The discussion of the scales of time in Chapter 10 is important if we want to understand what time means. The relative persistence of structures in the universe simultaneously defines time and is defined by time. Without persistence in one form or another, the concept of system under observation (SUO) makes no sense. But change is the counterbalance to persistence: we would not have evolved into observers without changes in the past.
The time concept as we discuss it in this book, therefore, is predicated on change in two fundamental respects. We will call them relatively external (RE) changes and relatively internal (RI) changes respectively. RE changes are those changes in the universe that were involved in the evolution of living organisms, some of which became primary observers such as physicists and astrophysicists. RI changes are changes in SUOs that those primary observers observe going on.
The expansion of the universe is an RE change because, whilst astronomers ‘observe it’, they have no control over it, no more than they can alter the fossil record in geological strata. They are simply finding out about their own place in the universe. RE changes provide evidence that real observers are endophys- ical, that is, inside the universe. A theory of observers, therefore, will deal with RE changes, whilst RI changes will allow those observers to pretend FAPP (for all practical purposes) that they are external to SUOs and can observe their properties. RE changes affect relative external context (discussed in Chapter 2) whilst relative internal context is needed for the interpretation of RI changes.
Traditionally, physics has focused on RI changes: experiments are not done on observers but by observers. But as science progressed and widened its scope, it started to look beyond RI changes and explored the meaning of RE change, hitherto the domain of metaphysics and religious-based mythology. This advance of science was particularly evident in the nineteenth century, when the sciences of geology and biology started to explore our planet in depth. It became clear not only that our planet had changed, but so had we: humans had evolved over many millions of years.
Evolution, which played a crucial role in the transition from potential SUO into observer, requires a breakdown of persistence in a particular way. In this chapter we look at the processes of life that underpin this transition.