How Many Elementary Particles Are There, Really?

(quantamagazine.org)

47 points | by rwmj 3 hours ago

7 comments

  • tlogan 2 minutes ago
    I think we have 17 elementary particles (not 61 or whatever), because we have 17 fundamental fields (that we know about).

    We say “elementary particles,” but physicists are really talking about fundamental fields. I am not a physicist, so I can be wrong.

  • BobbyTables2 1 hour ago
    Not being a Physicist, I have to wonder if all these particles are somehow manifestations of a simpler thing.

    Might there have been a point in time (long ago) where the “wave photon” and the “particle photon” seemed like possibly different things?

    • jerf 1 hour ago
      You don't have to wonder, because they are. They're manifestations of fields.

      I think it is a reasonable answer to tell people "if you're looking for the short list of simplest things, the number of types of fields there are is probably what you're looking for".

      That doesn't invalidate this question in general, though the number of different answers from people looking at the same thing suggests it may be underspecified.

      • HarHarVeryFunny 20 minutes ago
        But of course one can then question why are there exactly N different types of fields, with their specific types of interaction (at least in our universe)? Why should we suppose that this is the most fundamental description of reality, rather than being emergent from something else?
        • tsimionescu 5 minutes ago
          Well, why would there be fewer than N? There is no general principle that we can impose on the world, it just is, we can only discover what the laws and components of the world are (hopefully). I'm not claiming it's impossible for there to be fewer fields than we think right now. But there is no reason to believe there should be.
      • rwmj 51 minutes ago
        To me that raises the opposite question, why are there so few fields? (Compared to what I'd imagine, infinite)

        [Edit: I suppose I'm imagining waves or frequencies of waves, rather than fields, hence why in my imagination there would be an infinite variety]

        • Filligree 45 minutes ago
          Not all fields interact with all other fields. You can think of them as a loosely coupled graph…

          There might be any number of graph components with no connectivity to our fields at all, and we’d never know. Assuming, of course, that we’re including gravity in this logic.

          There’s also might be any number of arbitrarily complex components which are only connected through gravity. That’s a decent candidate for what the dark sector actually is.

      • TheOtherHobbes 38 minutes ago
        In QFT every particle type has its own field.
        • antonvs 27 minutes ago
          Every particle type has its own field, but the OP article is counting a single particle type multiple times based on properties like spin and polarization. At one point the article reaches the number 118. That corresponds directly to 37 quantum fields once you take the "double counting" into account.
      • antonvs 29 minutes ago
        > if you're looking for the short list of simplest things, the number of types of fields there are is probably what you're looking for

        Definitely. It's rather strange that the OP article doesn't even mention the word "field". It seems that people in general have a hard time letting go of the idea of particles as fundamental.

        A good overview of this is "There are no particles, there are only fields" (https://arxiv.org/abs/1204.4616) by physics prof Art Hobson.

        Fields collapse the zoo described in the article significantly, because particles and antiparticles arise from the same field, and similarly, spin, polarization, and helicity are properties of the same field. Taking this into account, the 118 particles number that the article reaches at one point drops to 37 fields.

      • Noaidi 59 minutes ago
        > They're manifestations of fields.

        Or wave. Everything is a quantum wave.

        https://www.vlatkovedral.com/everything-in-the-universe-is-a...

        • GroksBarnacles 45 minutes ago
          A wave is already what we call a manifestation of a field, maybe I skimmed too quickly but I don't get the author's breakthrough point.
          • Noaidi 21 minutes ago
            Yes, the field is the substrate.

            "I insist upon the view that 'all is waves'."

                Letter to John Lighton Synge (9 November 1959), as quoted by Walter Moore in Schrödinger: Life and Thought (1989) ISBN 0521437679 
            
            It is not a breakthrough, it is just something we refuse to see, something that was known for a century.

            "All is a wave" is the unifying principle. I am no mathematician, but the math needs to start with that fundamental principle.

            The very notion of calling it "qunatum" physics is probably wrong since quantum is "a discrete quantity of energy proportional in magnitude to the frequency of the radiation it represents."

            And if everything is a wave there are no discrete quantities beyond our definition of what constitutes the end, or borders, of the wave.

        • andrewflnr 12 minutes ago
          > Now, when I told my editor at Allen Lane about my own interpretation, he immediately said “It’s Many Worlds on steroids!” There is a grain of truth in that, ...

          Dude, this is an answer to an entirely different question. He's proposing an interpretation of QM, which is independent from "how many fundamental particles".

        • antonvs 24 minutes ago
          A wave is a phenomenon that propagates through a field - i.e. the field is what allows the wave to exist.

          (The philosophy of that admittedly gets messy, though, e.g. "are fields real objects?")

    • jiug 23 minutes ago
      Even if we use "wave photon" and "particle photon" alternatively, they are only convenient ways of talking about the behavior of the "photon field". The same way when we say "it is raining" we don't mean there is an "it" that "rains" we should try to avoid giving too much litteral meaning to these descriptions.

      That said, I get it is difficult, especially because we are using everyday language to talk about very-much-not-everyday stuff. We all needental hooks to anchor new knowledge and most of our intuition comes from the classical (not-quantum) world around us.

      As a physicist, I feel the art is in learning when to use what description, what Sean Carrol calls "poetic naturalism".

    • RobotToaster 10 minutes ago
    • colejohnson66 1 hour ago
      That's what the various string theory proponents start from. There's "too many" different subatomic particles, so there surely must be something smaller that they're composed of?
      • Noaidi 56 minutes ago
        How long can you break something apart until you cannot any longer? The things we are breaking apart are illusions in a sense. There will always be a smaller particle because that is what we are looking for.

        When we understand that everything that we see is a manifestation of a probability wave, then we will understand everything is a wave and end these foolish experiments.

        • GroksBarnacles 43 minutes ago
          Do you have a meaningful quantitative explanation with some math we can start building tech on, or will that require some... experiments?
        • krapp 54 minutes ago
          I'll be sure to inform all of the physicists that @Noaidi on Hacker News has solved physics and that they can go home.
    • jiug 40 minutes ago
      Even though "particle photon" and "wave photon" are used alternatively, they are just convenient ways of talking about the behavior of the same "photon field". The same way when we say "it is raining" we don't mean that there is a "it" that "rains", we should try avoid taking these descriptions too literally.

      That being said, is difficult because we are using language to describe very-much-not-everyday stuff. We all need mental hooks to anchor new knowledge and most of our intuition is based on the classical (not-quantum) world aroud us.

    • antonvs 22 minutes ago
      > I have to wonder if all these particles are somehow manifestations of a simpler thing.

      Someone else already mentioned that yes, they're manifestations of quantum fields. This is well established - the dominant theory of particle physics, the Standard Model, is a theory of quantum fields.

      In that context, a particle is simply the smallest excitation of a quantum field that can be detected. Fields can be "excited" (fluctuate) in many different ways, and the OP article is interpreting each one of those as a different type of particle. It's misleading.

  • d4ng 7 minutes ago
    There are also 17 wallpaper groups. That always seemed like a funny number. I know it's a long shot, but is there a relation?
  • EwanG 1 hour ago
    As usual, the hard problem is how you define "Elementary" which is why the posters always show 17, and then you get numbers that go as high as 995.5 (and the .5 is an interesting result as well).
    • rwmj 37 minutes ago
      Isn't it just a thing that cannot be broken into / explained as a combination of more elementary things? ie. as far as we know an electron is an elementary particle because it can't be split into smaller components nor is there any evidence that it contains something smaller (unlike, say, an atom or a proton).
  • warumdarum 1 hour ago
    Some powerof two many actual states + a fractal deterministic random generator for particle Explorers?
  • Noaidi 1 hour ago
    There are no particles. Everything is a wave.

    The Everything-Is-a-Quantum-Wave Interpretation of Quantum Physics

    https://www.mdpi.com/2624-960X/5/2/31