The Law of Energy Conservation & Transformation
The first law of thermodynamics says that energy can neither be created nor be destroyed, it can only be transferred from one form to another.
Energy is the ability to do work. In an isolated system, this ability to do work merely transforms from one form to another. No new energy is created nor destroyed in the unfolding of the system’s thermodynamics. All of the energy in the system came from somewhere or something else, and all current energy in the system continues to transfer through and between its various states and parts, never increasing or decreasing in total energy.