# Incomplete Standard Model? **URL:** \ **Category:** Factual Questions\ **Created:** [March 18, 2019, 1:23am UTC](https://boards.straightdope.com/t/incomplete-standard-model/831285 "2019-03-18T01:23:03Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Enola\_Straight](https://avatars.discourse-cdn.com/v4/letter/e/dec6dc/32.png) [@Enola\_Straight](https://boards.straightdope.com/u/Enola_Straight)\ **Post date:** [March 18, 2019, 1:23am UTC](https://boards.straightdope.com/t/incomplete-standard-model/831285/1 "2019-03-18T01:23:03Z")
behold: > **[Standard Model](https://en.wikipedia.org/wiki/Standard_Model#/media/File:Standard_Model_of_Elementary_Particles.svg)** > > The Standard Model of particle physics is the theory describing three of the four known fundamental forces (electromagnetic, weak and strong interactions — excluding gravity) in the universe and classifying all known elementary particles. It was developed in stages throughout the latter half of the 20th century, through the work of many scientists worldwide, with the current formulation being finalized in the mid-1970s upon experimental confirmation of the existence of quarks. Since then, proo Are there three undiscovered scalar bosons? ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [March 18, 2019, 3:02am UTC](https://boards.straightdope.com/t/incomplete-standard-model/831285/2 "2019-03-18T03:02:32Z")
C’mon guys, get with it. I want to tell him to check his sock drawer but I can’t until there’s a serious answer. How about a serious question? Are you asking whether the spaces beneath the Higgs Boson need to be filled in? I think that’s just an artifact of how they decided to arrange the graphic. The six quarks all get paired with the gluon, e.g. because they carry the strong force. The four gauge bosons represent only three forces, because the W and Z bosons both are carriers of the weak force. That’s not obvious when compacted this way. So while there might be more scalar bosons, the chart says nothing about their lack. ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [March 18, 2019, 3:10am UTC](https://boards.straightdope.com/t/incomplete-standard-model/831285/3 "2019-03-18T03:10:15Z")
> [@Exapno\_Mapcase](#): > > C’mon guys, get with it. I want to tell him to check his sock drawer but I can’t until there’s a serious answer. > > How about a serious question? Are you asking whether the spaces beneath the Higgs Boson need to be filled in? I think that’s just an artifact of how they decided to arrange the graphic. The six quarks all get paired with the gluon, e.g. because they carry the strong force. The four gauge bosons represent only three forces, because the W and Z bosons both are carriers of the weak force. That’s not obvious when compacted this way. So while there might be more scalar bosons, the chart says nothing about their lack. I think you’re right, but I was waiting for the real physics guys to turn up and help out. This chart shows how the particles relate and is more symmetrical [Standard Model - Wikipedia](https://en.wikipedia.org/wiki/Standard_Model#/media/File:Elementary_particle_interactions_in_the_Standard_Model.png) ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [March 18, 2019, 3:22am UTC](https://boards.straightdope.com/t/incomplete-standard-model/831285/4 "2019-03-18T03:22:46Z")
In addition, the graphic is missing the graviton, which, if it exists, would be a tensor boson, with spin 2. ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [March 18, 2019, 6:42am UTC](https://boards.straightdope.com/t/incomplete-standard-model/831285/5 "2019-03-18T06:42:42Z")
> [@Exapno\_Mapcase](#): > > In addition, the graphic is missing the graviton, which, if it exists, would be a tensor boson, with spin 2. ?? There is no gravity in the Standard Model. ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [March 18, 2019, 3:32pm UTC](https://boards.straightdope.com/t/incomplete-standard-model/831285/6 "2019-03-18T15:32:31Z")
> [@DPRK](#): > > ?? > > There is no gravity in the Standard Model. That’s why I said “if it exists.” Nobody’s been able to make the theory work so it’s not currently part of the SM. However, it’s more likely that in the end a tensor boson needs to be added than more scalar bosons. Just a side comment on why the appearance of the graphic can’t be taken as being a meaningful guide to its extension. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [March 18, 2019, 4:31pm UTC](https://boards.straightdope.com/t/incomplete-standard-model/831285/7 "2019-03-18T16:31:34Z")
> [@Exapno\_Mapcase](#): > > That’s why I said “if it exists.” Nobody’s been able to make the theory work so it’s not currently part of the SM. However, it’s more likely that in the end a tensor boson needs to be added than more scalar bosons. > > Just a side comment on why the appearance of the graphic can’t be taken as being a meaningful guide to its extension. It’s not just that a graviton has yet to be detected (and a single graviton will, in all likelihood, never be directly observed using electromagnetic interactions); the Standard Model is based upon grand unified quantum field theory (of electroweak and strong interactions) using SU(3)xSU(2)xU(1) gauge symmetry. The table of quarks, leptons, and bosons that you see is just a schematic representation of fundamental particles grouped into logical just like the periodic table of chemical elements; it’s not any kind of predictive tool, and the graviton, if it exists, would fall into a category outside the schematic table, presumably in its own row under the column of gauage bosons. Integrating gravitation into the other physical interactions would require a radical extension of the Standard Model or more likely a fundamental retooling of physics as we know it, e.g. something like M-theory, and may well result in whole new families of previously unseen exotic particles (although no sign of supersymmetric particles has thus far been seen at the LHC). The Standard Model appears ‘complete’ as a general electronuclear theory in predicting all of the necessary fundamental particles although we are limited as to how realistically interactions can be simulated (which would require Grand Unified Theory), but it does not even attempt to address general relativity (so-called “Einstein gravity”), and because of the difference in scale of strength there is practically no scenario in which we could directly test interactions between gravitons and other fundamental particles. Some physicists have actually expressed the belief that there is either no symmetry between gravitation and the other forces, or even if there is, we will never be able to integrate them without some kind of radical retooling of quantum mechanics. Stranger ---
**Author:** ![OldGuy](https://avatars.discourse-cdn.com/v4/letter/o/3bc359/32.png) [@OldGuy](https://boards.straightdope.com/u/OldGuy)\ **Post date:** [March 18, 2019, 6:08pm UTC](https://boards.straightdope.com/t/incomplete-standard-model/831285/8 "2019-03-18T18:08:28Z")
> [@Andy\_L](#): > > This chart shows how the particles relate and is more symmetrical [Standard Model - Wikipedia](https://en.wikipedia.org/wiki/Standard_Model#/media/File:Elementary_particle_interactions_in_the_Standard_Model.png) If I read that chart correctly, it says that the Higgs interacts with the electron and its heavy versions, but none of their neutrinos. If that’s correct, then how do the neutrinos get there masses? I thought it was the Higgs field that gave particles their masses. ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [March 18, 2019, 6:17pm UTC](https://boards.straightdope.com/t/incomplete-standard-model/831285/9 "2019-03-18T18:17:59Z")
> has a discussion of this very issue. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [March 18, 2019, 8:26pm UTC](https://boards.straightdope.com/t/incomplete-standard-model/831285/10 "2019-03-18T20:26:08Z")
The Higgs mechanism isn’t responsible for all mass, or even for most mass, or even for most of the mass we’re familiar with. It’s just one of many mechanisms which account for mass. And in some trivial sense, the Standard Model is, almost by definition, complete. It’s a description of that particular set of particles. If any other particles exist (like, say, the graviton), they’re not part of the Standard Model. It’s like asking if there are any pages of _Lord of the Rings_ that aren’t part of the published book: Well, no, because any pages that aren’t part of the published book aren’t pages of _Lord of the Rings_. But as any Tolkien fan knows, there are oodles and oodles of other pages written by Tolkien about Middle Earth, and many of them have been collected and published and become familiar to readers. It may well be that we’ll discover more particles someday-- In fact, it’d be surprising if we didn’t. And as we become more familiar with how those particles work, we’ll probably change the definition of “standard model” to include them (for instance, it wasn’t that long ago that the Higgs was not described as part of the Standard Model). But they’re not part of the Standard Model as it now exists.