On the hunt for answers to the bigger questions

I am a Research Analyst, aka Pre-Doctoral Fellow, at the Computational Center for Astrophysics at Flatiron Insitute in New York City, as well as a PhD student in cosmology at Stockholm University, supervised by Prof. Jens Jasche. My research focuses on reconstructing the primordial density fluctuations of the Universe through field-level inference. By combining Bayesian forward modeling with modern machine learning, I develop methods to recover the initial conditions of cosmic structure formation from galaxy survey data. Recently, I have introduced neural network–based emulators into the BORG inference framework and proposed a gradient-free approach, LULO, which uses deep learning as a neural optimizer for fitting non-differentiable cosmological simulators to data. I am an active member of the Aquila Consortium and the Simons Collaboration on Learning the Universe, and I have recently been awarded a pre-doctoral fellowship at the Center for Computational Astrophysics in New York, where I will join as a Research Analyst in spring 2026.

The important thing is not to stop questioning. Curiosity has its own reason for existence. One cannot help but be in awe when he contemplates the mysteries of eternity, of life, of the marvelous structure of reality. It is enough if one tries merely to comprehend a little of this mystery each day.

Albert Einstein

Current Research (2022–)

Research in Machine Learning the Initial Conditions of the Universe, at Stockholm University. If you're not a cosmologists, you may enjoy the Popular Science page, where I've tried to make my research more accessible.

News and Recommendations

I’m very passionate about outreach and science communication. On this page, you can read more about the outreach program Fysikshow, which I had the privilege of leading from 2023 to 2025. I also share some of my favorite visualizations—a VR headset experience that lets you fly through our digital universe and a star trail image of the night sky. You’ll also find videos and links to my latest conference participations and talks, where I present our work on reconstructing the Universe’s initial conditions.

Previous Research (2019–2022)

Such as my master thesis project – A Machine Learning Approach for Comprehending Cosmic Expansion. Other research includes the development of a statistical software package in python for spectral timing analysis at Stockholm University, and the development of a safety filter for quadrotor obstacle avoidance at Caltech.

Larger Course Projects (2018–2021)

Multiple courses at the Engineering Physics program at KTH had a larger project as the final examination of the course. Here I present some of the major projects completed.

Contact Information

Ludvig Doeser – ludvig.doeser@fysik.su.se
PhD Student in Cosmology
Department of Physics, Fysikum
Stockholm University