In general, perpendicularities are created by the presence of a Shard on a world. The concentration of so much Investiture in the Cognitive and Physical Realms creates points of ... friction, where a kind of tunneling exists. At these points, Physical matter, Cognitive thought and Spiritual essence become one - and a being can slide between Realms.
The existence of a perpendicularity (which often take the form of pools of concentrated power in the Physical Realm) on a world is a hallmark of a Shard's presence. According to Khriss, this is what makes First of the Sun so interesting ... because there isn't a Shard in the world's system.
Perpendicularities are used by Worldhoppers such as Khriss and Hoid to travel between worlds. They are formed through the concentration of Investiture in the Physical and Cognitive Realms. As a result, most are commonly found at Shardpools.
First of the SunEdit
The pool below the Pits of Hathsin on Scadrial was the main perpendicularity before it was destroyed by Kelsier. The other known perpendicularity, the Well of Ascension, was extremely dangerous during the imprisonment of Ruin.
Properties of PerpendicularitiesEdit
According to Ivory, there is only a stable junction between Shadesmar and the Physical Realm when somewhat of a person remains within the Physical Realm at the time:
|“||"Only when a piece of you is there," Ivory said. "Today, that is not. You are here, Jasnah. I am ... sorry."||”|
–Ivory to Jasnah