in the epochs of the very early universe, the different forces separated from each other in succession. if this is true then at one point there was an electroweak force. and before that, there was the electronuclear force, and before that all four were unified.

my question is about what order the different particles of the standard model came into existence. but the question is in light of the unified nature of the forces.

how did the electroweak force behave before it split? where were w-bosons and photons at this time? where were the leptons? if the forces were "unified," were the particles unified as well? was there a boson that mediated the electroweak interaction? a boson that no longer exists?

and likewise, was there another boson that mediated the electronuclear force when the strong force was still unified with the electroweak?

i have a very rudimentary understanding, but my current framework has me thinking along these lines.

the higgs boson would had to have come first, in order for anything else to even occupy spacetime. then some sort of 4-force boson and 4-way unified fermions? then gravitons split off, leaving a 3-force boson. then the gluons split,leaving a two-force boson and quarks and leptons. and finally the w-bosons and photons separated, allowing for all the elementary and composite particles we have now.

how far off am i?

do we know what particles came in what order and during which epochs?

  • $\begingroup$ Why the other particles can't occupy space without the Higgs? Only after the Higgs potential broke, particles acquired mass. Like the W- and Z- particles, while gluons and photons and gravitons remained massless. I think all particles existed in a massless state, interacting by the unbroken force field. One by one they split off giving the massless graviton and massless stringweakelectrofirce particles, from which the massless gluons and massless electroweak force emerged, and at last the massive weak and massless photon. Im not sure when the matter particles got their mass. $\endgroup$
    – Gerald
    Commented Aug 18, 2022 at 18:54
  • $\begingroup$ See en.wikipedia.org/wiki/X_and_Y_bosons & physics.stackexchange.com/q/341411/123208 $\endgroup$
    – PM 2Ring
    Commented Apr 1 at 11:15

2 Answers 2


You are assuming that the four fundamental forces existed separated for all the time to add up to the standard model, whereas the point is the opposite: they separated by coalescing (getting unified) into one force from the very beginning.

The problem is that both baryogenesis (the standard theory of why there is any matter at all in the universe) and a non-zero cosmological constant each greatly require supersymmetry or other postulates that Higgs bosons and W and Z particles we observe almost never decay into each other. (You can't have CPT violation without its effects showing up in radioactive decay processes, either.)

Unless you are willing to make certain arbitrarily precise tuning assumptions about the state at the Big Bang, you either need to posit physics very different than the SM (which predicts hugely sensitive ways the very early universe could be heavily distorted from this collection of SM particles) or postulate some BSM physics that resonantly causes a separation of the world such that almost no prior SM processes can change from a symmetric configuration.

I'm not aware of any proposed model of the early universe that fits this bill - the standard BBN model along with standard post-BBN-produced-matter-and-energy production models do not between them account for the entire universe.

  • $\begingroup$ But, IF we define fundamental particles by their values/properties: mass, charge, color, spin AND those are expressions of how they interact with the four forces, HOW did electrons/positrons exist as defined, before their DEFINING forces operated as they do now? If particles that are now e-/e+ existed before charge, they'd be chargeless leptons like neutrinos, with different masses. They'd be a novel species, a step closer to symmetry with neutrinos. Before gravity separated, they'd be more symmetrical, sharing even their spacetime coordinates, identical in substanc/location. A singularity? $\endgroup$ Commented May 3 at 13:40

The current mainstream cosmological model is the Big Bang. The model uses our particle physics standard model in order to project back in time, and see if the predictions fit the astrophysical observations. Here the symmetry breaking order in the BB model is summarized:

big bang timeline

It presupposes that a unified quantum field theory exists including gravity, which is not true because gravity is not definitively quantized, only effective models exist.It gives the order of the symmetry breaking according to the existing BB model.

All the elementary particles in the standard model of particle physics are hypothesized to exist , as the SU(3)xSU2xU(1) symmetry has the location of the particles whether symmetry is broken or not.

So the particles in the present theory are always there, whether mass less before symmetry breaking, or massive after.

  • $\begingroup$ When did the matter particles acquire mass? For example, did the electrons acquire mass at the breaking of SU(2)×U(1)? Or only the W and Z? $\endgroup$
    – Gerald
    Commented Aug 18, 2022 at 18:56
  • $\begingroup$ Mass comes with the higgs mechanism en.wikipedia.org/wiki/Higgs_mechanism. see also physics.stackexchange.com/questions/253762/… $\endgroup$
    – anna v
    Commented Aug 18, 2022 at 19:16
  • $\begingroup$ But aren't it only W- and Z- acquiring mass in the electroweak symmetry break? $\endgroup$
    – Gerald
    Commented Aug 18, 2022 at 19:24
  • 1
    $\begingroup$ AFAIK in the mainstream physics model the Higgs mechanism is unique for the breaking of the weak interactions $\endgroup$
    – anna v
    Commented Aug 19, 2022 at 3:13
  • 1
    $\begingroup$ @blacktopshaman Isn't a particle's mass an intrinsic, defining property? No, it is an emergent property. $\endgroup$
    – Ghoster
    Commented Nov 15, 2023 at 6:03

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