This article comes from an abridged version written at the Hipparque Cartographer's University.

Faster than light travel via geometry drive is relatively simple and straightforward relative to the theoretical complexity of a four-dimensional translation in space. There are however various elements that the deep space traveller should take into account, be they hurdles or welcomed encounters in the depths of the Milky Way.

A few of these elements are listed below. As usual, the list is not comprehensive.

1 - A Big Star In The Way

One of the most fundamental hardcoded safety features of the geometry drive is that it cannot perform a translation whose endpoint is in solid matter, liquid matter, or high-density gaseous matter. In order to prevent this, the drive "pings" the target destination a millisecond before the jump. If the ping result is negative (no obstacle at endpoint), the jump is performed. Otherwise, the translation is aborted and the drive shuts down temporarily.

Now, one of the main characteristics of space is its emptiness and it is exceedingly rare to find an object large enough to represent an obstacle at an interstellar scale. Given that nebulae are several orders of magnitude not dense enough to register as an obstacle, the closest to an object capable of randomly blocking a translation is a massive star as big as a solar system. A very massive star such as UY Scuti, about 1,700 times bigger than the sun. Even if such stars are but specks of dust compared to the size of interstellar expanses, they can still interrupt careless jumps.

2 - Pulsars

Pulsars are a subset of neutron stars that emit pulses of radiation with incredible regularity. Though astronomers have been using them for centuries to study the interstellar medium, the advent of faster than light travel made pulsars even more interesting. Their regularity and the ease with which pulses can be detected means that pulsars essentially act as a galactic positioning system. They are beacons in the void in uncharted areas. Beacons that can be used to perform long-range jumps with incredible accuracy instead of having to rely on intermediary jumps to correct a course. In fact, pulsars are so useful that the inner regions of the Milky Way with a high concentration of them are known as the "Neutron Pathway" due to the way they provide a safe environment of well-charted reference points.

3 - Red Dwarf Regions

Red Dwarfs are very common in the Milky Way, accounting for about 85% of known stars. In general, they aren't really liked by stellar navigators for a simple reason: for a translation to be cost-effective it is paramount to assess the correct distance between the entry point and the exit point. The more accurate the estimated distance, the fewer "correction jumps" will be needed.

In charted space, distances between stars are well-known and updated constantly. In uncharted space it's a different story - even with modern technology assessing the correct position of a star at interstellar scale is quite hard. This task becomes even harder in regions that are devoid of bright, hot stars that can be used as points of reference. Red dwarf rich "cold zones" are thus often considered as a real bane for navigators.

4 - Black Holes

It is uncertain how high-mass objects interfere with geometry drives given that neutron stars do not seem to really hamper translations - however, no commander would be stupid enough to translate too close to a singularity. Whether it's due to their mass or another unknown factor, black holes are not very friendly to geometry drives. They are known to "stagger" translations when they find themselves in the close vicinity of the exit point. In other words: translation is still possible but the accuracy is completely random. Strangely enough, the effect is stronger near small stellar black holes than supermassive ones. It doesn't change the fact that black holes should be avoided by navigators.

5 - Artificial structures

When Inyanga-class exploration ship Hedi Lamarr stumbled across a system it couldn't translate towards, it was believed to be some kind of technical oddity. When it happened to a second ship and a second system, the Starmoth Initiative started to suspect something else was in play. When the same phenomenon was reported by other polities with vastly different ships it became clear that these systems had something very peculiar in them.

And indeed they did. Their spectrum was completely unusual, to a point there was only one way to explain it: the presence of an artificial structure surrounding the main star, diffracting its light and altering its spectrum. An artificial construction capable of intercepting faster than light translations, interacting with the very structure of spacetime. Seen from afar they looked like gigantic, hollow eyes in the void.

None of these star systems has been explored. The sublight ships still haven't arrived.