Thermal energy has been accepted as a notion for more than a century.

FREMONT, CA:  Thermal energy accumulates all the kinetic and potential energy contained inside a physical system. This total thermal energy is frequently referred to as a system's total internal energy, and its kinetic energy can be expressed in three ways:

  • Vibrational: The motion of an atom or molecule as vibration. Microwave ovens heat the food and liquids we consume by increasing the molecular vibrations of the meal or beverage.
  • Rotational: The rate at which an atom rotates or spins.
  • Translational: A traveling object follows a straight line. When an archer fires an arrow, the arrow gains translational kinetic energy.

While heat and thermal energy are frequently used interchangeably, they are not identical from a scientific standpoint. Thermal energy is the movement of molecules within a solid or liquid object. Every item or substance has thermal energy—the sun is the solar system's primary thermal energy source.

The transmission of energy from one item or material to another is heat or thermal energy flow. A functioning stovetop, like any pot or kettle placed on it, generates heat energy. The stove can transport heat to the pot, which can transfer heat to the contents of the pot.

What is the exact mechanism through which thermal energy transfers?

Convection is the movement of heat through a fluid or gas. Thermal energy is transferred into the water when one places a pan of cold water over the bonfire. Convection is what occurs, and water gets less thick and rises as it warms. Denser, cooler water sinks and is then warmed by convection currents.

Conduction is how heat is transferred internally within an item, whether solid, liquid, or gaseous. Returning to the pan, conduction happens when heat is transferred from the pan to the handle, thus warming the handle. Conduction is the transfer of thermal energy from a hot object to a cooler object at a lower temperature. Conduction occurs differently when a solid is made of metal or nonmetal.

Radiation, the third mode of thermal energy transmission, occurs via light-speed waves, and it is not reliant on a substance or an item to traverse. The sun is the best example of this type of radiation, which involves the transmission of energy via electromagnetic waves that move through space as light waves or electromagnetic radiation. On a sunny day, one will notice a temperature change as he moves from the shade to the sun. The sun's heat cannot reach Earth via convection or conduction since there are no surfaces to clash with.

Thermal equilibrium occurs when objects at the same temperature inside the same system do not exchange thermal energy only due to their proximity. There is no variation in temperature between the things.