A review of the historical development of cosmology suggests that there are two approaches. One starts with the special and general theories of relativity and proceeds along the lines of theoretical physics; the other takes account of the fact that the universe consists of matter and that the chemical, physical and thermodynamic properties of matter need to be considered. The second approach is of paramount importance for two reasons; first because facts based on experiments in chemistry and physics have accumulated over two centuries and have a sound provenance, and second because thermodynamic data provide a means of doing thermodynamic calculations to test the validity of theories on the nature and origin of the universe. The thermodynamic data in question are numerical values of properties of matter such as internal energy, ionization energy and entropy.
When cosmologists say that the Universe was at a temperature of 1010 K when it was one second young, they are making a thermodynamic statement. Temperature is a thermodynamic function. Cosmologists frequently apply thermodynamic equations wrongly and they have the erroneous belief that an expanding gas automatically cools down. The Hot Big Bang Theory stands or falls on its thermodynamic credentials. Cosmologists have entered the realm of Thermodynamics.
This paper analyzes some of the thermodynamic arguments leading to the Hot Big Bang Theory and shows that the theory does not exhibit a valid energy balance.
Thermodynamic calculations are presented with the aid of a Temperature-Entropy Diagram for hydrogen and these calculations together with some graphs show conclusively that the Hot Big Bang Theory violates both the First and Second Laws of Thermodynamics.
An alternative version of the Hot Big Bang Theory that the cooling of the Universe comes about by expanding against the force of gravity ? is disproved by a theorem using the Thermodynamics of an isentropic expansion.
Proponents of the Hot Big Bang Theory are challenged to answer five questions.