Last night, I gave a talk for the BlinkBl-nk 7 event which happened in Blu Jaz. The talk is a recollection of what culminated to my doctoral thesis in cosmology and some after-thoughts about the subject years later. I share my thoughts on the subject here in this blog and share with you the synopsis of the talk as follows: Modern ideas in theoretical physics revolve around the concept of extra-dimensions and the attempt to unify the four fundamental forces of nature with string theories. Our Universe has been a great & extraordinary laboratory where we formulate hypotheses to disprove these ideas. Can we find extra dimensions via the cosmic microwave background radiation left over from the first three minutes in our Universe? How do we test such an idea using modern satellite technologies like Planck and WMAP? The story started from a doctorate thesis & ends with a satellite that has been recently launched into space.
The way I set up the talk is talk about why we search for extra dimensions in the motivation to find the theory that will unify the four forces of nature: strong & weak nuclear, electromagnetism and gravity. Then I discuss the two different models of theories invoking small (Kaluza Klein) and large extra dimensions (Arkani-Hamed, Dvali and Dimopolous, Randall-Sundrum) and how we can seek them out in the cosmic microwave background radiation, particularly in polarisation signals.
Here are my thoughts from the people who have asked questions on the talk. Perhaps, physics is an osmotic subject where I have learned more and thought about the subject deeper than before. As of today, I have come up with a few different ways to invalidate my original hypotheses on how extra dimensions can affect gravitational waves with theories invoking large extra dimensions. I also answered a question about how I think about modern theories. My thinking about dark matter, dark energy and extra dimensions follows the analogy in the past where ancient philosophers created an elegant theory about the planets and sun moving around the Earth and constructed the epicycles model to force the observations which contradict the theory. In some sense, these things which we cannot explain and the way we invoke extra dimensions, dark energy & matter are the “epicycles” of today. In any case, it also made me remember why I am so deeply passionate about theoretical physics and how I have made a short and modest contribution to the long string of work by other physicists in the field. I am also thankful that I have someone by my side who came for this talk where I can share my joys and passion about my subject for the first time.