Beware of going back in time; you might never return to the present

By MUNGAI KIHANYA

The Sunday Nation

Nairobi,

19 November 2006

Gregory Kitheka is fascinated by the idea of time-travel. He asks: "if you could go back in time and kill your grandmother, what would happen? I mean, your parents would not be born and therefore you would also not be born. Therefore you cannot go back to kill her!"

Time-travel is so prevalent in science fiction that many people believe it is true. But the reality is that it has never been achieved – it still remains and idea. Interestingly that most of the (fictional) stories on time-travel have people going back in time. A character will either go from the present to the past or from the future to the present. But this may not be a good plan. There is a risk the one may get caught in a time loop.

The theory goes that if you travel back to yesterday, you would not remember that you came from the future. Therefore, you would think and do things in the same way as you had done in the “first round” of yesterday. Then when “today” comes, you would face the same conditions and eventually decide to travel back to “yesterday”. Again you would not remember what had happened and thus you would repeat the process. Consequently, you would get trapped in a loop and would never escape!

But the basic question remains: is time travel possible? Professor Stephen Hawking once said that it is not. His argument being that so far, there has never been any record of people travelling from the future to the present. Thus, there is no evidence that the human race will ever be able to travel in time – unless we assume that “we” are at the leading edge of time, that there is no one ahead of us.

Here is my take on the matter: It is known that space (that which exists between objects) and time (that which exists between events or occurrences) are intertwined. This is popularly called the “space-time continuum”. It is simply an acknowledgement of the fact that you can’t move in space without moving in time as well. That it, when you move, there must be a time lapse between your departure and arrival.

Now, it is possible to travel from point A to B and then back to A. But when you return to A, time will have elapsed. Thus you cannot arrive back at A at the same time you had left. That is, if you travel back in space, you can only return at the starting point at a different time.

With that line of logic, the question that follows is: can one then travel back in time and arrive at a different place (i.e., somewhere he has never visited before)? May be this is the only way that time travel is possible. And if so, the grandfather paradox would never arise because, “you” means all the cells of your body – remember, some of them came from your grandparents. Similarly, Prof. Hawking’s problem is also resolved – the humans from the future can only travel back in time to other planets.