PX262 - N3 - prediction of antiparticles

the dirac equation describes spin- $ℏ / 2$ fermions like electrons, protons, neutrons, etc.

\begin{matrix} E^{2} = p^{2} c^{2} + m^{2} c^{4} \\ E = \pm \sqrt{p^{2} c^{2} + m^{2} c^{4}} = \pm m c^{2} {(1 + \frac{p^{2}}{m^{2} c^{2}})}^{1 / 2} \end{matrix}

ie. there are also negative energy solutions alongside the positive, which cannot be discarded
instead, there is the dirac sea interpretation, which led to the prediction of antiparticles
dirac proposed that the negative energy states are all occupied
the pauli exclusion principle prevents the positive energy particles from falling into these filled states - 'filled sea'
if a photon with energy, $E = ℏ ω > 2 m c^{2}$ , can excite an electron from a negative energy state, leaving behind a 'hole' in vacuum
the holes correspond to the positive energy antiparticles with opposite charge to the particle states
similarly, there is the prediction of particle-antiparticle annihilation to produce photons
positrons were discovered shortly after the prediction in 1933