Time Machines: Time Travel in Physics, Metaphysics and Science Fiction by Paul J. Nahin
A lively study of how time travel has been portrayed in fiction from the 18th century to the present. The author also discusses how modern physicists are now giving serious attention to what was once dismissed as sheer fantasy. Technical appendices, using only first college calculus, are supplied for those with a mathematical bent. This book is intended for general science readers.