08/28/2026
Hello! My name is Camilo Nunez-Reyes, and I am an undergraduate Physics and Math major here at Notre Dame! Throughout this past summer, I had the opportunity to research the Borsuk-Ulam Theorem via Topology. I would describe Topology as the study of Mathematics where shapes and spaces are made out of clay and rubber bands! A common joke in Topology is that Mathematicians can’t tell the difference between a donut and a mug, because they are homeomorphic. This means there exists some function that can grab the mug and transform it into a donut without losing any information, and vice versa without losing any information about the mug or donut! We can say many shapes are homeomorphic if they follow this criterion, for example it is provable that a diamond and a circle are topologically identical! Where Topology becomes particularly powerful is in recognizing that we can prove shapes are homeomorphic in any number of dimensions, allowing for great generality. Because of this trait, Topology plays an important role in many areas of Physics, such as Quantum Field theory, String theory, and even General relativity!
To best understand the Borsuk-Ulam Theorem itself, I invite you to consider a function that flattens a circle onto a number line, like squishing a hula hoop onto the ground. What the Borsuk-Ulam Theorem argues is that, no matter how you flatten this circle onto the number line, two points on this circle when flattened must meet at the exact same point. Of course, being Topology, the Borsuk-Ulam Theorem works with any sphere of dimension n being mapped onto a real space of dimension n. Overall, researching the Borsuk-Ulam Theorem as a sophomore was intellectually challenging, but it was an amazing experience! I would like to give a special thank you to my teammates, Liviu Nicolaescu, mentors, and the Galvin Scholars Program and Notre Dame Science for assisting with the research process!