Thinking About: Time Travelling 

There has been much chatter (apparently) on social media regarding supposed evidence for Time Travellers including early photographs of people holding mobile phones, carvings of ancients holding laptops and, my personal favourite, a carving of an astronaut on the side of an English medieval church. Most of these are somewhere between silly and nonsensical along with a smattering of ignorance about when things were actually made. 

But (of course) it got me pondering... Is Time Travel even possible – never mind actually recorded in stone or paint. Technically, yes. But... So far, the only way we know of breaking the Time Barrier is by travelling REALLY fast and relying on Time Dilation. As time is perceived as passing much slower inside the vehicle than outside you could travel REALLY fast (maybe doing a loop of the Solar System) and what feels like a few months onboard ship might translate as a few hundred years ‘outside’. The trip however would only be forward and there’s no way back. But what about dialling a date and going there like in the movies? Is that even theoretically possible? 

I’ll be the very first to admit that my knowledge of Temporal Mechanics is largely from watching Star Trek, so non-existent then. But, coming at it from another direction I’m guessing that you’ve probably heard of the ‘Grandfather Paradox’? Basically, it’s the idea that you can’t go into the past and kill your grandfather (or less violently ensure he never meets your grandmother) because you’d never have been born and therefore couldn’t have travelled back to do the deed. Many SF short stories have been based around this idea. But I think this illustrates another bigger problem I’m calling the ‘Everything Paradox’. Imagine you hop in a friends Time Machine and travel back 100 years and appear in an empty field miles from anywhere. You step out of your craft, look around for a while, see or interact with no-one, get back in and come back to the present, arriving ‘here’ mere seconds after you left. No problem, right? Maybe a bit pointless but an OK proof of concept. But... Just being there, in the past were you never existed before has changed things. The movement of air and wind patterns will be different because of you and your craft. You breathed oxygen that wasn’t previously breathed and expelled CO2 likewise. You walked around, maybe stepping on some bugs, making footprints that filled with water later and maybe providing a drink for creatures thirsty enough to have been easy prey for a passing owl later that night. A fox you didn’t even see certainly saw you and changed direction to avoid you. Coincidentally that fox missed meeting up with a passing vixen, who you also didn’t see, and so didn’t father a set of cubs – one of which would’ve been the ancestor of a fox being hunted nearby in a few years, so the politician that would’ve been chasing it didn’t fall off his horse and didn’t break his neck. That same politician went on to take up an important role that would’ve been vacant to a much more able incumbent, so a problem became a crisis, and a crisis became a war. Butterflies and their effects BITE – just ask Homer Simpson. Yet nothing like this has happened in the Time Travellers history, so does that mean nothing CAN be changed no matter what? Are Time Travellers ‘doomed’ to be mere invisible observers unable even to breath ancestral air?  

But if the Time Traveller comes back and nothing has changed what does this actually prove? Does it mean that the past cannot be changed, no matter what? If the Traveller did indeed go back and, for unresolved family issues, successfully kill his grandfather and returns to find that not only does he still exist but his parents are there to greet him on his return and on the way home they swing by grandpa’s house, what does that mean? The problem, I think, is in thinking of Time as an arrow straight line – Past, Present, Future and so on. So, you affect the past (in any way), you affect the Present (in which the Traveller started his travels) and you affect the Future (when he gets back from the trip). This, naturally, gives rise to the dreaded Paradox, but only if Time is indeed Linear. What if it isn’t? 

I think Doc Brown explained it pretty well in Back to the Future II, when Biff used the future Sports Almanac to become fabulously wealthy and mess up the Timeline. Doc’s hypothesis though was based around the idea of a single Timeline. Marty’s actions in the past changed things so his and everyone else’s future was different, and the ‘original’ Timeline simply ceased to exist. The plot of the 2nd film revolved around efforts to put everything (or at least most things) back the way they “should’ve been”. A more logical solution, in my mind anyway, is the idea of the Multi-verse so loved by Marvel Studio. Every act (or inaction) results in a split of the Timeline so that in the Multi-verse everything that could happen does happen. So, getting back to grandpa, a Time Traveller CAN indeed go kill him and come back still existing and still with gramps on his porch because the homicide changed one reality – just not the Travellers reality. Which means, if true (which, honestly, it probably isn’t) you can indeed go into the past, you can fully interact with it, you can change things – radically if you want to – and still return to the completely unchanged world you left. So, no going back and killing Hitler (sorry!), but that’s a discussion for another ‘time’ I think....