The Plank Era occurred in the first part of the first millisecond after the singularity. Current estimated put it at up to 10⁻⁴³ seconds after the Big Bang. The term “era” is used for this micro-duration as a sort of tip of the hat to Einstein’s Relativity. It reflects a conceptual approach to time that differs from our everyday experience. This speculative era represents the very beginning of the universe, immediately following the singularity. The physics of this period is still not fully understood, as it requires a theory that unifies general relativity and quantum mechanics (quantum gravity). Temperatures and energies were so high that the four fundamental forces (gravity, electromagnetism, the weak nuclear force, and the strong nuclear force) are thought to have been unified.