Literary feasibility of time travel

Time travelling is not possible. To be more precise, it is impossible to move in time at will, while doing it in the usual manner is unavoidable.

This matter of fact has not prevented the best brains of all times from studying the nature of time; for centuries philosophers, physicists and other scholars have tried to define it, very often creating contraddictive theories.

For what concerns literature, and in particular science-fiction, it seems as if theorethic thinking about time travelling did not go as far as with other similarly difficult subjects.
Nowadays the hypothesis of colonizing distant planets is considered by science a slight chance, not to mention the existence of alien civilizations.

Nonetheless, science-fiction writers did not allow these limits to stop their creativity, and in their books came out with brilliant ideas to explain the colonization of remote worlds and the exsistance of all types of alien creatures.
The potentially interesting subject of time travelling has been in some way disregarded by writers.

The state-of-the-art in time travelling

In his book "Gold", published in 1995, Isaac Asimov devoted a chapter to the subject of time travelling in science-fiction. Asimov argues that theoretically a person could be sent into the future using such means as near light-speed acceleration or strong gravitational fields.

According to Asimov, the real obstacle to time travelling is represented by the well known paradoxes.
The most famous is about a time traveller going back in time to kill an ancestor; after the murder, the very existence of the killer and his travel in the past become impossible.

Asimov cites H.G. Wells'"The Time Machine", published in 1895, as the first time travel story. In that novel the main character invents a sort of vehicle, with a seat and two levers. Operating a lever the machine starts time travelling, moving the other it stops.

Well's traveller moves in time exploiting the so called "fourth dimension".

Since 1895 the model of time travelling has remained more or less the same. Even in the popular "Back to the future" trilogy "Martin" used a car as a time machine.
In my opinion, time travelling needs to be imagined in a completely new way.

Aristotle and the real time travel

Time travel, has it is generally described, is absurd.

The Greek philosopher Aristotle invented the principle of identity and non-contradiction; to make it simple, this principle means that the same object cannot have in the same time different characteristics.
By example, a red apple cannot be a yellow apple as well, otherwise it would not be the same thing anymore.

The principle of identity and non-contradiction rules out the logical feasibility of time travelling, more than the paradox of murdering one's ancestors.
In fact, let us suppose that, having a brand new time machine parked in my garage, I would like to travel to the year 1900. After fastening the seat-belt and pushing a lever, I look outside and I see horses and charriots, gas lamps, dirt roads.

Am I in the real 1900, the one we read about in history books? According to Aristotle no, because being born in 1976, I have never lived in the year 1900 we all know.
If so, supposing that the time machine worked well, and considering that everything looks like it should in the year 1900, where I am?
In a place very similar to that described in the books, but not the same, because there is one more person that should not be there.

The real time travel could happen if the inventor of the machine was a sort of god, external to the universe, who could send back and forth everything.

If the whole universe could move towards the past or the future at a faster pace, this would be the real time travel.

Obviously this case does not interest anybody, because the main character cannot distinguish himself from the others.

We have made clear that what we intend to do is not real time travel, but something very similar, much simpler according to logic and less of a problem.

The traveller and his machine

Let us go back to my travel to the year 1900. When I finally arrive there, everything looks different, apart from me; nobody knows that in the future there will be Elvis Preasley and the Beatles, while I remember it as I knew it before beginning my travel.
This matter of fact hides a very important truth.
When the time traveller switches on his machine, he is the only one who will not travel in time, while all the others will.
The time traveller is the only one to remain unchanged; he keeps his clothes and the memories of his life. It is arguable if the time machine operates instantly or in a few seconds, but this is a secondary issue.
Let us move ten years into the future or the past; our relatives will look different, while we will be the same.
The metaphor of a vehicle, used by Wells and many others, is deceiving.
The time machine should be represented as a bunker, more simply as a cellar; the time traveller does not feel any acceleration, as he does not suffer any change while everything goes on outside his machine.
The real time travellers are the others, a bit like if Columbus had kept his vessel at anchor in Palos'port, while America sailed towards him. Sure he would not be remembered as a great explorer...

The way around paradoxes

Let us put all parts together; a lonely genius invents a machine that makes it possible time travelling for those who do not enter it, using light speed, gravitational fields or parallel dimensions. He builds his machine in the garage, and one day he enters it, to send the others in the past and kill his grandfather.

The machines starts its travel; the inventor looks at the instruments to check the current date, doubting of the reality of its travel, because he does not feel any motion.
When he finally reaches the right year, he finds his grandfather asleep, and he shoots him with a shotgun.

This sad event does not cause any paradox, because the past where the grandfather is shot is only partially similar to that where the grandfather lived his first life, perhaps dying of too much eating.
The time machine does not completely revert the time flux, but only partially, because the inventor and the machine itself were not involved in the reversal.

At a broader level, first there was a time in which the grandfather lived peacefully, generating sons and nephews; then a partial reversal of the time flux, which brought almost all the universe to a state similar to the previous one; at this point the grandfather was killed. By this moment the nephew was alive, independently from the grandfather.

The type of time travelling which interests science fiction writers is not leaving from A, going to B and coming back to A, but rather A-B- almost A.
You will agree that under the angle of logic, if "almost A" includes the grandfather or not it is totally unimportant.

If the killer time traveller should decide to go back to the future, it would not be the one where he left, but a very similar place ("almost-B") which differs because it does not come after A but it follows "almost-A"; it is impossible go back to B because in the maintime the main character is changed, it is no more the one existing in "B", who did not kill his grandfather yet.

Conclusion

I think that moving back and forth in time for a few decades should not cause any problem to the chrono-ecosystem.

At the end of the day, a grandfather more or less does not make a big difference, let us say so with deepest respect to grandparents.
To evaluate the consequences of time travelling one can apply the same criteria we use in ordinary life; if a butterfly flies east instead of going west, this is very unlikely to cause an earthquake.

The only obstacle towards a complete liberalization of time travelling is the multiplication of time travellers and time machines. In this case a time machine would have an influence on the others, making the plot extremely complex and difficult to follow.
For these reasons I suggest writers to make time travelling a monopoly controlled by a single character.

I hope that these pages may contribute to the success of time travelling as a literary theme.
If you have endured reading till here, let me know what you think about this article, and if you are a science fiction writer, do not forget to quote me in the foreword.