I'm trying to understand the relation between particles and forces during the very early universe--the Planck epoch and subsequent stages as the fundamental forces separated. At what point did the particles related to each of the fundamental forces comes to exist? I think of forces as interactions--i.e. gravity is the interaction between masses. I realize that, as my background is mainly physical chemistry, I may not be asking the "right" question, but maybe someone with more knowledge can see what I'm trying to ask.

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    $\begingroup$ Are you only interested in the four fundamental forces we see today? For example, in the era of “grand unification” there would have been a “grand unified force” carried by a “grand unified gauge boson”, but this force and this particle would be very different from today’s strong, weak, and electromagnetic forces and the gluons, W and Z bosons, and photons that carry them. $\endgroup$
    – G. Smith
    Jun 13, 2019 at 4:06

1 Answer 1


What we know now is the standard model of physics, that has a specific group structure where the known particles and composite ones can be organized. What happens at the time of the Big Bang is speculation, with the knowledge that there is symmetry breaking so that particles acquire mass that individuates them.

Here is a timeline:


The expectation is that at the beginning all particles were there but massless. It shows at what times the symmetry breaking of the gravitational, the strong, and the weak happens .In the standard model it is the weak breaking that introduces masses.

In the standard model there always are particles following the symmetry of the corresponding gauge groups, even though massless , at very early times.


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