;Further, the method of calculating potential energy in light as can be seen in the formula below in [Math.2]. E as is defined here is the potential energy in a substance, T is time the light passes under no gravity, m1 is mass (at its initial value), c1 is velocity of light (at its initial value), and Tk is time the light has passed under no gravity.; ]]> ;In addition, the formula below in [Math.3 ] sets up as derived from [Math.1] and [Math.2]. E as is defined here is the potential energy in a substance or light, m1 is mass (at its initial value), c1 is velocity of light (at its initial value), Tk is time the substance or light has passed under no gravity, and T is time the substance or light passes under no gravity, namely, the existence of time itself.; ]]> ;Moreover, the method of creating reverse time for substances as can be seen in the formula below in [Math.4]. E as is defined here is the potential energy in a substance, T is time the light passes under no gravity, m1 is mass (at its initial value), c1 is velocity of light (at its initial value), and Tk is time the light has passed under no gravity.;When; √{square root over (E/ΣK=1Tm1c1)}−10(1≤K≤T),TK0 [Math.4];And lastly, the method of creating reverse time for light as can be seen in the formula below in [Math.5]. E as is defined here is the potential energy in a substance, T is time the light passes under no gravity, m1 is mass (at its initial value), c1 is velocity of light (at its initial value), and Tk is time the light has passed under no gravity.;When; EΣK=1TC1(1≤K≤T), then TK0 [Math. 5]"/>