The physical state represents each of the stages or forms, which can be physically appreciated through the measurement of certain properties, that a physical system can take in its temporal development. In other words, when a physical system undergoes changes, a physical state has been any of the possible situations that result from said changes.
The concept of physical state is a bit inaccurate and it is possible that it adopts slightly different meanings, depending on the physical theory that is being treated, which is why it is necessary to analyze it within the specific context where it appears. Here are some of the areas of physics where the term physical state is referred to:
In classical mechanics: the microstate of a body refers to a series of notable measurable variables, to fully specify its future temporal development.
In thermodynamics, the macrostate of equilibrium of a body refers to representative situations of the system, characterized by a mixture of physical properties, for example temperature, volume, etc.
In the analysis of dynamic systems, a physical system that is transformed over time and becomes a model through a differential equation. In this area, the line of unknown variables that influences this equation is called “state”.
In quantum mechanics, a state is a mathematical element that synthesizes the maximum achievable information of the system. On the other hand, in relativistic quantum mechanics, states are associated with possible states of space-time.
When physical states are linked to matter, they refer to the physical state in which matter is found in nature, these can be: solid, liquid and gaseous state.
Solid state: a matter in solid state is characterized by presenting its own and absolute form, it is not modified, unless force is applied to it or it is exposed to high temperatures.
Liquid state: a matter in liquid state does not have a specific shape, it can be changed from one container to another without modifying its volume.
Gaseous state: a matter in a gaseous state does not have a defined shape, and like liquids, it adapts to any container where it is placed.
