Question

what is the smallest unit of the universe?​

Answer 1

the smallest measurement is the plank length.

Answer 2

Electron

                           

Electron is the smallest unit in the universe

                                           

Atom => Atom is made up of 3 particles - Proton, Neutron, Electron.

Atom is the structure of molecules.

Proton => Proton is a positive charged subatomic particle. Nucleus has positive charge because of proton.

- Mass of proton is 1.6*10^-19 coulomb

- The mass of one hydrogen atom is also 1u

                                                             

Neutron =>  Neutron is a neutral subatomic particle which is denoted by symbol n. Neutron is present in the nucleus. It don't have any charge.

- Mass pf one neutron is 1u

- Neutron mass is approximately equal to proton

                                   

Electron => Electron is  a negative subatomic particle, which is having the less mass than proton and neutron

- Mass of electron is 1800 times less than Hydrogen (1u)

- Electron is described by symbol e

                                                 

Photons are also one of the smallest unit in the universe. They are mass less. According to reseaches, they don't have mass