The Universe’s first magnetic fields were shockingly weak, but changed everything

Early universe magnetic fields were surprisingly weak—comparable to brain neuron magnetism but billions of times weaker than fridge magnets—yet they left lasting traces throughout the cosmic web. Scientists at SISSA and partner universities used 250,000 computer simulations to establish that these weak fields (about 0.2 nano-gauss) actually helped accelerate star and galaxy formation, setting a new upper limit that's significantly lower than previous estimates.