Instruct: Classify Amazon reviews into positive or negative sentiment
Query: An introduction to 4D space.

This is a nice well-written book about what a 4D Universe would be like, and delves a bit into Einsteinian spacetime. The problem with this book is that Rucker wrote another book "Geometry, Relativity, and the 4TH dimension" which has tons more information in it and is at least 1/10th the size of this book. So, in a way, this is just a wordy repeat of his older book.