The Universe is expanding faster and faster. We used to chalk that up to dark energy — a mysterious force working alone. But the latest measurements seem to have eavesdropped on a private conversation: it appears dark energy is not silent but whispering back and forth with dark matter.

By comparing how galaxies flew apart in different epochs, scientists realized: models where dark matter and energy exchange signals explain the data just as well as the idea of a capricious dark energy. There was no need to invent new particles. It’s enough to acknowledge: the two dark riddles are having a dialogue.

If that's the case, their 'conversation' leaves a trace. Future sky maps — for example, from the Euclid telescope — will be able to see this whisper in the way galaxy clusters bunch together. It’s as if the cosmos leaves writings we are only beginning to read.