Once yet again it is not a possibility ever. Not in the year 3300 or even farther ahead it will never happen.
Time is a constant NOT a variable therefore it goes only one direction. The past is set in stone, titanium, forever it will not change in any way. Even a visit to the past would leave some effect of you being there.
Step on a bug, pick a flower, find money on the ground, buy something, you will destroy the future that those things were connected to in every way.
Go back in time to kill Hitler, ok we all want to do that but, everyone at the instant would forget who he ever was, families would not be destroyed so current families that were created because of Hitler would never exist.
So if the person who developed time travel was a descendant of a holocaust survivor and someone went back and killed hitler. The inventor would never have been born, so how did you go back in time to kill him? Most likely even in the U.S. families were changed due to him so you might not have been born either.( Or any country related to that war in speaking, millions of people were affected by this.)
Physics, yeah I study them quite often still even at my age, mostly advanced Quantum physics and theory of relativity.
Just like the American Government has a secret police force watching those that spy on the White House, Roswell and NORAD, and kill them if they find ANYTHING, including the wife and children of the "spy" There also is a body of people out there listening and watching for someone to try and break the fabric of time and they also will oddly disappear, as well as wives and children. There are things in this world humans are not meant to touch and mess with and this is one of them. Thank goodness there is no way to actually ever do it though, unless with cameras and a movie studio. (Or with a DeLorean)