Instruct: Classify Amazon reviews into positive or negative sentiment
Query: It's beyond science, beyond time, and beyond imagination.

This is not a "time travel" episode. One man ( Clay ) awakens so far into the future there are no similarities between now, and the Earth-time he finds himself in. The book holds the readers mind and feeds it with details of all the senses. Within the story are several mini adventures, each having it's own mind bending concepts. There is some sexual content, so the book is not for young kids. I've read it three times over the last ten years, and will read it again in a few more. This is the one that hooked me on Silverberg.