1. Time travel & paradox

2. A paradox is a logical contradiction
An example is "This statement is false“.
Can an omnipotent being create a rock too heavy for itself to lift?
"It's raining, but I don't believe that it is.“
In seeking happiness, one does not find happiness.
Increasing road capacity at the expense of investments in public transport can make overall congestion on the road worse.

3. A father and his son are driving down the road
A father and his son are driving down the road. The car crashes into a tree and the father is killed. The boy is rushed to the nearest hospital where he is prepared for emergency surgery. On entering the surgery suite, the surgeon says, "I can't operate on this boy. He's my son."

4. The apparent paradox is caused by a hasty generalization, for if the surgeon is the boy's father, the statement cannot be true. The paradox is resolved if it is revealed that the surgeon is a woman — the boy's mother.

5. Paradoxes are unavoidable in time travel
The grandfather paradox would arise if a time traveller were to kill his own grandfather before his mother or father had been conceived, thereby preventing his own birth. This is a specific example of the more general observation that a time-traveller's interaction with the past — however slight — would entail making changes that would, in turn, change the future in which the time-travel was yet to occur, and would thus change the circumstances of the time-travel itself.

6. Bootstrap paradox
Can a time traveler send himself information with no outside source?
After information or an object is sent back in time, it is recovered in the present and becomes the very object/information that was initially brought back in time in the first place.
Robert Heinlein’s "All You Zombies" chronicles a young man (later revealed to be intersex) taken back in time and tricked into impregnating his younger, female self (before he underwent a sex change); he thus turns out to be the offspring of that union, with the paradoxical result that he is his own mother and father. As the story unfolds, all the major characters are revealed to be the same person, at different stages of her/his life.

7. Predestination paradox:
A man travels back in time to discover the cause of a famous fire. While in the building where the fire started, he accidentally knocks over a kerosene lantern and causes a fire, the same fire that would inspire him, years later, to travel back in time. The bootstrap paradox is closely tied to this, in which, as a result of time travel, information or objects appear to have no beginning.

8. Temporal paradox:
What happens when a time traveler does things in the past that prevent him from doing them in the first place?
Grandfather paradox: You travel back in time and kill your grandfather before he conceives one of your parents, which precludes your own conception and, therefore, you couldn't go back in time and kill your grandfather.
Hitler's murder paradox: You travel back in time and kill a famous person in history before they become famous; but if the person had never been famous then he could not have been targeted as a famous person.

9. Predestination paradox
If everything exists in time exactly laid out, then how do we appear to have free will ?