Chapter 1: Alternate Universe

The multiverse exists, and when we "time travel," we don't time travel; we go to a universe that is the same as us in every way except for what time it is. This means that it appears as though we are going back in time to the era when Hitler was a baby. The purpose is to prevent World War 2 by eliminating him. However, in that alternate universe, when you come back to your original universe, the events still occurred. This indicates that what happened is fixed and cannot be altered. You might be thinking, "Okay, I'll time travel forward in time in the universe where I killed him." But that approach won't be effective. Time in that universe progresses normally, and you cannot travel forward in time. As I mentioned earlier, you don't "time travel"; instead, you shift to a different universe.

Another option is to bring about changes in the universe you've entered. For instance, I can visit a universe identical to the one I originated from, except in this version, food is free. This suggests that you can modify various aspects of the universe as you desire.