A hundred years ago Einstein cooked up the recipe for gravity, and Lemaître noticed that the kitchen itself – the Universe – is expanding. Today we know: the expansion is accelerating, as if a mysterious broth is being added to the soup – dark energy, which makes up 70% of the menu, but its recipe is lost.

To check whether Einstein could be tweaked, an algorithm acting like evolution took charge: machine learning bred thousands of equations, crossed them, and kept those that passed the data test. As feed, it used supernovae and measurements of sound waves from the early Universe from the DESI survey. By the redshift of their light – the stretching of radiation as it flies through expanding space – the expansion rate was computed for different epochs. Each version was crunched through a numerical simulation of the cosmos. The verdict is strict: any viable variant is indistinguishable from the standard one. Like mustard in a dessert, the slightest liberty with gravity immediately spoils the whole dish.