The development of thermodynamics in the second half of the 
19th century has had a strong impact on both technology and 
natural philosophy.

It is true that the steam engine for the conversion of heat 
into work existed before thermodynamics was developed as a 
branch of physics. However, the systematic theory improved 
the conversion process, and it succeeded in developing other 
processes essential to modern life, notably refrigeration and 
rectification. So, altogether thermodynamics has provided 
humanity with cheap energy, and cheap fuel, -- consequently 
with cheap, and abundant, and unspoiled food. Thus 
thermodynamics has made populations grow, and life expectancy 
increase beyond anything people could possibly have imagined 
200 years ago. 

At the same time thermodynamics has uncovered the precarious 
balance between determinism and stochasticity which is essential 
to processes on earth, including life. The competition of those 
intentions is described by the doctrine of energy and entropy 
in thermodynamics; energy tends to force a system into one 
single state, and entropy tends to spread the system evenly 
over all possible states. These competing tendencies are weighed by
temperature such that minimal energy determines cold systems and
maximal entropy determines hot systems.

The knowledge gained by thermodynamic research led to quantum 
mechanics, whose rules become predominant at low temperatures, 
and to stellar physics, where temperature is high enough to 
make relativity theory essential.

The expansion of thermodynamic technology and natural philosophy 
is reviewed in the lecture together with the struggles and 
fates of some of the engineers and physicists who pioneered 
the development.