It’s a standard conversation starter at dinner parties everywhere: “What would you do if you had a time machine?” With “kill baby Hitler” being a frequently offered response. Overused as it is, the scenario still raises some moral, ethical, and practical issues. But how, exactly, did this particular baby-killing question become such a time-travel cliche? Vox investigates the strange subject with a new video from Phil Edwards and Christopher Haurbursin. To understand the whole “killing baby Hitler” conundrum, Edwards talks with writer and science historian James Gleick, author of 2016’s Time Travel: A History. It turns out that time travel itself is relatively young as narrative devices go. Shakespeare wasn’t having his characters dart about in history back in the 1500s, for instance. It wasn’t really until H.G. Wells’ The Time Machine was published in 1895 that time travel became a staple of speculative fiction. As Gleick explains, Wells’ novel was an outgrowth of the public’s interest in technology and progress. People of previous centuries didn’t see technological advancement as inevitable.