Phantom Zone

The Phantom Zone is an alternate dimension first discovered by Kryptonian scientist Jor-El. After Jor-El created devices which could create passage into the Phantom Zone, the dimension was used by the Kryptonian council as a "humane" form of imprisonment.

A barren wasteland, inhabitants of the Phantom Zone reside in a ghost-like state of existence from which they can observe their original plane of existence but cannot physically interact with it. As a side effect, inhabitants do not age or require sustenance in the Phantom Zone and, posses the ability to develop telepathic abilities that can be used to affect their original plane of existence.

Previously, criminals were punished by being sealed into capsules and rocketed into orbit in suspended animation with Sunstone Crystals attached to their foreheads to slowly erase their criminal tendencies. Following the dimension's discovery the method was abolished in favor of the Phantom Zone, which was considered to be more humane and cost-efficient.

Trivia

 * The Phantom Zone first appeared in Adventure Comics #283 (April, 1961)
 * The Phantom Zone has been independently discovered by the Bgztlians, the White Martians, and the villains Loophole, Prometheus, and the first Queen Bee; who call it the "Buffer Zone", the "Still Zone", the "Stasis Zone", the "Ghost Zone", and the "Honeycomb", respectively.