I've just finished reading the book "Time Traveler - A scientist's personal mission to make time travel a reality", by Dr. Ronald L. Mallett, professor of physics at the University of Connecticut. In this book Mallett explains a new theory to travel back in time using a laser ring, which creates frame dragging and closed loops in time, according with the Einstein's gravitational field equations. Did anyone of you read this book, too??? Or does someone know something more about this theory, and what do you think of it??? And....another thing...Don't you think travelling back to the past would go against the law of thermodynamic, especially the law of entropy??? What do you think...???