You don't want to mess this one up. It's the philosophical question that keeps cropping up - if you could travel back in time, would you kill baby Hitler? Okay, let's be honest, the first thing you'd do is go and see the dinosaurs, but would killing one of history's worst babies be the second thing? Of course, at first glance, there's no right answer to the question. If you say yes, you'll have stopped one of the worst periods of human history from occurring, but what would the effects of changing the course of history be? Maybe things will turn out worse? And if you say no, well, you could have stopped one of the worst periods in human history, and you didn't. As the Vox video above explains, the question of travelling back in time to change the past really came to the fore in 1895, when H. G. Wells published his novel, The Time Machine, it was one of the first times that the phrase "time travel" really hit the public consciousness. It was a real sign of the times - back in the 1600s