For questions related to Klein–Gordon equation (or Klein–Fock–Gordon equation or Klein–Gordon–Fock equation). It is a quantized version of the relativistic energy–momentum relation $E^{2}=(pc)^{2}+\left(m_{0}c^{2}\right)^{2}$
The Klein–Gordon equation (Klein–Fock–Gordon equation or sometimes Klein–Gordon–Fock equation) is a relativistic wave equation, related to the Schrödinger equation. It is second-order in space and time and manifestly Lorentz-covariant. It is a quantized version of the relativistic energy–momentum relation $E^{2}=(pc)^{2}+\left(m_{0}c^{2}\right)^{2}$. Its solutions include a quantum scalar or pseudoscalar field, a field whose quanta are spinless particles. Its theoretical relevance is similar to that of the Dirac equation. Electromagnetic interactions can be incorporated, forming the topic of scalar electrodynamics, but because common spinless particles like the pions are unstable and also experience the strong interaction (with unknown interaction term in the Hamiltonian,) the practical utility is limited.
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