Condensed concepts

What do we mean when we say a particular system is "complex"? We main have some intuition that it means there are many degrees of freedom and/or that it is hard to understand. "Complexity" is sometimes used as a buzzword, just like "emergence." There are many research institutes that claim to be studying "complex systems" and there is something called "complexity theory". Complexity seems to mean different things to different people. I am particularly interested in understanding the relationship between emergence and complexity. To do this we first need to be more precise about what we mean by both terms. A concrete question is the following. Consider a system that exhibits emergent properties. Often that will be associated with a hierarchy of scales. For example: atoms, molecules, proteins, DNA, genes, cells, organs, people. The corresponding hierarchy of research fields is physics, chemistry, biochemistry, genetics, cell biology, phys

We all have a worldview, some way that we look at life and what we observe. There are certain assumptions we tend to operate from, often implicitly. Arguably, our worldview is shaped by our experiences: family, friendships, education, jobs, community organisations, and our cultural context (political, economic, and social). A significant part of my life experience has been working in universities as a condensed matter physicist and being part of a broader scientific community. Writing a Condensed Matter Physics: A Very Short Introduction crystallised some of my thoughts about what CMP might mean in broader contexts. I am more aware of how my experience in CMP has had a significant influence on the way I view not just the scientific enterprise, but also broader philosophical and social issues. Here are a few concrete examples. Complex systems. The objects studied in condensed matter physics have many interacting components (atoms). Further, there is an incredible diversity of systems (

There is an interesting Scientific American article by Adam Becker What Is Spacetime Really Made Of? Spacetime may emerge from a more fundamental reality. Figuring out how could unlock the most urgent goal in physics—a quantum theory of gravity It considers two different approaches to quantum gravity (loop quantum gravity and AdS-CFT beloved by string theorists). Compared to some Scientific American articles it is moderately balanced and low on hype. The article has a nice engagement with some philosophers of physics. It is clear to me how loop quantum gravity has a natural interpretation that gravity and space-time are emergent. However, that is not clear for AdS-CFT.  The following paragraph is pertinent. But there are other ways to interpret the latest findings. The AdS/CFT correspondence is often seen as an example of how spacetime might emerge from a quantum system, but that might not actually be what it shows, according to Alyssa Ney, a philosopher of physics at the University of