I'm often inspired by reading complex posts from bloggers that I don't really understand. Take, for example, a post from Peter Woit about a young string theorist who questions the psychological reasons why string theory has taken hold of so many scientists, despite its own lack of traditional testability. Woit, one of the more vocal opponents of string theory, mentioned something that caught my eye:
"In his essay, he concentrates on the story of AdS/CFT, the one place that string theory has had some real success. As part of this, he engages in some propaganda himself, quoting me out of context in a misleading way. When I wrote in my book about string theory as a "failed project", I was referring to its failure as an idea about unification, not describing AdS/CFT as a failure."
I'm acquainted with the ideas that string theory is mostly based on abstract reasoning that ties loosely, if at all, to reality, hence the lack of predictions, so this idea that string theory has produced something meaningful struck me as curious. Being someone from which curiosity does not escape easily, I found myself digging around the internet, trying to find anything that translated to undergrad-speak about what this AdS/CFT thing was all about. Finding out the names for what I was searching for was simple: AdS is "Anti de Sitter Space", somehow related to regular "de Sitter Space" by a guy named Willem de Sitter, and CFT is "Conformal Field Theory", a quantum field theory. The "correspondence" between the two is apparently some common ground that they meet on. If any of that sounds confusing, you'll not want to peek at the wikipedia pages for these topics as they're generally just a mess of jargon and equations. But that's where Fine Structure comes in. We'll be discussing the concepts needed to understand just what AdS/CFT is, or at least what we can approximate about the two without a deep understanding of the math behind them.
Without further ado, continue on to our main topic: Understanding Anti de Sitter Space