Readers puzzled by proton’s properties

Proton puzzler

Uncertainty over the proton’s size, spin and life span could have physicists rethinking standard notions about matter and the universe, Emily Conover reported in “The proton puzzle” (SN: 4/29/17, p. 22).

Readers wondered about the diameter (or size) of the proton, which has three fundamental particles called quarks rattling around inside.