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.
2022
2014
2011
2001
2019
2024
2020
2015
1929
1931
2023
1932
2021
1918
1972
