Are the fundamental constants really constant? Recent investigations have shown that one essential fundamental constant -- namely the mass ratio of protons to electrons -- can have changed only by a ...

Atoms are very small. They have a radius of around 1 × 10 10 metres. This symbol shows that chlorine has 35 particles in the nucleus (protons and neutrons), 17 of which are protons. It also tells us ...

The proton is slightly lighter than previously believed, according to the most accurate measurement so far of this particle’s mass. Protons weigh slightly more than one atomic mass unit (defined as ...