Is it possible to travel into the past?

In 1895, H. G. Wells published a novel entitled "The Time Machine." This extraordinary futuristic novel appeared a few years before the end of Queen Victoria's 63-year reign, which preceded by only a few years the end of the unchallenged reign of Newtonian physics. Indeed, in 1905, Albert Einstein published his theory of special relativity, which challenged Galileo's conception of space-time. This theory also had the strange feature of predicting a form of travel into the future, no doubt to Wells's great delight! In Galilean space-time, time is the same for everyone, everywhere. In Einstein's theory, however, the durations measured by observers moving relative to each other no longer coincide: time is relative.

Since 1905, true time travel has been achieved, but not with the machine Wells so playfully imagined. The furthest human to travel back in time to date is Sergei Krikalyov: he leaped into the future by 1/48th of a second. This lead over other humans is the result of the 803 days this cosmonaut spent aboard Mir and the ISS (International Space Station). Aboard these space stations, he was traveling at some 27,000 kilometers per hour around the planet. Compared to our clocks on Earth, his own clock, that is, his own time, was less advanced: he aged less than us. In other words, he leaped into the future by 1/48th of a second.

But is it possible to travel into the past?