Thermodynamics is the science that deals with energy differences and transfers between systems, and with systematizing and predicting what transfers will take place. Such fundamental topics naturally find application in all branches of science, and have been of interest since the earliest beginnings of science. In general, since we are dealing with energy transfers between systems, most of what follows has to do with what the entities (equilibrium states) are from which and to which energy is being transferred, and the boundaries or walls through which or by which the transfer is effected. It is in these considerations that we first see the differences between natural systems (reality) and our models of these systems. System refers to any part of the universe we care to choose, whether the contents of a crucible, a cubic centimeter in the middle of a cooling magma, or the solar system. Depending on the nature of the discussion, it must be more or less clearly defined and separated (in fact or in thought) from the rest of the universe, which then becomes known as the system's surroundings. At the outset, we will effect an enormous simplification by considering only systems that are unaffected by electrical, magnetic, or gravitational fields, and in which particles are sufficiently large that surface effects can be neglected. Each of these topics can be incorporated into the basic thermodynamic network to be developed, but it is a nuisance to carry them all along from the beginning, and a great deal can be done without considering them at all. More exactly, a great deal can be done if we choose to consider systems where these fields and surfaces play a minor role. Clearly we would not get very far if we tried to understand the solar system without considering gravitational fields. Chemical and geochemical problems however commonly do not need to have these factors included in order to be understood. In science, when a problem or a phenomenon such as the solar system or the boiling of water is said to be understood, what is usually meant is that we have a model of the phenomenon which is satisfactory at some level, and about which virtually all scientists agree.
The Truth behind the Solar System in the Universe