhauer was an anti-establishmentarian. You won’t find many individuals like Schopenhauer today, especially in positions of leadership. His species has been effectively suppressed by our prevailing paradigm of conformance and compliance.

        If you haven’t seen it already, PBS has a short series titled “Hacking Your Mind”. The series offers some very interesting insights into human behavior. It’s well worth the time, relevant for the prevailing mob mentality we’re experiencing in America and I highly recommend it.

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    1. It’ll be interesting to see where he takes the series. It’s hard to avoid at least some mathematical notation with QM, but a lot of authors do a good job disguising it by only showing part of the notation and replacing the variables with pictures. I just hope he doesn’t try to explain entanglement with one of those awful analogies. Sometimes it’s just easier to admit we’re talking about particle spins.

      Liked by 1 person

  4. Ok, I’m interested. I’ve tried to make those points a couple of times.
    “particles move like waves and hit like particles.” Whatever they are, they interact in one place, like a particle, and where that place might be is best described by the mathematics of waves.

    *
    [gonna go watch now]

    Liked by 2 people

    1. It’s not bad reading, or at least I didn’t find it to be. Someone did complain to me about why they had to read about the experiments. Couldn’t the guy just explain things without that? That was my reaction years ago when I first tried to read about QM. But understanding the experiments is crucial, otherwise the bonkers stuff that follows just won’t be believable.

      Liked by 1 person

  5. I remember an old joke. “What is an integral?” “I don’t know. At first I didn’t understand, I didn’t understand, and then I got used to it.”

    This applies not only to integrals. There are many levels of understanding of complex things, for example, in physics. We can talk about the understanding of quantum mechanics at the level of a third-grader, tenth-grader, a novice physicist who does not use the theory of quantum mechanics or uses this theory as an applied thing, and, finally, a physicist working on the development of fundamental things in quantum mechanics.

    I think that help in understanding at every level is to be welcomed.

    Liked by 1 person

    1. Too true. No matter how much we know, it only takes us to a new frontier of ignorance. One thing I wish grade school science instruction admitted more often to students is how freaky weird a lot of this is and that no one knows why it is so.

      I still remember as a kid when I first found out about wave / particle duality. It was presented as the “solution” to the historical debate between the wave theorists and particle theorists, with no hint about how mysterious or controversial this “solution” actually is. I was left wondering what about it I just wasn’t getting.

      I have similar gripes about math instruction.

      https://www.smbc-comics.com/comic/how-math-works

      Liked by 2 people

  6. Forgive my ignorance, should not the diffraction grating graphic at the header of this webpage be offset 90 degrees perpendicular to the double-slit lines instead of parallel to slits? I think I have Schrödinger on my side here.

    Liked by 1 person

    1. Hmmm. The Ars Technica article does discuss the pattern being perpendicular to the lengths of the slits, but that was in reference to the interference pattern, that is, the pattern of bright bands with dark bands in between. His slits were pretty small, so the resulting pattern was narrow.

      In the graphic header (which comes from Wikipedia), we do have the pattern perpendicular to the length of the slits. It’s just that the slits themselves are wider, so the pattern is also wide. But the pattern itself is still perpendicular to the slits.

      Unless of course I’m the one confused. Always a possibility.

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