Does Travelling Fowards in Time Affect the Present?

If you read this post, then I assume that you will already have read my previous post 'Time Travel - What You Can And Cannot Do'. If you haven't, then please do so now. If you enjoy headaches and being confused, then by all means just carry one reading. Just a friendly warning.

Time travel is a tricky business. For it to work without causing the universe to implode at every point in the space-time latticework that is our rather tangled reality, you need to assume one of two things, one of which is a completely contradictory statement in the nature that it actually disproves the idea that a time machine could work.

   The complex assumption that must be made in order to get rid of the complications that could arise from meddling with temporal affairs and therefore avoid the falling axehead of Health and Safety is this: The Universe is smart and will make everything work out in the end.

   The other assumption one can make is fairly simple by comparison. It says that I'm talking complete nonsense and that time travel is completely impossible on every level, apart from the usual fixed-acceleration forwards direction.

   If you wish to continue further, I suggest that you accept the former as the truth. If you see the latter as the better explanation of the state of semi-fluid temporal muck you find yourself wallowing in then keep reading anyway, if only for entertainment.

Time travel is, as previously stated, a very tricky business.

   Time is not strictly linear. It's not necessarily a progression from cause to effect. From a rather non-linear, outside-looking-in perspective, it's more like a big, wiggly line. At points, bits loop in on themselves, cross themselves and even seem to bulge extra little loops that lead nowhere but back to the source. The basic reality of time means that, assuming all these ideas are valid and actually work in the four dimensional universe (length, breadth, depth and time) that time travel and its subsequent effects would make things generally rather difficult to follow. It's like East Enders gone temporal instead of temperamental. It's not linear; it's non-linear instead.

   First, to the linear side of things. Normal Time is a straight line. Let us identify six points in time, that we shall assume are fixed. I label these points A through F. (See Fig. 1, and I'm terrible sorry for the quality.)

Fig. 1 - A moves through B onwards in a logical progression until it reaches F.

A------B------C------D------E------F

In the above linear diagram, A leads through each point in a sequence all the way through to F. According to my model of time, this is what happens in what you would call 'Normal Time', ie cause and effect.

   Okey dokey. Every thing's fine and dandy up to this point. Now we move deeper into the realm of what I like to call 'Personal Time' (or non-linear time). Personal Time is how a person, eg a time traveller, would view a chain of events that would otherwise be linear in Normal Time. In the case of one who hops about the space-time continuum, this causes some interesting effects.

   Let us look a cause and effect. The idea of cause and effect is that an event (a cause) has a consequence to it (an effect). In Normal Time, this is lovely and works perfectly (though there are exceptions; they shall be explained at a later date). In Personal Time, this isn't exactly the case. It is and it isn't at the same time. It's a matter of perspective. (For the next section, use Fig. 2 as a reference.)

Fig. 2 - Non-linear Personal Time against Linear Normal Time in a simple diagram.

A------B------C------D

A------D------B------C------D

Say you have a time machine. You travel into the future and, from your point of view, this happens first, as you don't experience the time in between the original and destination temporal points. For the rest of the world, this happens later. (The time traveller has gone from point A straight to point D. Refer to Fig. 2 for guidance.)

    There, in the future, you learn that your favourite cat got run over by a car just hours after you departed for the future. (This has happened in real time already. In the eyes of the world, all that is past.) You rush back in time to save your cat, only to scare it by your arrival so that it runs into the road and gets squashed by a truck. Cause and effect have just gotten muddled up.

   Do you see what just happened? From your perspective, the effect comes before the cause, and in fact the effect caused the cause. Here, the cat had already died and was then caused to die. Yet outside your own little mind, things worked out as per normal, albeit for some strange, inexplicable reasons. You scared the cat, and it ran into the road and died, and you learnt of it later on. Therefore, in the outside world cause and effect workejust like that. In your head, it progressed as effect and cause. Look carefully at that subtle difference. It makes a world of difference.

   The complication of this is that you can suddenly swap around cause and effect. At the same time, this seals what happens. Let me explain.

   Back to the story. There are several mistakes you have made. Firstly, building the time machine, which is the root cause of what happens. Let's leave that one for now.

   Secondly, learning of your cat's fate. You manage to not identify the root cause of your feline friend's untimely death and therefore manage to become the root cause. The problem here is not that you try to stop the cat's death. The fact is that the moment you began your trip forwards, it could never be averted.

   Sir Terry Pratchett, author of the phenomenally successful and brilliantly written 'Discworld' series, once wrote in his book 'The Last Hero' of a thing that he called the 'Uncertainty Principle'. (This is just where I first heard about it - it probably exists elsewhere in another format and he pinched it. If not, good on you, Sir Pratchett!) Please bear in mind that this is NOT the Heisenberg Uncertainty Principle. That relates to Quantum Mechanics, which I can't be bothered explaining at this present moment.
   To put it basically, it states that there are a near infinite number of futures, and that if you were to look through, say, a time window into just one randomly selected future, it would become the actual future that would occur. Does that make sense? I'll put it another way. Simply having the knowledge of what will happen alters the structure of space-time, effectively straightening it out a little.

   In the analogy of the flattened cat, simply having the knowledge that the cat did get killed led to its death. By looking at the future, you set in concrete what the past is. This is a rather roundabout way of applying the Schrödinger's Cat theory to time. In essence, you change reality by observing it.
   So we can now ask the question that is the title of this article: can you change the present by travelling to the future? The simple answer is 'yes, you can'. If you want an explanation of how all this works, then just scroll up and reread the article.
   Of course, there are more complex questions that are raised by the answering of this query. What would happen if two time travellers, setting of at exactly the same time, were to head into the future? Would the randomly selected future be the same for them both? If not, them how does that work? Unfortunately for you, I'm not at liberty to explore these avenues.
   (Note from The Editor: In other words, he doesn't know.)
   However, what I can do for you is move on to a new question that is very much connected to the one that I have just answered for you. That question is this.


Can you change history?


I'm afraid you'll have to wait until next time on 'Science of a Sort' (yes, that's what this series of articles is called) to find out. Meanwhile, ponder the problem at hand. Who knows, you may even arrive at the same conclusion that I did.
   Until next time... or is it to be last time? Muhahahaha...