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How Many Elementary Particles Are There, Really?
- warumdarum 4mo agoSome powerof two many actual states + a fractal deterministic random generator for particle Explorers?
- EwanG 4mo agoAs 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 4mo agoIsn'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).
- BobbyTables2 4mo agoNot 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?
- colejohnson66 4mo agoThat'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 4mo agoHow 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.
- krapp 4mo agoI'll be sure to inform all of the physicists that @Noaidi on Hacker News has solved physics and that they can go home.
- GroksBarnacles 4mo agoDo you have a meaningful quantitative explanation with some math we can start building tech on, or will that require some... experiments?
- rolph 4mo agoplanck scale is the theoretical limit to disassembly.
- 4mo ago
- jerf 4mo agoYou 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.
- Noaidi 4mo ago> They're manifestations of fields. Or wave. Everything is a quantum wave. https://www.vlatkovedral.com/everything-in-the-universe-is-a-quantum-wave/ https://www.vlatkovedral.com/everything-in-the-universe-is-a...
- GroksBarnacles 4mo agoA 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 4mo agoYes, 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.
- dpark 4mo ago> I am no mathematician, but the math needs to start with that fundamental principle. This is a weird sort of hubris. “I’m not qualified to do this job but I can certainly tell you how it needs to be done.” > And if everything is a wave there are no discrete quantities beyond our definition of what constitutes the end, or borders, of the wave. This is not true in multiple ways. First, it’s known that these particles exhibit quantum behavior. This is measured and confirmed over and over. Many measures are in fact quantized. Second, existing as a wave does not mean no discrete quantities. Even in everyday materials we observe situations like standing waves that are effectively quantized. https://en.wikipedia.org/wiki/Standing_wave https://en.wikipedia.org/wiki/Standing_wave
- jiug 4mo agoEven 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.
- jiug 4mo agoEven 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".
- antonvs 4mo 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.
- RobotToaster 4mo agoUnified field theory https://en.wikipedia.org/wiki/Unified_field_theory https://en.wikipedia.org/wiki/Unified_field_theory
- slashdave 4mo ago> I have to wonder if all these particles are somehow manifestations of a simpler thing Yes, theorists have been working on a similar idea for decades. > the “wave photon” and the “particle photon” seemed like possibly different things? No. Wave vs particle is just a different description of the same thing.
- deleted 4mo ago[deleted]
- aqula 4mo agoYou might be interested to look up the Williamson-Van der Mark model. It says that an electron is just light that loops in on itself and shows how properties like mass, charge and spin can emerge from such a geometry. It's fascinating because it opens up the question whether every particle could be described in terms of different ways light can loop in on itself.
- Noaidi 4mo agoThere 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 https://www.mdpi.com/2624-960X/5/2/31
- deleted 4mo ago[deleted]
- d4ng 4mo agoThere are also 17 wallpaper groups. That always seemed like a funny number. I know it's a long shot, but is there a relation?
- slashdave 4mo agoFunny to who? The decimal system, for example, is a human invention.
- d4ng 4mo agoIt's a reasonably sized prime number regardless of base.
- sva_ 4mo ago> reasonably sized prime number I feel like you're alluding to something but won't say to what? Maybe something like the 'fine-tuned universe' hypothesis?
- d4ng 4mo agoActually I’m not alluding to anything specific. I just wondered whether the 17ness of wallpaper groups and fundamental particles was some sort of mapping from a related common object. Obviously a long shot as previously mentioned.
- gus_massa 4mo agoAs the article explains, counting is very hard. IMHO, I like to count the x3 colors of quarks and the x2 chirality of bosons. So I get 16*3 fermions and 1+8?+3?+1 bosons, in total 61 but the number of bosons is not a hill I will do die on. On the other extreme, there are some proposal to reduce the number of particles, in particular it makes a lot of sense to consider the electron and neutrino as a single class of particle, and the up and down quark as a single class of particle, so I guess the number goes down to 6 fermions + 4 bosons = 10? in total (I'd keep chirality, so perhaps 12+4=16?). And there are even more extreme proposals to consider quarks and leptons in a single bag of mud. In particular this was popular like twenty years ago, but the experiments disagree (IIRC by a small amount, IIRC it's not a very bad approximation) https://en.wikipedia.org/wiki/Georgi%E2%80%93Glashow_model https://en.wikipedia.org/wiki/Georgi%E2%80%93Glashow_model I tried to count the particles there and I gave up, let's say a lot. And you still have to add gravitons (and their weird cousin particles) and perhaps more than one Higgs bosons. So the number should increase in the future. And there are still ideas to add a global x2, because it would be nice if every bososn has an undiscovered fermion companion and vice versa. IIRC it's falling out of fashion because the simple versions don't agree with the experiments https://en.wikipedia.org/wiki/Supersymmetry https://en.wikipedia.org/wiki/Supersymmetry but it sounds interesting :( --- In conclusion: Don't get too attached to the number 17.
- tlogan 4mo agoD
- eximius 4mo agoHmm if a particle is a quantized packet of a field, then if multiple quantizations are possible in a field, then it's possible for more particles than fields?
- tlogan 4mo agoI somehow deleted my original comment. I actually made mistake. There are 16 fields: * 12 matter fields (6 quarks + 6 leptons) * 1 gluon field (an 8-component SU(3) field) * 1 weak field (a 3-component SU(2) field) * 1 hypercharge field (a 1-component U(1) field) * 1 Higgs field (SU(2) x U(1)) We have 17 particles is because W+, W-, Z are combination on 2 fields. I think counting particles is just going to confuse people because they are really not “balls”.
- nok22kon 4mo agoit's called quantum occupation number - literally how many particles (packets) are at a particular point in space-time. only for boson fields. think like the intensity of a RGB pixel - R can be 1, or maybe 10 for a particular pixel, thus you have 10 red "packets"
- unholiness 4mo agoStopped reading after "Yet in the mathematical equations that define the Standard Model, the eight gluons are distinct from one another in the same way that the W and Z bosons differ." W and Z bosons, photons, etc have fixed masses, charges, interaction strengths with other particles. These properties can exactly be listed and looked up in a table of elementary particles with discrete rows. Gluon color is continuous property in a vector space. Gluons can have any color in that space, with any combination of the 8 basis vectors (and that choice of basis is also completely arbitrary). The color |g1> is no more valid than the color (|g1> + |g2> + |g8> / √3) or any other of infinite combinations. Calling this "8 gluons" is like saying there's "3 photons" because they can have momentum in 3 dimensions. If you want to argue there's infinite kinds of gluons, go ahead, but there aren't 8.
- LearnYouALisp 4mo agoHuh, I didn't even know we had sub-species ID of gluons now
- slashdave 4mo agoAnd the different charge W bosons are just the same particle, via time reversal symmetry.
- pdonis 4mo ago> W and Z bosons, photons, etc have fixed masses, charges, interaction strengths with other particles. But you can form a continuous set of linear combinations of these things, just as you can with gluons. Indeed, what the article calls W and Z bosons (and photons) are just such linear combinations--the ones that appear in the low energy limit after the electroweak phase transition occurs. Before that phase transition, different linear combinations (i.e., a different basis of the electroweak vector space) are the ones that naturally appear. So saying that there are two W, one Z, and one photon is really counting basis vectors in the electroweak vector space, just as saying there are 8 gluons is really counting basis vectors in the gluon sector of the strong interaction vector space.
- unholiness 4mo ago
- calimoro78 4mo agoThe answer is 42.
- sscaryterry 4mo agoNow that would be wildly co-incidental and creepy :)
- Alulim 4mo agoI'm not a physicist (so take this with a grain of salt) but I have spent a lot of time trying to find an answer to this question. If you interpret the physics before Spontaneous Symmetry Breaking as more fundamental, and you treat the antimatter fields as distinct, then I think you can reasonably claim that there are 30 fundamental fermion fields. Specifically, in each of the 3 generations, you have: 1. The left-handed lepton doublet field, and the antimatter equivalent. 2. The left-handed quark doublet field, and the antimatter equivalent. 3. The right-handed electron singlet field, and the antimatter equivalent. 4. The right-handed up-quark singlet field, and the antimatter equivalent. 5. The right-handed down-quark singlet field, and the antimatter equivalent. The bosons are more confusing to me, but I think a reasonable person might say that there are 16 fundamental boson fields: 1. The four scalar boson fields. 2. The eight gluon fields. 3. The three W boson fields. 4. The B boson field. The B boson couples to every fermion (via hypercharge), while gluons only couple to quarks (via color) and W bosons only couple to the doublets (via weak isospin).
- nok22kon 4mo agothat's pretty impressive for a non-physicist (assuming no LLM)
- mac3n 4mo agogoing in the opposite direction, as few as two https://en.wikipedia.org/wiki/Preon https://en.wikipedia.org/wiki/Preon
- ziofill 4mo agoPhysicist here. I don’t buy some of these distinctions, like the chirality. Chirality is an observable, it’s like saying there are two photons because they can come in two polarizations, but polarization is not an inherent property: it depends on how we measure it. So I could describe any photon in the left/right chiral basis just as well as in the vertical/horizontal basis or any two antipodal points in the Poincaré sphere, so which is the “right one”? Neither. Spin on the other hand (which is where polarization comes from) is well-defined for any photon and it’s always 1 (the astute reader will wonder why the projection of spin 1 does not take 3 eigenvalues 1,0,-1 and it’s because photons are massless so the 0 projection never occurs because there is no rest frame for massless particles).
- gus_massa 4mo agoChirality is a real property of (most) elementary particles. For example the electron with left chirality has a weak hypercharge of -1, but the electron with right chirality has a weak hypercharge of 0. https://en.wikipedia.org/wiki/Weak_hypercharge#Definition https://en.wikipedia.org/wiki/Weak_hypercharge#Definition In some sense, they are very different particles. Also, only the left version interact with the weak interaction.
- ziofill 4mo agoAh, then I was thinking about helicity
- gus_massa 4mo agoI expected the article to explain "helicity" and then say "and chirality is almost the same (for fast particles)", that is good enough for not specialist. There are a few graphics here and there that show helicity, but that paragraph in the text is totally unintelligible and the only conclusion is that there is something with right and left.
- nok22kon 4mo agochirality is how particles get mass - the Higgs field gives fermions mass by coupling their left and right-chiral parts, causing chirality mixing
- Sniffnoy 4mo agoI feel like you ought to be go lower than 17, down to 9, by not counting the 3 generations of fermions as distinct (so you've just got up-type quark, down-type quark, electron-type particle, and neutrino). After all, if they can mix with one another, should they really be considered entirely different particles?
- ndsipa_pomu 4mo agoThere's different behaviour between the 3 generations though as a muon will decay whereas an electron won't.
- aeonik 4mo agoWe don't know that electrons don't decay for sure. If we live in a false vacuum, for example, that could allow them to decay.
- ndsipa_pomu 4mo ago> We don't know that electrons don't decay for sure. However, we don't expect electrons to decay as we don't know what they would decay into i.e. there doesn't seem to be anything plausible with a lower energy configuration. > If we live in a false vacuum, for example, that could allow them to decay. Possibly, but that's quite speculative and if our vacuum does decay, then there's a good chance we wouldn't be around to see the differences.
- ckdot 4mo ago1
- OutOfHere 4mo agoIn string theory, there are open strings and closed strings, so that's two. (It's just a theory.)
- Razengan 4mo agoAre there ANY, at all?
- anthk 4mo agoI wish the Torstone particle from Pinĉak was validated.
- brap 4mo agoI sometimes wonder if at some point we’ll discover that the fundamental laws of the universe are simply far beyond anything we can even remotely comprehend, like explaining a microprocessor to bacteria. But then what if we end up with ASI that can comprehend and make it useful for us?
- lacoolj 4mo agoI think it's less "how many are there" and more "how small can we go before the influence is too negligible to matter, or is too small to be affected by anything we could physically do or observe" I mean, there is definitely no "floor", nor "ceiling". Size infinitely gets smaller and infinitely gets larger. We are probably sitting on top of what super-gigantic humans of astronomic proportions would consider a lepton.
- NoMoreNicksLeft 4mo agoOne. The question is, does this refer to types or count?
- playorizaya 4mo ago[flagged]
- lompad 4mo agoYou really don't seem to understand what a model is. A model is essentially an approximation of reality capable of making predictions. If those predictions get confirmed, the model will be accepted. Barely anybody with reasonable education in physics would confuse a model built for humans to understand reality with actual reality. Models are not reality, they are a tool used to describe it, nothing more and nothing less. Let's take Newton's laws as an example. Obviously, there is not a literal force vector manifesting and pushing objects. But it's a good predictor of behavior and allows building of understanding. The Higgs Particle did exactly what it was expected to do and works just like Higgs predicted. If you look at click-focused press and think their bad explanations properly describe the state of physics, you're simply mistaken. However, to understand that, you have to actually learn. And, if you intend to revolutionize physics, you also need to be able to make better predictions. Which is ... unlikely, to say the least. Again: Models in physics approximate reality. They do not actually exactly describe fundamental reality, only how it works within the limits of the model.
- playorizaya 4mo agoNobody said that gravity is a literal force vector pushing objects, and if you did (a la aether) the theory would be discarded, just like the Standard Model will be discarded when people realize the universe is not made of balls. Everybody knows what is meant by "model" and "theory" - there is no need to be so condescending for no reason. The Standard Model asserts that the world is made of some number of basic "building blocks" and yet has had considerable trouble proving it thus far. Insofar that it is a model of real, non-fictional physics, and not a thought experiment but an actual attempt at describing the universe in terms of its parts - it's obviously incorrect. And Higgs DID NOT live up to providing an explanation of where mass comes from. That was the whole point, it was "the god particle" because it was supposed to complete the Standard Model by providing a mechanism for mass. It didn't do that. We still don't know.
- duncangh 4mo agoThis and not being able to divide by 0 in math always drove me up the wall in school. Encountering a god level difficulty unsolved problem in the first 5 minutes of discussion around the basics of the field and then shrugging and continuing to build castles of complexity atop the seemingly rickety foundation irrationally irked me. Feels good to get that off my Chest. I’ve been holding it in for ~20 years
- butlike 4mo agoOK this one still trips me up. Why isn't 5/0 5? If I have 5 apples, and I divide that group by 0, I STILL HAVE 5 APPLES. If I have 5 apples, and I divide that group by 2, I have 2 groups of 2.5 apples.
- t0mpr1c3 4mo agoBecause 0 is not 1. Consider the equation x = 5/y. Let us assume that the variable x is defined for every value of y. Then x * y = 5 (after multiplying both sides by y). Let us also assume, as you suggest, that when y = 0, x = 5/0 = 5. Then x = 5 = x * y. The only solution to this equation is y = 1, a contradiction.
- niklasbuschmann 4mo agoAt least for the fermions the answer is a nice power of two for each generation. There is the electron, the neutrino, the red, green and blue up quark and the red, green and blue down quark, giving 8 fermions per generation. Since one can distinguish between particles and antiparticles, one could also argue for 16 fermions per generation. Also one can distinguish between left and right handed particles, giving a total of 32 fermions per generation.
- VonTum 4mo agoWhat is a "half degree of freedom" in the matter field? (5.5 DOF from the article) Does anyone here know?The article glossed over it very quickly