Editing Elementary particle (section)

== Cosmic abundance of elementary particles ==
{{Main|Cosmic abundance of elements }}

According to the current models of [[Big Bang nucleosynthesis]], the primordial composition of visible matter of the universe should be about 75% hydrogen and 25% helium-4 (in mass). Neutrons are made up of one up and two down quarks, while protons are made of two up and one down quark. Since the other common elementary particles (such as electrons, neutrinos, or weak bosons) are so light or so rare when compared to atomic nuclei, we can neglect their mass contribution to the observable universe's total mass. Therefore, one can conclude that most of the visible mass of the universe consists of protons and neutrons, which, like all [[baryon]]s, in turn consist of up quarks and down quarks.

Some estimates imply that there are roughly {{10^|80}} baryons (almost entirely protons and neutrons) in the observable universe.<ref>{{Cite journal |last=Padilla |first=Antonio |date=2022-08-13 |title=The universe by numbers |url=https://linkinghub.elsevier.com/retrieve/pii/S0262407922014476 |journal=New Scientist |volume=255 |issue=3399 |pages=42–45 |doi=10.1016/S0262-4079(22)01447-6 |issn=0262-4079}}</ref>

The number of protons in the observable universe is called the [[Eddington number]].

In terms of number of particles, some estimates imply that nearly all the matter, excluding [[dark matter]], occurs in neutrinos, which constitute the majority of the roughly {{10^|86}} elementary particles of matter that exist in the visible universe.<ref name=mrob>
{{cite web
 |first=Robert |last=Munafo
 |date=24 Jul 2013
 |title=Notable Properties of Specific Numbers
 |url=http://mrob.com/pub/math/numbers-19.html
 |access-date=2013-08-28 |df=dmy-all
}}</ref> Other estimates imply that roughly {{10^|97}} elementary particles exist in the visible universe (not including [[dark matter]]), mostly photons and other massless force carriers.<ref name=mrob />