The Andromeda-Milky Way collision is a predicted galaxy collision that is due to take place in approximately 3 billion years’ time between the two largest galaxies in the Local Group – the Milky Way and the Andromeda Galaxy.
Central to Alastair Reynolds’ science fiction books in the Revelation Space universe, the Andromeda-Milky Way collision is set to occur in about 3 billion years. A machine race named the Inhibitors, that stems from organic quadrupeds, have designated themselves the shepherds of the galaxy and are culling any spacefaring civilisation in order to minimize the effect of the collision. They are moving star systems around, but they are also suffering from enthropy. The Dawn War happened millions of years ago and the Inhibitors have decided on a form of post-intelligence as non-sapients, meaning that they aren’t aware, and wholly machine.
They possess advanced technology with is partly based on femtotechnology or structured space-time and are Von Neumann machines, capable of self-replication. By confining intelligent life to just a few systems, the Inhibitors make moving solar systems around a far easier and more centralized task.
It is likely that the two galaxies will merge and the resulting galaxy will be called Milkomeda. Andromeda is believed to have collided with another galaxy in the past. Such events are quite common on the galactic scale.