NASA 9.8 on Instagram: "Smallest particles in the universe The smallest particles in the universe, known to scientists, are quarks and leptons. These are fundamental particles, meaning they are not made up of any smaller constituents. Quarks, along with leptons (including electrons), are considered the basic building blocks of matter, according to Consensus. Elaboration: Quarks: These particles have fractional electric charges and are found within protons and neutrons, which are themselves compo