They finish what they are doing and return to the present, but everything is gone. They reappear in a wild world with no humans, and no signs that they ever existed. They fall to the floor of their platform, the only man-made thing in the whole world, and lament “Why? We didn’t change anything!” ...

The Butterfly Effect is a reference to Chaos Theory where seemingly trivial changes can have huge cascade reactions over long periods of time. Consequently, the Timeline corruption hypothesis states that time paradoxes are an unavoidable consequence of time travel, and even insignificant changes ...

In one story, a paleontologist, with the help of a time travel device, travels back to the Jurassic Period to get photographs of Stegosaurus, Brachiosaurus, Ceratosaurus, and Allosaurus amongst other dinosaurs.

He knows he can’t take samples so he just takes magnificent pictures from the f...

1) Closed Causal Loops, such as the Predestination Paradox and the Bootstrap Paradox, which involve a self-existing time loop in which cause and effect run in a repeating circle, but is also internally consistent with the timeline’s history.

2)

American theoretical physicist Joseph Polchinski proposed a time paradox scenario in which a billiard ball enters a wormhole, and emerges out the other end in the past just in time to collide with its younger version and stop it going into the wormhole in the first place.

Solutions have bee...

There is nothing in Einstein’s theories of relativity to rule out time travel , although the very notion...

Similar to the Grandfather Paradox which paradoxically prevents your birth, the Killing Hitler paradox erases your reason for going back in time to kill him.

Furthermore, while killing Grandpa might have a limited “butterfly effect”, killing Hitler would have wider consequences for everyon...

A self-fulfilling prophecy is only a causality loop when the prophecy is truly known to happen and events in the future cause effects in the past, otherwise the phenomenon is not so much a paradox as a case of cause and effect. 

Say, for instance, an authority figure states that something i...

Scientists have suggested ingenious ways to avoid time travel paradoxes, including

–The Solution: time travel is impossible due to the very paradox it creates

–Self-healing hypothesis: successfully altering events in the past will set off another set ...

For example, if you traveled to the past and killed your grandfather, you would never have been born and would not have been able to travel to the past – a paradox. 

Let’s say you did decide to kill your grandfather because he created a dynasty that ruined the world. You figure if you knock...