Imagine you’ve been studying the history of warfare in the 20th century. Then you travel back in time to 1939 and tell someone how the Nazis could win World War II. Suppose your information is overheard by someone else who becomes a Nazi general and uses it to actually win World War II for the Nazis. Suppose further that your mother dies as a result of the Nazi victory before giving birth to you. Well, if you are never born then you could never have traveled back in time to give away the information that causes you not to be born. Here we have another version of the time travel paradox.