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.
2024
2016
2013
1928
2012
1948
1947
2019
2007
2009
2010
1989
2018
2021