The Grandfather Paradox

"Will time travel ever be possible?" is one of the controversial questions/topics which has prevailed on man's mind from over a century ago. The grandfather Paradox argues that travelling back in time is impossible, however it does not state it is impossible to travel to a future time period. In 1943, Rene Barjavel, who was a French journalist and science fiction writer spent a lot of time thinking about the possibility of time travel,  and came up with this theory. In his book Le Voyageur Imprudent the main argument presented  was imagine that you build a time machine. It is possible for you to travel back in time, meet your grandfather before he produces any children (i.e. your father/mother) and kill him. Thus, you would not have been born and the time machine would not have been built, therefore, a paradox. One of your parents would not have been born so therefore you would never had existed. Another time travel paradox is Robert Heinlein's classic short story All You Zombies. Doesn't Time travel defy the laws of physics? In the space of matter and time how could it be possible? This theory has several gaps in it, but it could be accurate, maybe. There is no evidence that time travel is or isn't possible, but why should we try to alter what is meant to be or rather change what helped to shape and influence our present and future? Couldn't that have serious consequences?
https://www.youtube.com/watch?v=Y6RjjaEy59I

References:

http://abyss.uoregon.edu/~js/glossary/grandfather_paradox.html

http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Grandfather_paradox.html