Bootstrap Paradox
The Bootstrap Paradox is a theoretical paradox of time travel that occurs when an object or piece of information sent back in time becomes trapped within an infinite cause-effect loop in which the item no longer has a discernible point of origin, and is said to be “uncaused” or “self-created”.
A time traveller who was a big fan of Beethoven goes back in time to 18th century Germany to search for Beethoven for an autograph. Upon reaching the destination, the time traveller cannot find Beethoven anywhere, not even Beethoven's family have heard of him. Not being able to bear the thought of a world without Beethoven's music, the time traveller coincidently has all of Beethoven's sheet music, he copies it up and publishes it. The time traveller has become Beethoven and the timeline resumes as usual, this is what we call a Bootstrap Paradox.