Imagine that you’ve just dropped your favorite scoop of ice cream. The weather’s hot and you’re already a quarter of a mile away from the store where you bought it. It wasn’t even your mistake that you dropped it; the football shouldn’t have hit you in the face. More specifically, it shouldn’t be anywhere near your face, since you weren’t even playing football; you were just walking on the footpath and enjoying the scoop of delight in your hand. Oh well, what can you do? You can’t turn back time, right?
Time travel has been fodder for Science Fiction movies for a long time, but what if I were to say that it is actually possible in this day and age?
The weird thing is that time travel today has nothing to do with today’s technological breakthroughs. In fact, it has been possible since the dawn of time, since the Big Bang itself, since the dinosaurs were barbecued, since the first human walked on Earth, and since the first Justin Bieber song ever gave you nightmares. That sounds like an eternity, doesn’t it? Well, that’s because it has literally been an eternity!
Getting to the point, time travel is possible, and was first explained by a dead German by the name of ‘Albert Einstein’. Most people have heard of him, but if you haven’t, don’t worry… just listen extra carefully to what I’m about to say.
“Get out from under your rock!”
So there’s this brilliant guy named Einstein; I’ll call him Mr. E. One sunny day, Mr. E was doing his own thing, combing his mustache and putting on hair gel, when suddenly he had an epiphany about the universe. The rest, as they say, is history. Mr. E put forward the general theory of relativity, which deals with how matter interacts with space and time. Now, you have to understand that Mr. E was extremely intelligent. He was so clever, in fact, that it is claimed that no one can properly understand the concepts of relativity as well as he did.
According to Stephen Hawking, arguably the smartest man of his generation, any person who claims to fully understand relativity is nothing short of a liar. In other words, when I say that by reading this post you will understand relativity as well as I do, you should know that I’m telling you the truth because, well… “I know nothing”.
But wait! What I DO know, and what I will try my very best to help you understand, is how you can travel in time.
Satellites have been orbiting the earth for almost 70 years now. Some discoveries have shown that the geostationary satellites used for communications and positioning struggle with the problem of time-loss, even with extremely accurate atomic clocks on board. Why could that be?
Relativity shows that when a small object, like a satellite, is in close proximity to massive objects, like the Earth, time moves slower for them as compared to us. This is due to the fact that gravitational forces around the massive object bend the 3-dimensional space around it. Theoretically, with such strong gravity, it’s even possible to bend light. This is where things get spooky! Due to this bending of space time, time appears to move slower for the smaller object. This change, called “time dilation”, is directly related to the mass of the larger object. The change brought about by Earth was measured to be something around 50 micro-seconds, which might seem insignificant for us, but if it goes uncorrected, it causes errors of about 10 km/day in the GPS systems on board. The atomic clocks in the satellites have to be corrected in order to avoid this error.
Look at Time Dilation like this – imagine that you have a tennis ball that has a similarly powerful gravitational field as that of a black hole, but only extends to your body. If you look up at the sky, holding the ball in your hand, you’d have a pretty sweet time-lapse video in about a second. Clouds would just go zipping by and you would have no sense of day and night. You could hold it for 5 minutes based on your watch, but for the normal world, 50 years might have gone by. In a way, you have traveled 45 years into the future, although what you have actually done is merely travel through time at a rate of 10 second/second.
Do you see where I’m going with this? Imagine that there was a massive enough object, such as a big black hole (there’s one at the center of the Milky Way, about 28,000 light years away), and Han Solo were to orbit it for one year. The time dilation he would experience would be spectacular. Imagine him coming home and finding the lovely Princess Leia long dead and Ewoks ruling the universe.
There’s a catch here after all. This phenomena technically only lets you travel forward in time, not backwards. Traveling into the past is relatively difficult. In fact, it has been widely considered paradoxical within the scientific community. Let me explain what that means with an example. Let’s assume that you somehow travel back in time and pull a Tarantino-style shootout with your former self. Your murdered self wouldn’t be able to travel forward through time and eventually travel back to that event, so your very existence would become a paradox. This is not something I would particularly recommend, although it does make for very interesting science fiction.
The take-home lesson here is:
1. Traveling into the future is possible.
2. Traveling into the past… a big no no.
3. Ewoks are scary.
4. You’re stuck with Justin Bieber… unless you find a big enough black hole and then come back when he’s fifty.