According to the channelled messages from author Dianne Robbins, not only is the earth hollow, but it is also inhabited by advanced civilizations!

Read how this space possesses an inner central sun, with oceans and mountains still in their pristine state. Imagine a perfect garden on a warm summer day, the sunshine only obscured now and then by cool clouds drifting overhead. However, this day does not end, but is continual, since the "sun" (the "central sun" within the heart of the earth) never moves.

This body of light is just the right size and intensity to keep the inner surface at a warm (not cold nor hot) temperature perpetually. Since there is no "night" there, the inhabitants simply take occasional "naps" to replenish their energy. This is the setting just outside the library of "Porthologos," which is a magnificent jeweled structure such as has no equal on the surface of the earth, like a structure out of a living dream. Porthologos is not just a library, but also a holographic "observatory" of our multi-dimensional universe, where all spaces, times, and dimensions may be studied in depth.