well you could compare the obelisks to a pivot point, as in the wikipedia.
http://upload.wikimedia.org/wikipedi...e_diagram..png
might sound stupid, but that image may very well represent the field... think about it, we have the ideas of counterweights, and if that image is what were after with the obelisks... well then.. put the two together and you got yourself a lever, something on it probably controled by IR, and it has counter weights..