ABSTRACT
The beauty and clearness of the dynamical theory, which asserts heat and light to be modes of motion, is at present obscured by two clouds. This chapter sees how quantum mechanics kicks in when matter and forces are described at small distances. How perspective is changed by introducing quantisation of energy. How quanta move through space-time in the form of granular waves. What the difficulties were and still are in interpreting quantum mechanics. In a classical ideal gas with massive particles, the energy of the particles is distributed according to a Maxwell-Boltzmann distribution. Equilibrium is established by the particles themselves: they collide with each other, exchanging energy and momentum in the process. Spectroscopic separation of wavelengths was achieved with specialised prisms and lenses made of halite, fluorite and sylvine, which transmit light efficiently up to far infrared wavelengths.
