Is time travel allowed: The Chronology Protection Conjecture

Time travel has long been a dream of scientists and story tellers alike, but does the universe protect itself from time travel. If time travel is possible then it throws up the possibility of some strange and unwanted paradoxes such as the Grandfather paradox and the bootstrap paradox. In the 1990s Stephen Hawking postulated the idea that the universe protects itself from time travel in something he called the Chronology Protection Conjecture. In this video we look at this and other protective measures that the universe might have against the actions of wayward time travellers.

Picture Credits
Sheep by Uschi_Du
https://pixabay.com/photos/sheep-sheepshead-sheep-portrait-4673941/
Valentina Tereshkova
RIA Novosti archive, image #612748 / Alexander Mokletsov / CC-BY-SA 3.0 / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)
Time Machine
Published by Heinemann in 1895 / Public domain
Andromeda Galaxy
Adam Evans / CC BY (https://creativecommons.org/licenses/by/2.0)
Eruption of Vesuvius
Tim Evanson from Cleveland Heights, Ohio, USA / CC BY-SA (https://creativecommons.org/licenses/by-sa/2.0)
Great fire of London
Museum of London / Public domain
Battle of Culloden
David Morier (1705-1770) / Public domain