Sunday, November 4, 2012

The possibility of reversing time by moving faster than the speed of light


Yup, I’m really going to do it.

Alright, so I think I have at least an “okay” understanding of how you can move back time by going faster than than the speed of light. And when I say “okay”, I mean a terrible, terrible understanding. I swear, this kind of thing is probably the number one reason why scientists quit their jobs and become sales executives. It is freaking difficult to understand. Luckily, I managed to get a rather simple explanation on the internet that explained everything really well. Thank god.

Now that I have finished complaining, let’s get back to the subject. Firstly, why do people think that going faster than the speed of light can let you go back in time? Well, to start off, I want you to imagine space and time put inside a graph.


(By the way, got the idea of using a graph from Horrible Science)

And then let’s put yourself into the graph. (The red dot will represent you)

Let’s say you are sitting down doing absolutely nothing.

Graph 2

As you can see, you have not moved, so the space that you have moved is 0. Also, no time has passed, so the time that has passed is (surprise!) 0.

Now, let’s say you sit around for 2 hours doing nothing because you are super lazy.

Graph 3

Congratulations! You have done nothing! Don’t you feel proud of yourself?

Since you have not moved at all, the space that you have moved is still 0. However, what is interesting to note is that the red dot which represents you has also moved. The dot has “travelled” up 2 hours in the graph.

‘So much for that. To make it more interesting, let’s say that you decide to get up and run 3km in 1 hour for no reason.

Graph 4

This time, you have moved through both space and time. You have “travelled” 1 hour into the future and 3km in space, which shows that you can move in both space and time at the same time. By the way, if this seems a bit obvious, don’t worry, it is connected to what I am going to explain later.

So now that we have familiarized ourselves with this arrangement, we are going to learn two extremely important facts. It is very important that you know this fact, as they are the whole basis on how you will be able to travel back in time.

Let’s start with the first rule:

Rule #1: When we are standing still, doing nothing, we are “travelling” through time at the speed of light.

No matter where we are, we are always “travelling” through time. For example, in our graph, we “travelled” through time, from 0 hours to 2 hours to 3 hours. However, the big question we want to ask here is, how fast are we travelling through time?

Well, the rule says that we are travelling through time at the speed of light. That is ridiculously fast. It is super duper ultra fast. To be exact, 299 792 458 metres every second. But don’t bother with the numbers now. Just remember that when we are doing nothing, we are travelling through time at the speed of light. (If you are wondering how people discovered this, I think I will cover that in a later post) Try to wrap your head around this, and don’t continue until you do.

All right, so we are travelling through time at the speed of light. So what? Well, this is where the second important rule comes in.

Rule #2: The faster we move, the slower time passes. (Aka. The Pushing Machine Rule)

Okay, so we now know that we are moving through time at the speed of light when we are doing nothing. But how are we moving? Who is moving us? Why, it is none other than The Great Pushing Machine! (Okay, not really. But this is an analogy.)

The Pushing Machine is the one who can push us through space and time. The Pushing is very powerful, and it has just enough energy to push us at the speed of light. When we are sitting there, doing nothing, like good little humans, the Pushing Machine moves us through time at the lightspeed! (aka 299 792 458 m/s)

However, humans tend to be very hyperactive, and they don’t like the idea of staying still for their whole life. Therefore, when a human wants to move at 3m/s, the Pushing Machine has to use up some of its energy to help the human move 3m/s. (Because the Pushing Machine moves us through space too, remember?) 

But what now? Because it used up some energy to help us move through space, The Pushing Machine doesn't have enough energy to move us at lightspeed anymore! It can almost do it, but not quite. It can only push you through time at 299 792 455 m/s now. (Because 299 792 458 – 3 = 299 792 455. Simple Math.)

What this means, is that when you are moving, time will slow down. As long as you are moving, you are moving through time at a slower pace. Here are some examples:

The fastest cheetah can travel at 98km/h, and it is moving through time at around 299 792 428 m/s.

The world’s fastest car can travel at a max speed of 429km/h, and it can move through time at 299 792 309 m/s

The fastest spacecraft can go at 62856 km/h, and it travels through time at 299 774 998 m/s.

As you can see, even our fastest creations don’t go anywhere close to the speed of light, so we will have to do a little bit of imagining if we want to get some results.

Alright, so imagine you are on a super fast spaceship that is travelling at 299 792 457 m/s. (That’s only 1m/s less than the speed of light.)  Because the Pushing Machine has to use up so much energy to help move you through space, you are only moving through time at 1m/s! This, I must add, is very, very slow.

(In fact, if you took this spaceship and drove around at that speed for 1 year, and then came back to where Earth was, 299 792 458 years would have passed! )

Now, let’s get weird. What would happen if that spaceship could travel at the speed of light, namely 299 792 458 m/s? All the rules of science say that it is impossible to go at that kind of speed, but what would happen if you did, how fast would time go? Well, the thing is, at that kind of speed, time wouldn’t move at all. That’s right, the Pushing Machine has to use up all of its energy to push you through space, so it can’t push you through time at all. You could drive your spaceship around and around, for millions of years, and you would still be the same age.

And now, to get ultra weird. What if you could travel faster than light? This is the big question that we wanted to answer since the start of the post. What if you could travel at, let’s say 299 792 459 m/s (1m/s more than the speed of light) How fast would you be travelling in time? Well, to calculate that we will have to take 299 792 458 – 299 792 459 = –1. You are travelling through time at –1 m/s! That means that you are travelling backwards in time! Indeed, there is a theory that if you can travel faster than light, then you can travel back in time. Holy god. That is awesome. We could travel back in time  and see all sorts of cool stuff, maybe even affect them. We could stop world wars, we could warn people about impeding natural disasters. There’s lots of things we could do if we could travel back in time! So what are we waiting for? Let’s go!

Hold on a second, there’s a catch. As mentioned before, all the rules of science say that it is impossible to go at the speed of light, let alone faster than it. Why? Well, for starters, you would need an infinite energy source to blast yourself at that kind of speed, and so far we haven’t found any infinite energy sources. And even if you did manage to find one, there is a small problem that comes up when you are travelling at the speed of light. You have infinite mass. Which not only sucks for your figure, but also our bodies are not meant to take that kind of weight.

So there you have it. The theory of the whole faster-than-light backwards time travel. This is a really confusing topic, so if you managed to get through it all without losing the plot somewhere, give yourself a pat on the back. Be warned, though, this is a REALLY simplified version of the real thing. There’s still lots of other things to consider, like general relativity, frames of reference, and tons of other scientific nonsense. Still, this is a really interesting subject, I might want to come back to this on a future post, where I will talk about how people managed to discover the two rules above and if there is anyway to bypass the whole infinite energy/mass law. 

But for now, thanks for reading!

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