Energy is the source value of movement.
Movement can be that of the bodies which surround us (mechanical energy), or can concern elementary particles (molecules, electrons, atoms, photons). In this case, depending on the type of particles concerned, and the type of movement involved, we would speak of chemical, electrical, atomic, radiant, or thermal energy (heat).
If we consider the displacement of bodies which surround us (mechanical energy) as the most “patent” presentation of energy, the other forms are more or less as potent. For example it is difficult to set an object into motion just by heat, whereas electrical energy would achieve this more easily.
is the least efficient form of energy. All the other forms can
convert totally into heat, and not the reverse. The “end of the
world” is supposed to see the disappearance of all traces of heat,
and therefore movement, at – 273 [°C] (- 459.4°F).
Certain would deduce from this that it is absurd to use electricity (an effective form of energy) just for heating, because it would be much more useful for driving engines….
Heating engineers can be consoled by the fact that although heat is the least efficient form of energy, it is also the most essential.