Time travel is the concept of moving between different points in time in a manner analogous to moving between different points in space, generally using a theoretical invention known as a time machine.
- Chapter 1 — Time Travel Basics
- Chapter 2 — What year is it?
- Chapter 3 — Preventing Paradoxes
- Chapter 4 — Doppelgangers
- Chapter 5 — Returning to the Present
Even if it turns out that time travel is impossible, it is important that we understand why it is impossible. — Stephen Hawking