In our last edition we tried to explore our galaxy, the Milky Way. I say "tried to" because one page cannot do justice to the
enormity and sheer vastness of our beautiful home galaxy. This time, let's forget all about that for a moment and dwell on a more ambiguous, yet intriguing topic: the possibility (or the impossibility) of time travel.
Now, science fiction writers love the concept of time travel. I'm sure all you movie buffs reading this can think of at least 10 popular movies that directly deal with or feature this phenomenon to a greater or lesser extent, such as Back to the Future, Terminator and Star Trek, to name a few.
What exactly is time travel?
Think of a car parked in the
middle of a straight, narrow road. The car's driver can move it either forward or backward. He can drive slowly, if he likes, and if he's in a hurry, he can always step on the gas.
The choice is his. The point is that he can go in whichever direction he prefers. Now, let's imagine that the road represents time and the car, or more specifically, the driver, wishes to travel along this road of time, in whichever direction he prefers, in a speed of his choosing. Can he do that?
The obvious answer is 'no'. It is obvious because you know for a fact that you can't just go back to
yesterday or last month or whenever and take your term test again. We all, apparently, travel through time at a perfectly uniform rate in one direction only - forward. You just can't change that - unless, of course, you have a functioning time machine of your own.
Let's assume for a moment that some mad scientist somewhere
managed to somehow invent a time machine, by bending a lot of laws of Physics in the process. What would happen if he tried to, say, go back in time by a few decades?
Before we go any further, let me tell you what a paradox is. To put it simply, a paradox is a
contradiction (in laws, rules, etc., etc.) that presents problems and often gets in the way of proving a particular theory; problems that are sometimes unsolvable.
The famous Grandfather Paradox, similarly, presents a huge problem to would-be-time-
travellers. Here's how…
Let's say our mad scientist (we shall call him Siripala), who is 50 years old now, goes back in time to the year 1900. He makes friends with some local hunters of the day and, on a particularly rainy day, decides to go hunting with them in the local park.
Unfortunately, he ends up
accidentally shooting a little boy whom he mistakes for a deer (he IS a mad scientist, after all). Amazingly, by a strange coincidence, the little boy turns out to be Siripala's
grandfather, still a child in the year 1900. Siripala recognises him from a birthmark on his forehead. He is in bad shape after the accident and is rushed to hospital. What will happen to the boy? And what will happen to Siripala if the boy doesn't survive?
Let's stop and think about the
possible consequences. If Siripala's grandfather doesn't survive the injury, he will not grow up to marry Siripala's grandmother who will later give birth to his father. That means, Siripala's father will never exist. If Siripala's father cannot exist then, obviously, neither can Siripala.
What this implies is that if Siripala's accidental shooting ends up killing his grandfather, Siripala should, at least in theory, vanish into thin air - just like that.
That will present another set of problems. If Siripala vanishes into thin air, that is to say, he never
existed, who on Earth invented the time machine, went back in time and accidentally killed his grandfather in the first place?
Makes your head spin, doesn't it?
You haven't heard the last of it.
Opponents of the Grandfather Paradox have found a way to squeeze through the loophole by suggesting that, if Siripala's grandfather doesn't survive, a new parallel universe will be created in which Siripala's family does not exist - at all. Another, far easier to digest idea is that the boy will not die. Even if Siripala tries to shoot him again, something will
happen to prevent him from killing his future grandfather; for instance, the gun will not load, or the bullet will be blank, etc.
Theoretically, time travel is not impossible. We all travel through time (forward at a uniform rate). The question is whether or not we could alter the direction and speed in which we travel through it. Obviously, the technology required for such a feat is far from being up and running any time soon.
And according to some scientists, it is unlikely that we will ever succeed in going back in time. As proof for this claim, these scientists point out that we've never had any "visitors" from the future - implying that no one in the future has invented a time machine. Optimists, however, argue that any visitors from the future would probably want to be discrete about their visits in order to prevent mass hysteria and panic. Others say that it is indeed possible to
'accelerate' the rate at which we
travel forward in time - in other words, it may be possible to travel to the future but not so to the past.
There is one minor detail most
science fiction writers tend to forget when writing about time travel: the concept of spacetime and the
implications of Einstein's theories of general and special relativity. And that, dear readers, is another can of worms altogether. Maybe some other time…
Till then, happy star gazing!