Skip to main content

Killing Hitler is harder than it looks

Sorry, not available for killing
A week or so ago there was a piece on one of the Guardian science blogs on the downside of going back in time and killing Hitler. Dean Burnett points out that this ever-popular time travel fiction theme is not necessarily a good idea. The main arguments against it seem to be the difficulty of deciding when to kill him - not as obvious as you might think (perhaps the best idea would be to make sure he's never born) and the unintended consequences argument. After all, even if taking Hitler out of the historical equation made sure that the Nazi atrocities didn't happen (not of itself a certainty), it could result in a chain of events where, say, an all-out nuclear war breaks out in the 1960s. Would you be prepared to take that risk?

But the post misses the most obvious objection to going back and killing Hitler, which is that it's not possible.

Now, this might seem a silly complaint. After all, almost all science fiction features technology that isn't possible now - and many SF plots require the laws of physics as we know them to be seriously bent or outright broken. But the frustrating thing with time travel is that it is perfectly possible. There is nothing in the laws of physics that prevents it. (It's difficult, admittedly, but it's just an engineering problem.) However, real time travel is very different from time travel in fiction.

Firstly it's a lot harder to go back than forwards, where all fictional time machines seem to make no distinction. But more importantly, any backward time travel based on general relativity (which is the only means we know to make it happen to any significant extent) has a huge limitation. It doesn't involve reversing time - it's more about moving into a space where time has run more slowly and getting to the past that way. And that makes it impossible to time travel to a point before the time machine was first constructed.

So, at a stroke, killing Hitler is out of the window. It doesn't mean there might not be similar dilemmas for those who want to travel into the past once a machine has been created, to stop a future dictator before (s)he gets started. But Hitler is out of bounds.

Sorry, Dean, but killing Hitler is so last century.

Image from Wikipedia


Popular posts from this blog

Why I hate opera

If I'm honest, the title of this post is an exaggeration to make a point. I don't really hate opera. There are a couple of operas - notably Monteverdi's Incoranazione di Poppea and Purcell's Dido & Aeneas - that I quite like. But what I do find truly sickening is the reverence with which opera is treated, as if it were some particularly great art form. Nowhere was this more obvious than in ITV's recent gut-wrenchingly awful series Pop Star to Opera Star , where the likes of Alan Tichmarsh treated the real opera singers as if they were fragile pieces on Antiques Roadshow, and the music as if it were a gift of the gods. In my opinion - and I know not everyone agrees - opera is: Mediocre music Melodramatic plots Amateurishly hammy acting A forced and unpleasant singing style Ridiculously over-supported by public funds I won't even bother to go into any detail on the plots and the acting - this is just self-evident. But the other aspects need some ex

Is 5x3 the same as 3x5?

The Internet has gone mildly bonkers over a child in America who was marked down in a test because when asked to work out 5x3 by repeated addition he/she used 5+5+5 instead of 3+3+3+3+3. Those who support the teacher say that 5x3 means 'five lots of 3' where the complainants say that 'times' is commutative (reversible) so the distinction is meaningless as 5x3 and 3x5 are indistinguishable. It's certainly true that not all mathematical operations are commutative. I think we are all comfortable that 5-3 is not the same as 3-5.  However. This not true of multiplication (of numbers). And so if there is to be any distinction, it has to be in the use of English to interpret the 'x' sign. Unfortunately, even here there is no logical way of coming up with a definitive answer. I suspect most primary school teachers would expands 'times' as 'lots of' as mentioned above. So we get 5 x 3 as '5 lots of 3'. Unfortunately that only wor

Which idiot came up with percentage-based gradient signs

Rant warning: the contents of this post could sound like something produced by UKIP. I wish to make it clear that I do not in any way support or endorse that political party. In fact it gives me the creeps. Once upon a time, the signs for a steep hill on British roads displayed the gradient in a simple, easy-to-understand form. If the hill went up, say, one yard for every three yards forward it said '1 in 3'. Then some bureaucrat came along and decided that it would be a good idea to state the slope as a percentage. So now the sign for (say) a 1 in 10 slope says 10% (I think). That 'I think' is because the percentage-based slope is so unnatural. There are two ways we conventionally measure slopes. Either on X/Y coordiates (as in 1 in 4) or using degrees - say at a 15° angle. We don't measure them in percentages. It's easy to visualize a 1 in 3 slope, or a 30 degree angle. Much less obvious what a 33.333 recurring percent slope is. And what's a 100% slope