The year is 2807 A.C.E. Humanity has spread to the stars, and maintains an interstellar empire 10,000 light years in radius in the Milky Way. Long ago, humans discovered basic single-cell life in other places in the Solar System and Galaxy. This indicated that intelligent life was not special to Earth, and raised the weight of the question as to why we had not detected it yet.
Decades ago, a mission was launched: it would be man's first expedition to another galaxy. Conventional travel via sub-light speed antimatter rockets could not reach another galaxy in a reasonable amount of time. The faster-than-light drives that Humanity uses are also not capable of warping intergalactic distances. The solution was the creation of a gate. By this time, Humans had a bearing on wormholes, with the ability to create a wormhole pair and keep it from collapsing. Unfortunately, the pair could only be created locally, and therefore each side of the wormhole was within a few meters of the other unless moved apart.
They created a pair of wormholes in a geostationary orbit of Earth, and assembled a ship around one of them. This ship would contain the wormhole, and was able to move it out of orbit of the Earth. It was fueled with the largest antimatter reserves Humans had to offer, and used a warp drive in addition to antimatter engines to reach its destination.
Earlier this year, 2807, it arrived at an outer arm of the Andromeda galaxy. In an effort to incentivize exploration and colonization of the new territory, the Empire will be opening the wormhole in Earth orbit to the public in a massive event called the Reaching. It will be the first mass-expedition and exploration event in human history.