Recently, I came across a definition of a good theory: it should explain as much as possible, with as few ingredients as possible, and with as much accuracy as possible. I think that is something every serious physicist can relate to. And really, that is what modern theoretical physics is striving for — not just identifying what the universe is made of, but understanding the mathematical framework that makes the laws of nature hang together. That is why the mathematical formulation of quantum field theory is so important. It reveals the hidden structures behind particles, forces, symmetry, and even space itself, and it opens surprising connections to geometry, topology, and information. That is precisely the kind of frontier our guest explores, through research spanning string theory, gauge theory, Seiberg–Witten theory, matrix models, quantum curves, knot theory, and even biophysics through the topology of biomolecules. We’re thrilled to welcome Professor Piotr Sułkowski, a theoretical physicist at the University of Warsaw and a visiting faculty member at Caltech. He leads the Chair of Quantum Mathematical Physics, and his work explores some of the most elegant and fundamental structures in modern physics. Alongside that, he has also been actively involved in making science accessible to broader audiences through outreach projects like “Ask a Physicist.” Professor Sułkowski, it’s such a pleasure to have you with us today.

Important links:

Piotr's Website: https://psulkows.fuw.edu.pl/

Most of what we know about the universe actually comes from what we can’t see.
Only a tiny fraction of the cosmos is made of “normal” matter—the stuff that makes up stars, planets, and us. The rest is a mysterious combination we call dark matter and dark energy, which, although invisible to our telescopes, is absolutely crucial for how the universe expands and how structures form over billions of years.

So how do we even study something we cannot see?

One of the most powerful tools we have is weak gravitational lensing. As light from distant galaxies travels through the cosmic web, the gravity of dark matter gently stretches and shears those galaxy images. The effect on any single galaxy is tiny, almost imperceptible. But when you measure this across millions or even billions of galaxies, a pattern emerges—a subtle cosmic fingerprint that tells us how matter is distributed and how fast the universe is expanding.

This is what our guest today, Dr. Nikolina Sarcevic, works on. She is a cosmologist working at the intersection of data and theory. Nikolina is part of the LSST Dark Energy Science Collaboration, and her work focuses on understanding and modelling the systematics that can bias our measurements—things like how galaxies are intrinsically aligned, how we infer their redshift distributions, and how all of that feeds into weak lensing and dark energy constraints.

So if you’ve ever wondered how we really know that dark energy exists, or what kinds of experiments are used to learn about this invisible matter, you’re going to be thrilled. So with that, let’s go.

Hello Everyone, welcome to The Knowmads Podcast. I'm your co-host Prachi, and I'm your co-host Bhavay. `Chaos' is one of those words that has escaped physics and entered everyday language. We use it to describe messy rooms, traffic, even our inboxes. But in physics, chaos has a very precise meaning, (or it doesnt). Well, classically, chaotic systems are those, that even though they are completely deterministic, they are extremely sensitive to their initial conditions. Even the tiniest change in the initial conditions can lead to wildly different outcomes.\\ But when we move to the quantum world, things become a little strange. When there are no deterministic trajectories in the quantum world, how do we even make sense of chaos.
Our guest today is Dr. Marine De Clerck, a mathematical physicist at the Department of Applied Mathematics and Theoretical Physics at the University of Cambridge. Her work lives right at this intersection of chaos, gravity, and how mathematical structure is built upon quantum chaos. So if you’ve ever heard of the butterfly effect and wondered what chaos really means, you are in for a treat.