nope

edit:

there are energy patterns at the poles that lead to reports of strange lands or hollow earth... when people end up in places beyond the known globe, it is because they have travelled to another reality through these energy vortices.

i believe the firmament to refer to an effect that keeps certain beings from straying too far from earth. there are up to three different effects i know of that this could be. it could be the van allen radiation belt. i'm not really sure. but i'm fairly certain its not a reverse fish-bowl, simpsons type deal.

our adversary on this planet has wanted to escape for a long time. if you ask m tsarion, john dee used enochian magic tto make a deal with 'macrobes', inhuman beings on another plane of existence altogether. john dee asked them how to escape. the macrobes said sure, and gave them a set of instructions. in return, the macrobes asked for blood. lots of it. this is why wars are fought in specific locations by men wearing occult symbols, with both sides funded by the same hidden hand.

and yeah. yes to extensive cave systems. yes to DUMBs. but no to hollow earth, unless you find a way to travel to a reality where that is true. but that earth is not this earth.

nope