After a series of speeches by time travelers, widely covered in popular media, the idea of the reality of the existence of a time machine in the future is growing in the minds of the average man. But, despite a number of theories that admit the possibility of returning to the past in accordance with Einstein's general theory of relativity, none of them, at the moment, has a practical solution that would allow building such a machine.
In addition, over the years, there has been a debate about the advisability of time travel. Moreover, there are many paradoxes that contradict this phenomenon. One of them is called “The Grandfather Paradox”, the essence of which is as follows: “You travel back in time and intentionally or accidentally kill your grandfather during his youth. At the same time, the birth of your parents and yourself becomes impossible … Thus, if you were never born, then who killed your ancestors?"
The example described above is the most popular explanation for the paradox, although it applies to virtually any set of conditions where a possible time traveler changes the past, thereby changing the future from which he came. And although in some cases such theories are mathematically provable, at the moment they are purely speculative.
Despite the popularity of Grandpa's Paradox, there are more complex paradoxes that also make significant arguments against time travel. Consider, for example, a scenario like this:
“A professor of mathematics gains access to a time machine and travels to the future, where he discovers an unknown equation in a mathematics textbook. After returning to the past, he discusses it with one of his students, who is inspired by the idea of developing it on his own. After spending a certain amount of time, the student creates exactly the equation that the professor described, and then publishes a book about it, which becomes the very book that the professor read during his visit to the future."
Everything seems simple … but where is the paradox? Conceptually, the idea of creating the equation did not come from the professor or the student. Each of them learned about it as a result of the professor's journey into the future … and, nevertheless, it already existed. So where, in truth, does the equation come from?
Another version of this same principle, known as the bootstrap paradox, suggests the idea that information can come into the universe out of nowhere. Is it possible? For physicists, this is indeed a troubling proposition, as it contradicts the ordered nature of things as expressed by the well-known laws of thermodynamics. Here we find a close connection between entropy and information in our universe, and thus the idea that information can easily appear "out of nowhere" is akin to breaking these laws. If this is not possible according to the laws that govern our physical universe, then is the concept of "time travel" even viable?
As we said, time travel (at least back to the past) is hypothetically possible and can be achieved in a variety of ways consistent with general relativity. However, if it ever becomes a reality, and information is transmitted from the future to the past, the results can be so strange and unforeseen that we may seriously have to think about such questions: "Who really wrote Beethoven's Fifth Symphony?"
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Voronina Svetlana
