http://cp3.irmp.ucl.ac.be:80/PAI PhTh-FI-ULB Calendar - Week of 4/12/2026 http://cp3.irmp.ucl.ac.be:80/PAI/day.php?getdate=20260415&cal=PhTh-FI-ULB Wed Apr 15 2026 12:15 PM: http://cp3.irmp.ucl.ac.be:80/PAI/day.php?getdate=20260416&cal=PhTh-FI-ULB Thu Apr 16 2026 11:00 AM: Unifying the Higgs Mass Hierarchy, the Cosmological Constant, and the Axion Quality Puzzles http://cp3.irmp.ucl.ac.be:80/PAI/day.php?getdate=20260417&cal=PhTh-FI-ULB Fri Apr 17 2026 11:00 AM: <b>The emergence of galaxies in the first billion years</b><br><br>Galaxy formation in the first billion years marks a time of great upheaval in our cosmic history: the first sources of light in the Universe, these galaxies ended the 'cosmic dark ages' and produced the first photons that could break apart the hydrogen atoms suffusing all of space starting the process of 'cosmic reionization'. The past few years have seen cutting-edge instruments such as the James Webb Space Telescope (JWST) provide tantalising glimpses of such galaxies assembling in an infant Universe. Puzzlingly, these observations are also yielding a sample of unexpectedly numerous and large black holes (up to a 100 million solar masses) within the first 600 million years, posing an enormous challenge for galaxy formation models. I will show how this data is providing an unprecedented opportunity to pin down the reionization state of the Universe in addition to providing an unrivalled resource for understanding the reioni