We got accustomed to the usual science fiction concepts of time travelling through timelines, parallel universes and whatever the artist’s mind can imagine. But is the concept of time travelling scientifically possible?
Let’s start from the concept of “time”, that we know to be relative and that can be observed from different points of view. One of these is the idea of time as an increase in Entropy.
Entropy is the level of chaos in a closed and isolated system that, according to the second law of thermodynamics, is constantly increasing.
If we burn a piece of paper in a closed room, we will notice that the molecules of the paper disperse into the room in the form of gas, thus increasing the chaos in the place in question, then the Entropy.
Therefore, it is logical to think that if we invert the same entropy, the molecules of the paper will return to their initial state and position, so the paper will resume the same shape and size as before; we therefore made a real journey through time.
We have managed, in microscopic environments and for very short periods of time, to reverse entropy but the second principle of thermodynamics is, however, so firmand irrevocable that this theory can’t go beyond science fiction.
However, if we think that in the 800s it was physically impossible to get a man to the moon, we can hope that in tens or hundreds of years man can actually do what today we can only imagine and fantasize.