<math>a_0 = {{4\pi\epsilon_0\hbar^2}\over{m_e e^2}}</math>
where:
It has a value of 5.29189379×10-11 m, or about half an angstrom.
... past, they don't call themselves quacks, they can change their name to whatever is trendy at the time, e.g. herbalist. They also promote the distrust of conventional ...