A very well crafted and researched scifi novel. The author skips back and forth from modern day to the dark age Germany, socio-anthropology and multidimensional physics, and ties it all together with a masterful touch.
Eifelheim is remarkable not only for the hard science it brings to science fiction, but its imaginative grasshopper type aliens, and the author's incredibly detailed knowledge of Germany's Black Forest in the Middle Ages. I've never read science fiction that was so well-grounded in historical fiction. What a delight.