Reality Check
Penultimate Amazing
Think for yourself:No, just a few. Then ask yourself how a point particle can exhibit angular momentum. Do not settle for the "intrinsic" cop-out that offers no answer. Think for yourself, don't let your text books do your thinking for you.
- Electrons are observed to have a magnetic moment.
- They are very small.
- A macroscopic particle as small as the electron with the observed magnetic moment will have a surface that is moving faster than the speed of light.
- This is a problem because Special Relativity states that this cannot happen.
- Thus electrons cannot be macroscopic particles. This has been known since 1925.
Dirac equation solves spin
When the idea of electron spin was first introduced in 1925, even Wolfgang Pauli had trouble accepting Ralph Kronig's model. The problem was not that a rotating charged particle would have given rise to a magnetic field, but that the electron was so small that the equatorial speed of the electron would have to be greater than the speed of light for the magnetic moment to be of the observed strength.
In 1930, Paul Dirac developed a new version of the Schrödinger Wave Equation which was relativistically invariant, and predicted the magnetic moment correctly, and at the same time treated the electron as a point particle. In the Dirac equation all four quantum numbers including the additional quantum number s arose naturally during its solution.