Killing Hitler Early
It’s the most popular proposed use for time travel, and it’s also one of the worst.
Anyone with a fairly basic understanding of physics (and its too-cool brother, meta-physics) gets why time travel is inherently paradoxical, i.e. impossible by our human understanding of logic and mathematics. But as Planck, Heisenburg and even Einstein himself have proven, physics don’t always obey the letter of logic and mathematics.
So we’re left with the infinitesimal, but still real possibility that someone might invent a time machine, and thinking themselves particularly altruistic, go back to the mid-1920s and kill a middle-aged rejected art student named Adolf Hitler. Sounds great, right? World War II is averted, six million Jews, gypsies, homosexuals and cripples go about their daily business, and history is irrevocably improved. No obvious problems there, surely?
Well, exactly how bad idea Killing Hitler Early (KHE) is depends on what interpretation of time travel you adhere to.
If, like Stephen Hawking, you believe that time is one-way and deterministic, you simply won’t be able to KHE. Your coming and failing has already happened, and history will be unaffected by your actions. You’ll probably be killed by a Berlin mugger or something before you can get to Mein Fuhrer. So while this theory is depressing for the whole ‘free will’ theory, at least your impact on history will be marginal.
The Divergent Choice theory is the opposite of this – it believes very much in free will. Basically, it states that if you go back in time, people may very well make entirely different choices even without your input. Hitler might decide not to invade the Soviet Union, that waiter might soak his balls in your soup, and Karl Marx might have taken up a lucrative career as a painter. Everything could and would be different, as all these choices collide and interact. As such, going back to change things is pointless – the second time around, history would go totally differently regardless of what you did. By killing Hitler, you would be certain of changing nothing, and you’d probably have murdered a man who hasn’t and wouldn’t do anything particularly evil. But again, the Divergent Choice theory just makes you a dickhead – it doesn’t make you Galactus, Eater of Worlds.
But the two other primary theories of time travel make KHE extremely problematic. Those are, by their highly informal names, the Many Worlds Theory and the Reset Button Theory.
The Many Worlds theory holds that when you head backwards in time, you are effectively creating a new timeline, distinct and independent from the original. Thus, time travellers aren’t actually changing their history – they’re creating a new one for them to live in. And of course, they can never return to their own history.
The Reset Button theory is the exact opposite. When going back in time, you absolutely do not create a new timeline – you destroy your own, literally rebooting it from an earlier point. When you travel from 2012 back to 1920, you are obliterating everything and everyone from 1920 onwards, and starting again.
In both situations, the problem with KHE is the same. You (and you alone) definably change history. By the Many Worlds theory, the original history is still out there somewhere, and by Reset Button it’s not, but that’s the only difference. You are still reshaping the 20th century onwards by KHE.
And that is a massive problem.
This is the part where I start to sound dispassionate; callous, even. I’m sorry for that, but please remember that we are talking about travelling back in time to kill Hitler. Permit me a bit of a distant, cerebral perspective.
The trouble with KHE is that World War II was the foundation point of, almost literally, every major historical even that followed. I assume you’ve heard of the Butterfly Effect? Well, this is the Pterodactyl Effect. No, forget that, this is the Fleet of a Million 747s Effect. Regardless of how competent the man was, Hitler had a massive impact on the course of World War II. The invasion of the Soviet Union was his brainchild. His fingers were in every tactical and strategic pie. The vast majority of the Holocaust was under his direct orders. A convincing case could be made that without Hitler, the National Socialist Party would never have ruled Germany. And if you take that away… World War II, and everything that follows, becomes completely unpredictable.
Without a Europe-spanning war, would Japan have had the guts to snatch up British and US territories, let alone directly confront the US? Probably not. Imperial Japan would probably retain its power throughout much of the 20th century.
Without conquering half of Europe, would the Soviet Union have had any particular power on the international stage? Yes, certainly, but less, and it would have taken far longer to build up.
Without the impetus of war, would America have industrialized and profited during the 40s? Yes, but again, much, much slower. It wouldn’t become a superpower overnight like it did in our timeline.
Heck, without Blitzkrieg and Allied firebombing, Europe’s imperial powers mightn’t have tumbled from grace – they would have finished their slow decay, taking decades more to fully relinquish power over their colonies.
Without the war motive, rocket and nuclear technology simply wouldn’t have been invented. Oh, we’d stumble across it eventually – but not for years and years. Which means no easy end to Imperial Japan, no mutually assured destruction, and no space race.
Can you comprehend the devastation those four changes would have on history as we know it?
The Cold War would be unrecognizable. Instead of a rich, deadly US and a Soviet Union with vast territories, we’d have four major powers: the divisive, decaying empire-states of Europe, the poor but militarized Soviet Union, the gradually wealthy United States and the hungry-for-territory Imperial Japan. The United Nations wouldn’t be formed. The nation of Israel wouldn’t be created. The US wouldn’t control the world’s oceans. Science would crawl on at a leisurely pace.
And we have no way of predicting what the next ‘big war’ would look like, or when it would happen.
History just twisted into something unimaginably different and perverse.
That’s the problem with KHE. The man created World War 2 as we know it. But he didn’t create a World War. Whether or not WW2 as we know it happens, there would be another Big War. Just one. After one big war, nuclear weapons are invented (and probably used), and after that there isn’t another Massive Ground War, because the two are mutually exclusive.
With Hitler alive, we know how the Big War goes. We know that the good guys (mostly) won. We know that civilization survived the creation of nuclear weapons unscathed. We know that 67 years later, the entire globe lives longer, is better educated, and life is generally better.
By KHE… we don’t know how the Big War goes. We don’t know what the aftermath would be. We don’t know who would invent nuclear weapons, or whether the world would truly use them.
We just don’t know.
So here’s my question: do you have enough faith in yourself that you would throw away everything we’ve accomplished, every advance and victory of mankind since 1945, on the gamble that you could do better?
 If you haven’t, the idea is that over time, an insignificant event, such as a single childbirth, can have massive effects, such as the creation of globe-spanning businesses, thousands of descendants, and the creation of spam mail.