Galaxies are like giant kitchens where, in stellar cores, light atoms are fused into heavy ones — much like flour and water becoming bread. When a star dies, it spills its accumulated riches into the interstellar gas, seasoning it with 'spices': oxygen, carbon, iron. The James Webb Telescope caught the faint glow of heated oxygen in 34 galaxies shining 3 billion years after the Big Bang. By measuring the brightness of this light, like gauging a flame's temperature, astronomers calculated the oxygen abundance — breaking light into its colors works more precisely than a kitchen thermometer here.

It turned out: the heavier the galaxy, the more oxygen it holds — a relationship nearly identical to that of today's nearby galaxies. But computer simulations of the universe's evolution couldn't reproduce this consistency. Back in the era of cosmic expansion 10 billion years ago, stars were born much faster, yet the recipe for metal enrichment never wavered — as if a chef cooking ten times faster never missed a gram of seasoning.