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Shanthi
Many years ago, when I was watching my children attending their Karate lessons, and doodling patterns on my sketchbook, another parent who sat next to me saw my drawings and asked me if I had heard of Penrose Tiling. He told me that I should check them out as I might find them interesting. And I did and was floored. Not only was I amazed at the beauty of these patterns and the possibilities but also by Roger Penrose’s many achievements, and I started listening to his talks online. Though most parts of his talks were beyond my understanding, I enjoyed doodling based on what I did understand. His transparencies with drawings of black holes were wonderful and gave me a better understanding of these mysterious objects. I had always wondered if scientists ever came up with scientific ideas inspired by art and it was nice to find out that Penrose was inspired by MC Escher’s work and that he thought visually. Recently as I was working on a project that involved Penrose diagrams, I revisited his tiling patterns and was inspired to try out some of my own patterns. So, it was a pleasant surprise to hear about the Nobel Prize announcement being awarded to Sir Roger Penrose and the two other scientists for their work on black holes.
Pentagon-Overlaps, Pen on Paper, August 2020
Naturally, Leilhae and my conversation began with a chat about the announcement, sharing our thoughts on it and discussing Penrose’s contributions. As we talked about his work on black holes, Leilhae explained about the different kinds of black holes - static and spinning types. She described the shape of the gravitational waves and how scientists try to locate the position of a black hole collision when an event is observed. We also talked about Leilhae’s artwork in which she has attempted to capture the story of the birth of her son from the time of the Big Bang, which captures our origins very beautifully.
Leilhae’s Human Nucleosynthesis
Leilhae
As I was speculating about the circularity of trajectories two weeks ago, the recent news made me wonder about squaring the circle. This week, the Royal academy of a nordic European country decided to offer its most prestigious prize to Roger Penrose, a living legend of Physics and Mathematics. He has been rewarded for his work in black holes, notably proving that stellar collapse, a phenomenon that regularly occurs in the Universe, could lead to the singularities already observed in General Relativity. Penrose, very like Einstein, is a geometer: his work is not only illustrated by diagrams, but visualization seems to be a tool integrating his research process even in its development. Similarly to Feynman diagrams being commonly used by particle physicists, gravitational physicists regularly use Penrose-Carter diagrams to visual causality in spacetime. As those diagrams summarize four dimensions into two, assuming a spherical geometry, the horizontal axis represents traveling in space while the vertical axis represents traveling in time. Light, for which, as Rovelli points, "time never passes at all", travels along the diagonal, towards the edge of the square that symbolize infinities. As I observe this diagram again, I notice how its elegant schematization of spacetime enables me to feel the physical process display in it: massive objects crawl along the space axis as time flies towards the future, while light transperse the manifold towards an infinity that appears like an horizon never reached but always aimed for. The Universe in this squared circle appears absurd, yet supremely beautiful in its laws that we relentlessly try to decipher to understand the logic beneath all our experiences. 
Penrose diagram of an infinite Minkowski universe Credit: Fred the Oyster, Creative Commons
This process of trying to ordinate the chaos of phenomena around us with logic is inherent to the work of the other scientists with whom Penrose shares his award. Genzel, Ghez, and other fellow astrophysicists spent years following the trajectories of stars around the object at the center of the Milky Way to infer its nature. After more than a decade extracting the light of the few stars standing out from the extremely bright area that a galactic core is, they inferred that according to the extremely massive nature of the object, in a very restricted volume of spacetime, it could only be a black hole. This extremely intriguing object, holding in its heart the singularity implying the limitation of the very same theory that predicted it, was not only an artifact of a theory, neither the outcome of a calculation: it became an experimental presence, an body permeating the fabric of our reality. I observe how once again, its presence has been revealed by paths: it is from the motion of stars around the black holes that it existence could be inferred, after Penrose studied the trajectories of particle in spacetime, and Einstein devised the theory of Relativity by considering the time of the clocks of a train passing through a station. Paths, it seems, are not only the daily walks paving our lives obligations, but belong to the very nature of the effects that arise from the law of the Universe and enable us to perceive the machine behind the motion. And when we do, we freeze our knowledge in a diagram summarizing our insights in a visual form - the sense most of us turn to when we need to understand a concept.
Motion of stars around the black hole Sagitarius A*. From: Ghez, A. M., et al. "Full three dimensional orbits for multiple stars on close approaches to the central supermassive black hole." Astronomische Nachrichten: Astronomical Notes 324.S1 (2003): 527-533.
Credit: UCLA Galactic Center Group & Advanced Visualization Lab,
National Center for Supercomputing Applications, University of Illinois
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Shanthi Chandrasekar
Leilhae
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