Why does a system like to minimize its total energy? For example, the total energy of a $H_2$ molecule is smaller than the that of two two isolated hydrogen atoms and that is why two $H$ atoms try to form a covalent bond. According to the classical mechanics, it is the potential energy of a conservative system that is minimum in equilibrium, not the total energy.
[Physics] Why does a system try to minimize its total energy
classical-mechanicsdissipationequilibriumquantum mechanicsstatistical mechanics
Best Answer
The anthropomorphic formulation "tries to" is misleading. Under the effect of ambient noise, matter explores the possible configurations around its current state: e.g., two single hydrogen atoms wiggle around and meet. If they happen to bind, this releases energy which goes away, and we say that the energetic state of this new $H_2$ molecule is lower than what we had. Unless the ambient noise or some experimentalist gives back this energy to the $H_2$ molecule, it will stay so, so there is a net bias toward these states that we describe as having a lower (free) energy.
Let's add that the traditional way to explain this bias (meaning that you need more energy, and thus have less chances, to move from a lower energy state to a higher one than the other way around), is with this schematic of a potential energy analogy: