What makes up matter in the universe?
Short answer (sort of): Observable matter – up quarks, down quarks, electrons, and electron neutrinos. Two up quarks and one down quark bound by the strong nuclear force make a proton, two downs and one up make a neutron. Experiment shows that an up quark has +2/3 units of charge (an electron has -1), and a down quark has -1/3. Therefore protons are +1, and neutrons are 0. Electrons so far appear to have no further internal structure, and are thus called “elementary” particles, as are quarks. Neutrinos are now believed to have mass, something around one one-billionth the mass of a proton. Long answer: Particle physicists have found many (many!) particles, but almost all of the matter in the universe appears to be composed of those particles mentioned in the short answer. There are also top, bottom, charm and strange quarks, which are much heavier than the up and down, and can combine to make short-lived particles, but they are only present at high energies, and then only for short time
