Have you ever made a mistake in trying to go back in time and fix it? Time travel was considered impossible due to various paradoxes. But now scientists are examining a hypothesis called “Multiple historiesThey are so that perhaps through parallel timelines they can make the idea of time travel at least theoretically possible.
Physicists have been trying to get out of theory for decades General relativity Use Albert Einstein to discover the answer to this question: Is time travel possible? Apparently, equations can now be written that describe time travel and are consistent with relativity. But physics is not just mathematics, and equations are almost meaningless without a connection to a real representation.
What do the opponents of time travel say?
There are two main reasons why time travel equations seem unrealistic. The first problem, which is more objective, is to build time Machine Returns. To produce this device apparently to Wonderful material (Exotic Matter) We need a material with negative energy Is. Everything we see in the world has positive energy. Based on quantum mechanics, matter with negative energy can be theoretically fabricated, but in very small quantities and for a very short time.
However, there is no evidence that it is impossible to produce surprising amounts in sufficient quantities. In addition, other theories may be able to introduce a way in which time travel without matter is surprising. As a result, it can be said that this problem is a limitation of current technologies or our understanding of quantum mechanics.
The second problem is not so objective, but it is much more serious. This problem contradicts time travel with Logic Pays and The paradoxes of time travel Raises. There are different types of paradoxes, but the most problematic ones The paradox of compatibility Is.
This paradox, which is very popular in science fiction, occurs when a change in an event in the past can prevent it from happening now or in the future. For example, suppose you enter your time machine, go back to five minutes ago, and destroy the device. Now that the time machine is destroyed, it is not possible to use it for time travel five minutes later.
But if you can not use the machine and go back in time to destroy the car, the time machine will not be destroyed; So you can go back and destroy it. In other words, the time machine is destroyed only when it is not destroyed. This scenario is inconsistent and inconsistent because the device cannot be destroyed or not destroyed at the same time.
Eliminate the paradoxes of time travel
Many science fiction stories mistakenly say that paradoxes are possible Create are. In these stories, time travelers are warned not to make big changes in the past and not to meet themselves. One of the most famous examples in this field is the Back to the Future cinematic trilogy.
But in physics, paradox is not an event that can happen. Paradox is in fact a theoretical concept that points to an inconsistency within the theory itself. In other words, the paradoxes of incompatibility do not simply mean that time travel is a dangerous act; these paradoxes show that time travel It’s not possible.
This is one of the incentives of the famous physicist, “Stephen Hawking»In presenting the hypothesis«Guess chronological protectionHe said that time travel should be impossible. But this hypothesis has not yet been proven. On the other hand, the world becomes a much more attractive place if, instead of eliminating the possibility of time travel due to paradoxes, we can eliminate the paradoxes themselves.
One of the measures taken by theoretical physicists to solve the paradoxes of time travel, “Igor Dmitrievich Novikov” done. “The journey to the past is possible, but you can not change it,” he says in the “self-adjustment conjecture” hypothesis. According to Novikov, if you want to go back five minutes by car and destroy the device, this will be impossible. Physical laws will somehow protect the compatibility of events.
Introducing multiple histories
If you can not change the past, what is the use of traveling to the past? «Barack Shoshani“He and his two students, Jacob Hazer and Jared Wogan, have shown that Novikov’s hypothesis cannot solve some of the paradoxes of time travel,” says Brock University of Canada, an assistant professor of physics. With this account, we return to the first point; Because even if a paradox is not solvable, time travel will be logically impossible.
However, there are still hopes. Shoshani and his students have shown that there is Multiple histories (in other words, Parallel timelines) Can solve paradoxes. In fact, this hypothesis can not only solve paradoxes that Novikov’s conjecture could not solve, but it can also remove any paradoxes.
This idea is very simple. When using the time machine, enter one when exiting Different timeline You will. In that timeline, you can do anything and even destroy the time machine. This does not change the first timeline from which you came. So since you can not destroy the time machine in the first time line, there is no paradox.
Shoshani says that after three years of working on the paradoxes of time travel, he is now more convinced than ever that time travel is possible, but this will only be possible if our world allows multiple histories. Coexistence Have. Does our world have such a capability?
Is it possible for multiple histories to coexist?
Quantum mechanics supports this theory, especially if you accept Everett’s interpretation of “multiple worlds.” In this interpretation, a history can be divided into several histories Division And each of these histories is an example of a possible event. This Possible events It can be the life or death of a Schrینdinger cat and whether or not you reach the past.
However, these explanations are merely speculative. Shoshani and his students are trying to find a solid theory of time travel with multiple histories that is fully consistent with general relativity. Of course, even if we can find such a theory, it is still not possible to prove that time travel is possible, but at least we can say that time travel will not be considered impossible due to adaptation paradoxes.
Time travel and parallel timelines are always intertwined in science fiction, but now we have to wait to see the combination of the two in the world of science. General relativity and quantum mechanics tell us that time travel can be possible, and if so, multiple histories should be considered possible.