Thermodynamics is the study of the relationships between energy and the activity of a cell. Overall, the laws of thermodynamics govern the way in which cells transform chemical compounds—in other words, how living systems transform one form of energy to another so they can carry out essential life functions.

As in physics, these laws can apply to cells. The first law of thermodynamics states that the total energy of a system and its surroundings will always remain constant (energy cannot be created or destroyed, only transferred). The second law of thermodynamics states that systems tend to become disordered and it usually arises in the form of heat. Another term for this disorder is entropy—a term that refers to the disorder that tends to disrupt cells, or in physics, even the universe.