An o-region was an area of space that was so far out and isolated that its light took a long time to reach the rest of the universe. The Eighth Doctor said that an o-region was similar to a mini universe. The release of slow light from an o-region in a cave in Siberia caused George Williamson to become insubstantial, but also able to travel through time by walking. The fire elemental was created when an explosion caused more energy to escape from the same o-region. (PROSE: Time Zero)

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