Gap

Possibly distantly related to the Ginnungagap, this is the unexpected discontinuity a Stepper will encounter after a million or so Long Earths. Many an unwary stepper has come to grief here, expecting to find a new Earth under their feet only to suddenly project themself into the inky cold and airless void of deep space. Those who are quick on their feet can get away with it and step back. Others... well, it is speculated their bodies, or parts thereof, will float through space until attracted by the gravitational pull of the nearest planet, sometimes the Long Venus but more usually the Long Mars. Bacteria present in the human gut, deep-frozen in space and cushioned from burn-up on atmospheric re-entry, are blamed for kicking off the evolutionary cycle on Joker Mars. this leads to the incredibly things seen by Frank Wood, Sally Linsay, and Willis Linsay, as they step through the infinity of the long Mars in adapted aircraft.

The Gap has also been responsible for causing near-fatal damage to the original Mark Twain airship, which found it an unwelcome surprise. forewarned, all later twains have been built with exposure to deep space in mind.