The universe is full of invisible stuff. Dark matter serves as an unseen scaffold: without it, galaxies would fly apart (proven by Vera Rubin). Dark energy is a mysterious force that pushes the world apart faster and faster. Together, they resemble a bicycle: dark energy is the invisible rider, dark matter is the wheels, and it seems the rider sometimes pedals. But the big mystery is why two ways of measuring this expansion give different numbers. The glow of the cosmic microwave background (the afterglow of the Big Bang) and distant star explosions observed by Adam Riess show conflicting speeds. This is the Hubble tension — a crack in the theory.

To check whether dark energy feeds matter, they used gravitational lenses: galaxy clusters bend light like giant magnifying glasses. From the distortions, they reconstructed the amount of dark matter in 143 such lenses and in the famous cluster Abell 1689, imaged by the Hubble telescope. Computer simulations factoring in redshift (the stretching of light from receding objects) peered into the past.

This caused the expansion of the universe to accelerate not halfway through its age, but almost three times earlier. Such a shift smooths out the discrepancy in measurements and changes the whole picture of cosmic evolution, challenging the model laid down by Einstein.