For a long time, dark energy, the mysterious force prodding the expansion of the Universe, was considered eternal and unchanging, like yeast that never loses its activity. But explaining such constancy through the laws of the microcosm proved impossible, and scientists began to suspect that the “leaven” might be going flat.
The DESI instrument, a light analyzer of millions of distant galaxies, showed that over the past few billion years, dark energy’s strength has weakened by about 10%. By studying galaxy distributions, astronomers were surprised to find that they are not scattered randomly but arranged in concentric rings, like ripples on water from a thrown stone. This is the frozen echo of sound waves that shook the early Universe.
Now the entire recipe of the cosmic loaf is in question, where dark matter and dark energy were considered immutable ingredients. Cosmologists are trying out new recipes where the dough of space is kneaded with string-like filaments, and dark energy, like live yeast, behaves capriciously: sometimes raging, sometimes quieting down, promising a dramatic finale to the expansion.
By some estimates, dark energy makes up about 68% of all the energy in the Universe.