of the laws governing the transformation
of heat energy
to and from other forms of energy, thus of the efficient design
and working of heat engines (such as the gas engine
and the steam engine). Its 3+1 laws are as follows: (1) First law: No form
of energy can be created or destroyed but may be transformed from one to another. Therefore the total energy in the universe
remains the same. (2) Second law: It is impossible for heat to travel
from an object
at a lower temperature
to another object at a higher temperature. Stated by the German physicist Rudolf Clausius (1822-1888) in two parts as, "Heat cannot be transferred from one body to a second body at a higher temperature without producing some effect," and "The entropy
of a closed system
increases with time." (3) Third law: It is impossible to reduce any system
to a level of absolute temperature or 0 Kelvin (-273.15°C or -459.67°F).
(0) Zeroth law of thermodynamics
(that underlies all the above laws): If two systems are in thermal equilibrium
with a third system, all three systems are in thermal equilibrium with one another.