Primitive Things

These concepts are so basic that we call them primitives, for everything in later chapters builds on these ideas. You have probably encountered this material before, but our presentation may be new to you. The chapter is divided into primitive things ( 1.1), primitive quantities ( 1.2), primitive changes ( 1.3), and primitive analyses ( 1.4). 

Every thermodynamic analysis focuses on a system— what you re talking about. The system occupies a definite region in space it may be composed of one homogeneous phase or many disparate parts. When we start an analysis, we must properly and explicitly identify the system otherwise, our analysis will be vague and perhaps misleading. In some situations there is only one correct identification of the system in other situations, several correct choices are possible, but some may simplify an analysis more than others. 

A system can be described at either of two levels a macroscopic description pertains to a system sufficiently large to be perceived by human senses a microscopic description pertains to individual molecules and how those molecules interact with one another. Thermodynamics applies to macroscopic entities nevertheless, we will occasionally appeal to microscopic descriptions to interpret macroscopic phenomena. Both levels contain primitive things. 

Beyond the system lies the rest of the universe, which we call the surroundings. Actually, the surroundings include only that part of the universe close enough to affect the system in some way. For example, in studying how air in a balloon responds to being moved from a cool room to a warm one, we might choose the air in the balloon to be 

An interaction is a means by which we can cause a change in the system while we remain in the surroundings that is, an action in the surroundings will cause a response in the system only if the proper interaction exists. Interactions are of two types thermal and nonthermal. A nonthermal interaction connects some variable x in the system to a variable y in the surroundings. This means that x and y are not independent instead, they are coupled by a relation of the form 

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We have reviewed the primitive things, quantities, changes, and analyses that form the basis for thermodynamics as it is developed in this book. Whenever possible we have offered definitions of the primitives, but in every case we moved beyond simple definitions we tried to show why each primitive is important, and we tried to clarify subtleties that often surround certain primitives. 

Now they see things very differently. The chemical composition of the air is not a precondition for life but the result of it. Around two billion years ago, primitive living organisms transformed the atmosphere from one largely devoid of oxygen to one with plenty... 

While a tradition of using minor remedies for things like colds or warts existed, reasonable people left the control of drugs in the hands of the experts. Even patent medicines derived their fundamental cultural status from the implied approval of these groups, or had to go back to their precursors, the medicine men and shamans of primitive days. To this day, television advertisements for patent medicines that will cure headaches, sinus congestion, or "tired blood" are... 

X1+X3, X1+X2+X3. The contradiction between the two accounts can be traced to a conceptual difference. The conceptual schemes of the two accounts use the concept object differently. In the first one object is a primitive category, and its members can only be given by enumeration. In the second one object is defined certain things are primitive objects (these have to be enumerated), and their sums are also objects. Now suppose somebody asks How many objects are there The answer is that the question makes sense only with respect to a particular conceptual scheme. If we are using the first conceptual scheme, the answer is three, if we are using the second one, the answer is seven. So truth is inescapably relative to conceptual schemes. A sentence that is true in one conceptual scheme may be false in another one. 

Let us assume that RNA molecules could grow in primitive solutions up to a maximum length of N nucleotides. These replicating systems could not, individually, grow beyond N, but Eigen was able to prove that things would be different for systems that contained different types of RNA. If the cycles of X individual systems could be... 

We are bound to conclude that the replication paradigm does not offer a plausible model even for postchemical evolution. Of course we cannot exclude that future discoveries might modify such a conclusion, but it would be necessary to discover, among other things, that primitive ribozymes were making replication errors comparable to those of protein enzymes, and this is extremely unlikely. 

One thing I have learned in a long life that all our science, measured against reality, is primitive and childlike - and yet it is the most precious thing we have. 

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