Years ago I read a novel I only vaguely recall. The central premise was that a scientist was studying some class of matter which does not interact with our baryonic matter, much if at all. During his research he discovers that there is a whole universe of this ghost matter, and in fact a planet of it coexisting within Earth. This planet gets tugged out of its orbit (I think by some large passing 'ghost world' body) and there is a whole sequence describing the scientist, who has since learned to see into this world, watching as 'people' and structures rise and fall out of our world due to the rotation of the ghost world. I seem to remember that he eventually figures out how to communicate with them, and maybe even interact physically? That's all I can recall, but I'd really like to recover that book. Any notions?