Dark energy just opened a can of wormholes. An extension of Einstein's gravity may explain this strange force and give us stable wormholes to navigate quickly through the cosmos – but there is a catch.

Building one of these cosmic shortcutsMovie Camera would require talking with aliens made of exotic matter, who can only send us messages via space-time ripples called gravitational waves.

The universe is expanding at ever-increasing speeds, and the prevailing theory is that a mysterious force called dark energyMovie Camera is driving it. But Manuel Hohmann at the University of Tartu in Estonia has been working on an alternative called multimetric gravity, which involves copies of the standard model of particle physics that each have slightly different properties.

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