The magnetic fields that formed in the very early stages of the Universe, may have been billions of times weaker than a small fridge magnet, with strengths comparable to magnetism generated by neurons in the human brain. Yet, despite such weakness, quantifiable traces of their existence still remain in the cosmic web, the visible cosmic structures connected throughout the Universe.
These conclusions emerge from a study using around a quarter of a million computer simulations, conducted by a team from SISSA-Scuola Internazionale Superiore di Studi Avanzati in collaboration with the Universities of Hertfordshire, Cambridge, Nottingham, Stanford, and Potsdam. Observational data were subsequently used to validate these findings. The research, recently published in Physical Review Letters, specifies both possible and maximum values for the strengths of primordial magnetic fields. It also offers the possibility of refining our knowledge of the early Universe and the formation of the first stars and galaxies.