Just because it didn't happen here doesn't mean that it never happened.These are memoirs of Harry Black, the founder of Harry's Time Tours. This tells of the early years, when Harry was first transported to this world and met his beautiful sidekick and wife, Mary. The Many Worlds Interpretation was amended by Brendan Devlin, so now there are many worlds instead of an infinity, and it is possible to communicate from one world to another, and Harry is living proof of that. In the world that Harry is from time travel is not just possible, but it is a common way to have a vacation, and it is an excellent tool for researching history and anthropology. If you have a question about the past, then Harry can help you. Have you ever wanted to spend an evening with Cleopatra or watch the defeat of Troy? Harry can provide transport to any time and place in the history of humanity, and if you don't know exactly when, he can do the research to find the time and place that something happened. If your interest is criminal, then he might still be interested.But keep in mind that anything that you change in the past may create a new space-time, and it won't alter the history of this world. So kill Hitler in 1923, if you want, but it won't change what happens in this world. Be careful with the future. The Really Great Pandemic is up there, and it is incurable, and the mortality rate is high. On the other hand, the virus inserts a bit of DNA that keeps telomeres from deteriorating with all that implies.