The concept of energy in physics In physics, the universal law of conservation of energy, which is the basis for the first law of thermodynamics states that energy attached to an isolated system remains over time. However, the theory of special relativity establishes an equivalence between mass and energy by which all bodies, by virtue of being formed of matter, contain energy, moreover, may possess additional energy is conceptually divided into several types according to the properties of the system being considered. For example, the kinetic energy is quantified by the motion of matter, chemical energy as the chemical composition, properties and potential energy as the state of deformation or the position of matter in relation to the forces acting on it and the thermal energy as the thermodynamic state.The energy is not a real physical state, no substance “intangible” but only a scalar that is assigned to the state of the physical system, ie energy is a mathematical abstraction tool or a property of physical systems. For example, one can say that a system with zero kinetic energy at rest. Used as an abstraction of physical systems for the facility to work with scalar quantities, compared with vector quantities such as speed or position. For example, in mechanics, one can fully describe the dynamics of a system in terms of the kinetic, potential, comprising the mechanical energy, which in Newtonian mechanics has retained ownership, that is, be invariant over time.Mathematically, the conservation of energy for a system is a direct consequence of the evolution equations of this system are independent of the instant of time considered, according to Noether’s theorem.