The Senova Cabal
There are two major unexplained phenomena evident in the Pact Worlds and nearby.
The Drift engine is – supposedly – a literal godsend (having been designed by Triune), allowing quick and easy jumps within a solar system in hours, and travel anywhere within the galaxy in under a month. It works by traveling through the Drift – a plane of existence unlike any other, where travel routes are untethered from their locations on the Material Plane.
There's just one problem – it's all bullshit.
If the Drift was another plane, then someone could plane shift onto it. No one can. If the Drift was untethered to the Material Plane, then travel could be instantaneous, or nearly so – but it isn't.
To make matters worse, the Drift engine simultaneously violates nearly every law of both physics and magic. It takes more energy to create a portal to an adjacent town than it does to power a Drift engine throwing you to the other side of the galaxy. It takes no magical skill to build a Drift engine (although it requires some very precise machining), but no amount of nonmagical technology has yet succeeded in breaching the planar barrier to any other plane. The Drift engine cannot be engaged too close to a planet, but coming out near (or even on) a planet is possible, if incredibly dangerous.
The Gap is a period of an unknown number of years, during which space travel was perfected and the planet of Golarion vanished, save for the Starstone of Absalom. The problem is, no one quite knows what happened during that time. How is it possible to remove a planet and what had to be at least a century of memories from every person in the galaxy without leaving a trace? Yet this is what happened.
Surely the two are unconnected – except the only surviving piece of Golarion, the Starstone, attracts Drift travelers. There are hundreds of wild conspiracy theories in the Pact Worlds on why that might be.
The monstrous truth would eclipse them all, if it were known.