Will we ever be able to travel back in time?

Theoretically, yes

Einstein’s theory of general relativity has some solutions that are sufficiently twisted so as to allow time travel to the past, such as wormholes and moving cosmic strings. Just as Magellan’s crew went west around the world and arrived back in Europe, a time traveller can go towards the future and circle back through curved space-time to visit their past. If you built a time machine in 3000 by twisting space-time, you could go from 3002 to 3001, but you couldn’t go back to 2016 as that was before it was built.

To know whether these machines could be created, we’ll need to learn the laws of quantum gravity – how gravity behaves on microscopic scales. It’s why physicists find the possibilities of time travel so interesting.

Professor J. Richard Gott, Princeton University, New Jersey