The Emthruster: Thrust without reaction?

[stevebowers]

Conversion drive became available in 1520 AT, but it was (at first) a transapient technology, and was only mastered by modosophonts later as a form of retroengineered ultratech. Some technologies are within the range of modosophont ability but the transaps got there first. Others are so complex and abstruse that unaided modos might never achieve them by their own efforts.