Thermodynamics is a branch of natural science in physics which deals with the detailed study of movement of heat between different objects. It also concerns with the external and internal change in objects by defining macroscopic variables (such as temperature, internal energy, entropy, volume and pressure) that characterize materials and radiation, and explains how they are related and by what laws they change with time. It is normally analyzed via statistics (mathematics) to determine the motion of particles.

Thermodynamics assists in describing the average behavior of very large numbers of microscopic constituents such as atoms and helps it relate to the world we see through. Thermodynamics also addresses to a broad section of science and engineering - such as engines, phase transitions, chemical reactions, transport phenomena and black holes. Thermodynamic calculations are also vital for further terrains of physics and for chemistry, chemical engineering, aerospace engineering, mechanical engineering, cell biology, biomedical engineering, materials science and economics as well.

Thermodynamics is subdivided into 4 categories, out of which 'Classical Thermodynamics' and 'Statistical Thermodynamics' are counted as the two main categories. The other two are; 'Local Equilibrium Thermodynamics' and 'Generalized' or 'Extended Thermodynamics'.

Thermodynamic system is the main attraction in thermodynamics. A thermodynamic system is an object or a group of objects. Also all thermodynamic systems carry two kinds of properties; extensive and intensive. A stone brick is a good example of a thermodynamic system as it is combined of several atoms who all have distinguished properties. In a brick the extensive properties are the ones which it gets by adding up all the atoms. Things like volume, energy, mass and charge are extensive because two of the same brick put together have twice as much mass as one brick. The intensive properties of the brick are the ones it gets by looking at the average over all atoms. Things like temperature, pressure and density are intensive because two of the same brick still have the same temperature as one brick alone.


Thermodynamics stands by four laws that states how energy can be moved between two objects in the form of heat.

Zeroth Law of Thermodynamics:
If two systems have equal heat flow back and forth and one of the two systems has equal heat flow back and forth with another system, all three systems have equal heat flow with each other.

First Law of Thermodynamics:
An increase in energy in a system is the same as the energy given to a system in the form of heat.

Second Law of Thermodynamics:
Given a pair of systems touching with different temperatures, heat will flow from hot to cold until the temperature of the systems becomes equal.

Third Law of Thermodynamics:
When a system has a temperature of 0 Kelvin, absolute zero (the lowest temperature), the entropy (energy that cannot be used to do work) is at 0.


In earlier times, thermodynamics was only studied to make more efficient steam engines. Gradually people started applying thermodynamics on other things as well and nowadays thermodynamics is widely used from making engines to studying about black holes.

Scientists use thermodynamics for many reasons. One of them is to develop better engines and refrigerators and another is to understand the properties of everyday materials so that things can be made stronger in the future. Thermodynamics is also used in chemistry to explain which reactions will work and which will not. Thermodynamics is powerful because simple models for atoms work well in explaining the properties of large systems like bricks.


For more detailed study on 'Thermodynamics', you may refer to Thermodynamics; Wikiepedia.