What If A Time Traveler From The Past Appeared?

What If a Time Traveler From the Past Appeared?

The world of science fiction is chock full of plot lines involving time travel, and visitors from the past reaching the modern day. But what if this actually occurred? What would it be like for the time traveller, and how would we react?

Supposing we could do it, bringing someone from the past to the present would likely shock them to the core. Such a shock could have disastrous physical effects, even a heart attack or stroke - especially if the trip was unplanned as far as they were concerned. This “culture shock” would presumably be worse with the more time traversed. The language barrier and cultural differences would increase quickly over just decades, let alone centuries and millennia.

Asking how WE would react to a time traveller is also worth considering. Depending on how far back they originated, our hypothetical traveller could be seen as either through the lens of nostalgia, or as a relic of our ancient past. Of course, the more time the traveller had traversed, the more fascinating it would be to grill him or her for knowledge! Just imagine the historical mysteries and arguments that could be settled by speaking with someone who was actually there! What happened to Amelia Earhart? How about the Lost Colony of Roanoke, Virginia? What was Cleopatra like? How did the Neanderthals go extinct - did we outhunt them, or outright kill them off?

Of course, if a traveller from the past just showed up, without our involvement, we might be pretty sceptical. We’d need extraordinary evidence to prove their claim - verifiable firsthand knowledge that couldn’t be learned from any modern history books. It’s a standard of proof that few could meet.

Technically, forward time travel IS possible . . . although far from practical. To understand how, we have to tackle Albert Einstein's theory of special relativity. The theory proposes that time is relative, passing at different rates for observers travelling at different relative speeds. It implies that time is more than a sequence of events, it’s a fourth dimension, part of a continuum with the three dimensions of space.

The theory allows for forward time travel through a process known as “time dilation”, because time moves more slowly for someone moving at faster speeds. The closer to the speed of light, the more time “slows” down. In fact, astronauts on the International Space Station actually age more slowly than us here on Earth - although the effect is incredibly small. So, hypothetically, if you could blast off into space at relativistic speed and come back, you’d actually be younger than your hypothetical twin on Earth. The principal also holds for those closer to gravitational fields, because gravity curves spacetime.

The more difficult question is whether or not a traveller from the past could go BACK in time, returning to their point of departure. There’s conjecture that this could be achieved through faster-than-light travel, but Einstein’s equations prohibit anything travelling faster than light. Our best bet might be closed timelike curves, loops in spacetime created by cosmic strings or wormholes.

For now, let’s just assume that our hypothetical time traveller came from the past to the present, and was then able to go back again. Such a traveller would be able to return to the past with all the secrets of modern medicine and technologies. He or she might be greeted as a messiah. Then again, too much knowledge could also be dangerous, and could get that traveler killed back at home. They might be labeled insane, dangerous, or even a "witch!"

If this were possible however the ramifications would also be potentially disastrous for us - completely changing our timeline and erasing many of us from existence. Fortunately, this sort of situation seems to defy what we currently know about causality. As far as we know, causes can’t occur after their effects, and effects can’t occur before their causes. If they could, the traveller would be able to take our knowledge, go back into the past, and create a radically different world, meaning that his journey to our present could never have happened as it did.

This is summed up in the famous “Grandfather Paradox”, which poses the question: suppose you travelled into the past to kill your own grandfather before your father or mother’s conception. If you succeeded, you would never have existed to kill him in the first place . . . Which seems to demonstrate that changing the past is impossible.

This is where the idea of parallel universes can be drawn on in lieu of traditional time travel. Perhaps when you travel back in time, you actually arrive in a parallel world, and killing your grandfather leaves your own world untouched. You might then be able to travel forward in time, remaining in the same world as the one in which you were never born . . .

Is such a thing theoretically possible? Well, physicist Lee Smolin spoke with Space.com in 2013 about potential "baby universes," theoretically created through black holes, arising from an equation pioneered by John Wheeler and Bryce DeWhitt. The theory strays from Einstein's idea that time is an illusion, instead offering a hypothesis where time is “real", and moving between quantum realms of a multiverse theoretically possible.

As we can see, a lot depends on the intention and abilities of our visitor from the past, and just how time travel works. Would the time traveller bring with them long dead languages or extinct animals, transforming our historical knowledge and present day ecosystems forever? Would this time traveler see something in our present and return home to prevent it from occurring? Or would time travel open up the world to a whole new idea of trade, knowledge and understanding?

The questions seem to be never-ending, and that's half the fun. Time travel continues to fascinate and excite us to this day, while also inspiring legions of authors and filmmakers along the way. There's a good reason for that, and this endless wellspring of variables is what makes for such a wide open landscape for hypothetical scenarios.