Glider

A glider is a structure used by civilizations to travel between universes through interuniversal space. It takes the form of a wavepacket that is capable of travelling in the interuniversal medium by making use of disturbances in the field, created from within a universe.

Upon colliding with another universe, it creates a disturbance in the target. The shape of this disturbance can be incredibly complicated, and depends on the shape of the glider, which is determined when the glider is created but can also evolve as it travels. The very earliest gliders simply signal existing civilisations in the target universe; more sophisticated gliders can assemble nanofabricators out of dust and load them with a copy of the sender's values, as well as perform computations en-route.