It is called the Time Traveler's Paradox. In which a scientist creates a Time Machine and kills their younger self. So now a man who should not- can not- exist, somehow does. That is the Paradox, and Paradoxes are impossible.
2019
2013
2018
2022
2014
2021
2003
2015
2024
1933
2023
2017
1932
2020