I am a Senior Researcher at the IBS Center for Theoretical Physics of the Universe Cosmology and Gravity group in Daejeon, Korea. My main research interests include the theory and phenomenology of spacetime-symmetry breaking in gravity and cosmology, which I explore using effective-field theory techniques. I am also interested in early-Universe physics, cosmic tensions, and the mathematics of group theory. One of my current long-term projects focuses on Post-Newtonian theory and the generation of gravitational waves by compact sources in the presence of spacetime-symmetry breaking.

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  • 9 July 2024:My paper on no-go results in gravity with explicit spacetime-symmetry breaking appeared on arXiv
  • 7-12 July 2024:I will discuss some recent results and represent LECS at the LISA Symposium 2024 in Dublin, Ireland
  • 30 April 2024: My paper on dynamical dark energy and spacetime-symmetry breaking was accepted in Physics of the Dark Universe. A preprint version can be accessed here


  • I am co-chair of the Early-Career Scientist working group of the LISA (Light Interferometer Space Antenna) consortium, where I also contribute to the Fundamental Physics and Cosmology working groups.

  • I am on the council of GWECS (Gravitational-Wave Early Career Scientists), where I am also a member of the Science & Research and Career Opportunities offices.

Selected Papers

  • “Reexamining aspects of spacetime-symmetry breaking with CMB polarization”, Nils A. Nilsson and Christophe Le Poncin-Lafitte, Phys.Rev.D 109 (2024) 1, 015032, arXiv.
  • “Spacetime symmetry breaking effects in gravitational-wave generation at the first post-Newtonian order”,Nils A. Nilsson and Christophe Le Poncin-Lafitte, Phys.Rev.D 109 (2024) 2, 024035, arXiv
  • “Explicit spacetime-symmetry breaking and the dynamics of primordial fields”, Nils A. Nilsson, Phys.Rev.D 106 (2022) 10, 104036, arXiv
  • “3+1 formulation of the standard model extension gravity sector”, Kellie O’Neal-Ault, Quentin G. Bailey, Nils A. Nilsson, Phys.Rev.D 103 (2021) 4, 044010, arXiv
  • “Hořava–Lifshitz cosmology in light of new data”, Nils A. Nilsson and Ewa Czuchry, Phys.Dark Univ. 23 (2019) 100253, arXiv

Career timeline

2024 - Present
Senior Researcher @ CTPU-CGA, Institute for Basics Science, Daejeon, Korea
2022 - 2024
CNES Postdoctoral Fellow @ SYRTE, Observatoire de Paris, France
2021 - 2022
Postdoc @ the Centre for Quantum Spacetime, Sogang University, Seoul, Korea
Ph.D. in Physical Sciences @ the National Centre for Nuclear Research, Warsaw, Poland


In my free time, I enjoy rock climbing and board games.