Instruct: Classify Amazon reviews into positive or negative sentiment
Query: An interesting book

If you would like to find a book that talk about time machine and related concepts (the possibility of going back to the past, going to the future, the implied logical paradox, etc), don't miss this book. The author manage to convey complex concepts to the reader with simple languages. I like Stephen Hawking's history of time but it is too difficult for me. Paul Davies's book is small in size, I manage to "finish" and "understand" it within one day.