The expansion of the universe is a phenomenon that can only really be measured by observing T galaxies separated by massive gulfs of space. The further apart they are, the faster they race away from each other. And that effect is speeding up. Dark energy is the name given to the hypothetical force that is causing this acceleration. Think of it as gravity’s counterpart, providing a negative pressure that fills the universe and drives objects apart at an increasingly rapid rate. But dark energy doesn’t seem to work on objects as gravity does. It preys on the very fabric of the cosmos itself – expanding the very space between objects.

Despite the fact it accounts for roughly 68 per cent of the universe’s total energy, we know very little about this mysterious repulsive energy. We aren’t completely in the dark about dark energy’s ‘secret identity’, however. Cosmologists are aware of a number of ‘prime suspects’ that could account for its effects. “The leading candidate is the cosmological constant, or lambda, which we associate with the vacuum of space’s energy,” Luz Ángela García, a physicist at Universidad ECCI in Bogotá, Colombia, explains. “Other possible candidates are quintessence fields, proposed in the early 21st century to establish a