## Viewing the universe from within

Lee Smolin’s earlier book 3 Roads to Quantum Gravity describes so well the fundamental principles of general relativity, foremost of which is the absence of a fixed background in which events play out in the universe and in turn by their interactions define the background in which they occur. In this book, he uses the framework of networks of interacting field lines to characterize this coupled interaction between events and the coordinate systems in which events occur. This Machian concept has appealed to me ever since I began studying general relativity years back and consequently attracted me to the theory of loop quantum gravity formulated by Carlo Rovelli, Lee Smolin, Fotini Markopoulou and their collaborators. However, reflecting back on it now forces me to ponder again on the reasons that behoove us to accept such a concept as an accurate description of our universe and to demand that it be a prerequisite for a good theory of the universe. The theory of general relativity has stood the test thus far in describing our local large-scale environment. There is first and foremost the experiment testing the bending of light from an astrophysical body that passes by another strong gravitational body, which describes the gravitational lensing effect. What about on cosmological scales? As of now, there are a few candidate theories that contest that of general relativity on these scales. Would the failure of the theory of general relativity on these scales negate the concept of background independence as a valid description of the universe? On the mathematical front, much has been and is being developed in the direction of incorporating the idea of background independence and seeing where it will lead the theories based on it in terms of being confirmed by real-world experiments. One such classic that I would need to go through again, this time much more carefully, is by the illustrious Fotini Markopoulou entitled “The Internal Logic of Causal Sets”, which was presented here. Meanwhile, I’m just thrilled by and engrossed in a paper that one of my professors has directed me to recently, which uses the technique of dynamical triangulations (one of the background-independent approaches mentioned above and currently being championed by Renate Loll and her collaborators in the Netherlands) to study the glass transition.

By recent choice, the latter project will be out of my portfolio…but still, it is interesting to see how the method of dynamical triangulations is being employed in such myriad ways.

musafiremes said this on June 20, 2007 at 10:30 pm |