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You can google the phrase "Standard Model" or look it up in any physics book you want, and there will always be a table labeled "Standard Model" that shows all

You can google the phrase "Standard Model" or look it up in any physics book you want, and there will always be a table labeled "Standard Model" that shows all the particles, which relate to the 4 fundamental forces (carriers), charges, spins, masses, etc. I'm sure you're familiar with this chart. The graviton is on that chart and is specifically describing gravity based on each mass value of each particle (hardly "silence" there). I mean literally every particle type has a mass value (even when zero) right? Is that silence? The general laymans meaning of "Standard Model" means everything in physics that is referenced on that chart (including gravity), and that's how I meant it. However, what YOU apparently mean by "silent on gravity" is referencing the fact that the Standard Model is incomplete for gravity, because General Relativity is not yet accounted for. I should've realized you might be referring to the lack of any unified field theory, but I didn't. If you had said "doesn't fully explain" rather than "is silent on", it would've sounded perfectly fine to me.

raattgift 10y ago
No, what I mean is that there is no gravitational term in any formalism of the Standard Model, and never has been. Its Lagrangian does not include a kinetic or interaction term whereby the spectrum of the Standard Model can include a graviton. Gravity is simply absent from the mathematics of the Standard Model, which is a specific quantum field theory. You can certainly describe gravitation using a massless spin-2 graviton, and perturbative quantum gravity -- another specific quantum field theory -- does exactly that, and is a perfectly fine effective field theory that entirely matches General Relativity absent superposed sources and outside of strong gravity (which is defined by the EFT's renormalization group flow). You can add this graviton to a particle zoo. But then it's not the particle zoo of the Standard Model, any more than writing down an "action of everything"[1] gives the action of the Standard Model. > The general laymans meaning of "Standard Model" means everything in physics that is referenced on that chart (including gravity), and that's how I meant it. is only correct if you underline the "how I [mean] it" part and make that central to evaluating the sentence's truth. It's hard to disprove solipsistic physics, though, and rarely interesting. Additionally, > which relate to the 4 fundamental forces (carriers) ... I'm sure you're familiar with this chart. Sure, but there are several such charts, and they're not all the same. Here's one from Fermilab and SLAC, institutions that are pretty familiar with the Standard Model: http://www.symmetrymagazine.org/standard-model/ http://www.symmetrymagazine.org/standard-model/ (There's no graviton in it). Fundamental forces come from fundamental interactions, but there is no force police force enforcing a law that there are four of them or that the carriers are gauge bosons in a particle zoo. The Higgs interaction can be treated as a force[2] and its mediator is a scalar boson rather than a gauge boson, so does the Standard Model have four fundamental forces? One can take differing views of the electroweak interaction above 80-90 GeV: does the Standard Model have only two fundamental forces? One can certainly treat Einstein gravity as at least a d'Alembert force arising from the affine connection; but alternatively one could take the position that d'Alembert forces generically depend on a choice of frame of reference and on that basis they cannot be fundamental. Is gravity a force? You get a different answer from Newton (yes) than you do from either Einstein (yes, but it's fictitious) or Misner, Thorne & Wheeler (mu, there is only spacetime geometry). So an argument that as there are four fundamental forces there must be four force carriers is on shaky ground to start with. Even if we were to accept that, it does not follow that all the forces in question relate to the local symmetries of the Standard Model. [1] For example, Carroll's "core theory" here: http://www.preposterousuniverse.com/blog/wp-content/uploads/2013/01/Everyday-Equation-1024x353.jpg http://www.preposterousuniverse.com/blog/wp-content/uploads/... [2] as discussed at last year's Moriond EW, for example, the Higgs force can be measured using atomic spectroscopy: https://indico.in2p3.fr/event/12279/session/7/contribution/149/material/slides/0.pdf https://indico.in2p3.fr/event/12279/session/7/contribution/1...
- raattgift 10y ago
  Since this got me wasting time on Symmetry Magazine, I'll leave this here: http://www.symmetrymagazine.org/article/the-deconstructed-standard-model-equation http://www.symmetrymagazine.org/article/the-deconstructed-st... It's all interesting, and the first two paragraphs are directly relevant.
- ClayFerguson 10y ago
  Most people consider the 4 fundamental forces to be 'part of' the Standard Model, even if the field equations are not complete. But like I said, i did understand what you meant by 'silent on gravity' after your first clarification.
  - raattgift 10y ago
    > Most people consider the 4 fundamental forces to be 'part of' the Standard Model Well, you've convinced me that you believe that.
    - ClayFerguson 10y ago
      Like most 'debates' on HN, the entire thing boils down to whose definition of a word is correct. If I had stated something incorrect about actual physics, you'd have pointed it out. You never did, because I never did.
    - ClayFerguson 10y ago
      Here's an example article just published that shows plenty of people use Standard Model in a way that assumes gravity to be part of what's encompassed by that term. https://www.nytimes.com/2017/02/20/science/hubble-constant-universe-expanding-speed.html https://www.nytimes.com/2017/02/20/science/hubble-constant-u... Standard model is conventionally used in modern times to mean "the current understanding of physics"

raattgift 10y ago

No, what I mean is that there is no gravitational term in any formalism of the Standard Model, and never has been. Its Lagrangian does not include a kinetic or interaction term whereby the spectrum of the Standard Model can include a graviton. Gravity is simply absent from the mathematics of the Standard Model, which is a specific quantum field theory. You can certainly describe gravitation using a massless spin-2 graviton, and perturbative quantum gravity -- another specific quantum field theory -- does exactly that, and is a perfectly fine effective field theory that entirely matches General Relativity absent superposed sources and outside of strong gravity (which is defined by the EFT's renormalization group flow). You can add this graviton to a particle zoo. But then it's not the particle zoo of the Standard Model, any more than writing down an "action of everything"[1] gives the action of the Standard Model. > The general laymans meaning of "Standard Model" means everything in physics that is referenced on that chart (including gravity), and that's how I meant it. is only correct if you underline the "how I [mean] it" part and make that central to evaluating the sentence's truth. It's hard to disprove solipsistic physics, though, and rarely interesting. Additionally, > which relate to the 4 fundamental forces (carriers) ... I'm sure you're familiar with this chart. Sure, but there are several such charts, and they're not all the same. Here's one from Fermilab and SLAC, institutions that are pretty familiar with the Standard Model: http://www.symmetrymagazine.org/standard-model/ http://www.symmetrymagazine.org/standard-model/ (There's no graviton in it). Fundamental forces come from fundamental interactions, but there is no force police force enforcing a law that there are four of them or that the carriers are gauge bosons in a particle zoo. The Higgs interaction can be treated as a force[2] and its mediator is a scalar boson rather than a gauge boson, so does the Standard Model have four fundamental forces? One can take differing views of the electroweak interaction above 80-90 GeV: does the Standard Model have only two fundamental forces? One can certainly treat Einstein gravity as at least a d'Alembert force arising from the affine connection; but alternatively one could take the position that d'Alembert forces generically depend on a choice of frame of reference and on that basis they cannot be fundamental. Is gravity a force? You get a different answer from Newton (yes) than you do from either Einstein (yes, but it's fictitious) or Misner, Thorne & Wheeler (mu, there is only spacetime geometry). So an argument that as there are four fundamental forces there must be four force carriers is on shaky ground to start with. Even if we were to accept that, it does not follow that all the forces in question relate to the local symmetries of the Standard Model. [1] For example, Carroll's "core theory" here: http://www.preposterousuniverse.com/blog/wp-content/uploads/2013/01/Everyday-Equation-1024x353.jpg http://www.preposterousuniverse.com/blog/wp-content/uploads/... [2] as discussed at last year's Moriond EW, for example, the Higgs force can be measured using atomic spectroscopy: https://indico.in2p3.fr/event/12279/session/7/contribution/149/material/slides/0.pdf https://indico.in2p3.fr/event/12279/session/7/contribution/1...

raattgift 10y ago
Since this got me wasting time on Symmetry Magazine, I'll leave this here: http://www.symmetrymagazine.org/article/the-deconstructed-standard-model-equation http://www.symmetrymagazine.org/article/the-deconstructed-st... It's all interesting, and the first two paragraphs are directly relevant.
ClayFerguson 10y ago
Most people consider the 4 fundamental forces to be 'part of' the Standard Model, even if the field equations are not complete. But like I said, i did understand what you meant by 'silent on gravity' after your first clarification.
- raattgift 10y ago
  > Most people consider the 4 fundamental forces to be 'part of' the Standard Model Well, you've convinced me that you believe that.
  - ClayFerguson 10y ago
    Like most 'debates' on HN, the entire thing boils down to whose definition of a word is correct. If I had stated something incorrect about actual physics, you'd have pointed it out. You never did, because I never did.
  - ClayFerguson 10y ago
    Here's an example article just published that shows plenty of people use Standard Model in a way that assumes gravity to be part of what's encompassed by that term. https://www.nytimes.com/2017/02/20/science/hubble-constant-universe-expanding-speed.html https://www.nytimes.com/2017/02/20/science/hubble-constant-u... Standard model is conventionally used in modern times to mean "the current understanding of physics"