Does the Universe distinguish between left and right? A tantalizing hint of cosmological parity violation

by Prof. Eiichiro Komatsu (Max Planck Institute for Astrophysics)

Thursday 23 Apr 2026, 15:15 → 16:15 Europe/Stockholm

Parity symmetry is violated in the weak interaction. Do the physical laws behind unsolved cosmological problems, such as dark matter and dark energy, also violate parity symmetry? The polarized light of the cosmic microwave background is sensitive to new physics that violates parity symmetry. In this presentation, we present a tantalizing hint of parity violation in the polarization data from two satellite missions: WMAP and Planck. This signal has also been observed in recent data from the Atacama Cosmology Telescope. Taken together, these findings suggest a cosmological parity violation with a statistical significance of 4 sigma. If this signal is confirmed in the future with higher statistical significance, it would have profound implications for the elusive nature of dark matter and dark energy.

About the Speaker:

Prof. Komatsu is Director of the Department of Physical Cosmology at the Max Planck Institute for Astrophysics in Garching, Germany, since 2012. Earlier he was a professor in the Department of Astronomy and Director of Texas Cosmology Center at the University of Texas at Austin. He obtained his PhD from Tohoku University, Japan, in 2001 followed by postdoctoral fellowship at Princeton University. He is a Fellow of American Physical Society. He has received many awards for his work including Alfred P Sloan Fellow, the Nishinomiya-Yukawa Memorial Prize, the Gruber Cosmology Prize, the Lancelot M Berkeley Prize of the American Astronomical Society, the Chushiro Hayashi Prize of the Astronomical Society of Japan, the Breakthrough Prize in Fundamental Physics, the Inoue Prize for Science and the Nishina Memorial Prize. Prof. Komatsu uses theoretical physics and observational data to study the origin, evolution, and constituents of our Universe. His scientific achievements include the most stringent test of the physics of the very early Universe known as “cosmic inflation”, innovative explorations of dark matter, dark energy and neutrinos in cosmology, and astrophysics of galaxy clusters.