“I’m pretty sure that if no physicist had ever existed, I would still be here.
In fact... I am here despite those physicist who have created weapons of such mass destruction “
Those events changed history. If you were born after 1945 you owe your existence to that altered history.
And if a caveman stepped on a certain butterfly that would’ve changed history too... The what ifs are enormous... But time travel never happened and never will... If it did, we would know it by now.