It is likely that Atomic Masses because they are relative will prove the saviour of Physics, because they are the one thing that has not been severely corrupted by Relativistic Correction. read more
The atomic mass (m a) is the mass of an atom. Its unit is the unified atomic mass units (symbol: u, or Da) where 1 unified atomic mass unit is defined as 1 ⁄ 12 of the mass of a single carbon-12 atom, at rest. read more