WHAT IS THE FUTURE OF COSMOLOGY? - cont.
In fact, there are other reasons to expect that space and time should be self-organized. Systems which are self-organized turn out to be complex systems. What is a complex system? What is complexity? One approach to this question, which Julian Barbour and I have developed, is to define the complexity of a system in terms of the variety of the interactions of the parts of the system. Roughly speaking, the more variety a system has, the easier it is to distinguish the parts of the system from each other by describing each of their neighborhoods. In these terms, a complex universe is one in which the view from every place is different from the view from any other place. But, as I argued at the beginning, space itself is defined only by the relationships among things. This means that the more complex a universe is, the easier it is to define space in terms of relationships. This means that there is a deep and fundamental connection between the idea that space and time are to be defined solely in terms of relationships and the idea that the world is a complex system whose structure is to be explained, in part, by its having undergone processes of self-organization.
The first is the key idea behind general relativity, the second the idea behind modern biology. What joins them is that in the end both sets of ideas make sense as descriptions of systems, like the universe or life on earth, that must structure themselves from the inside, without being made or observed from the outside.
But these themes are not only essential for understanding what is happening in cosmology and fundamental physics. More and more, I have the experience of meeting people in other fields who talk to me about the importance of the themes of relationalism, variety, evolution and self-organization in their own fields. First, in science, one sees the same constellation of themes reflected in the work of people such as Per Bak and Stuart Kauffman, who are attempting to understand the principles of self-organization at work in biology and other complex systems, such as the economy. One even sees these themes in the work of pure mathematicians, such as Louis Crane, John Baez and others, who are exploring the use of category theory as the basis of understanding topology, algebra and logic. Beyond science, if one reads political thinkers such as Drucilla Cornell or Roberto Unger; explores the architectural adventures of Frank Geary and Charles Jenks; or looks at the sculpture and painting of artists like Saint Clair Cemin or Donna Moylan, one sees they also are captivated by the idea that the world is constructed from evolving relationships rather than eternal and static absolutes.
Of course, this does not mean that these ideas are right; only observation and experiment can, in the end, tell us that. But it does mean that the late twentieth century pessimists, the postmodernists and social constructivists, and the end-of-this-and-that-ists have it completely wrong. We enter the 21st century with new ideas and wide horizons, with much to do and everything to talk about.