The Planck epoch is the earliest period of time in the history of the universe, before the time passed was equal to the Planck time (tₚ) ; that is from zero to approximately 10⁻⁴³ seconds. The Planck scale is the physical scale beyond which current physical theories may not apply and cannot be used to calculate what happened. At this time scale, every physical quantities like temperature, energies etc were in the range of Planck units values. During the Planck epoch, the temperature and average energies within the universe were so high that even subatomic particles could not form and even the four fundamental forces that shape our universe were combined and formed one unified fundamental force.