A weird theoretical cousin of the Higgs boson, one that inspired the decades-long hunt for the elusive particle, has been properly observed for the first time. The discovery bookends one of the most exciting eras in modern physics.

The Higgs field, which gives rise to its namesake boson, is credited with giving other particles mass by slowing their movement through the vacuum of space. First proposed in the 1960s, the particle finally appeared at the Large Hadron Collider at CERN near Geneva, Switzerland, in 2012, and some of the theorists behind it received the 2013 Nobel prize in physics.

But the idea was actually borrowed from the behaviour of photons in superconductors, metals that, when cooled to very low temperatures, allow electrons to move without resistance.

Near zero degrees kelvin, vibrations are set up in the superconducting material that slow down pairs of photons travelling through, making light act as though it has a mass.

This effect is closely linked to the idea of the Higgs – "the mother of it actually," says Raymond Volkas at the University of Melbourne in Australia.

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