What do your phone, the night sky, and the Big Bang have in common? They all involve light, in one form or another. In this talk, we will follow light across the Universe and back in time, towards the Big Bang. We begin with EMF in everyday life - the electromagnetic waves around us - then move out to the light we receive from stars and galaxies, and finally reach the Cosmic Microwave Background - the oldest light we can see, an afterglow from the early Universe. This ancient signal shows us what the cosmos was like nearly 14 billion years ago, and it also points to one of the biggest mysteries in modern science: most of the matter in the Universe is dark - invisible to us - and we still do not know what it is. Without dark matter, there would be no galaxies, no stars, and no us. To uncover these hidden pieces, physicists use CERN's Large Hadron Collider to smash particles together and recreate the extreme conditions of the early Universe. From the EMF around us to the Big Bang, this is a story about light, matter, and our search for the dark, hidden pieces that dominate the Universe.