There is hardly a person on Earth todaywho has never thought about time travel. This is largely due to popular culture - since its inception, the concept of time travel has entered culture and influenced our perception of time. As he writes in his book Time Travel. History "American writer, historian of science James Glick, the very concept of such travel - a little more than a hundred years. So, according to the Oxford English Dictionary, the term "time travel" first appeared in English in 1914 - a reverse word formation from Wells' "Time Traveler" (as science fiction writer Gerber Wells calls the main the hero of his novel "The Time Machine" (1895)). It turns out that in some incredible way, most of its history, humanity lived without wondering what it would be like if they went to the past or the future. Now, physicists at the University of Cleveland have resolved the age-old paradox by proving that, in terms of mathematics, time travel is theoretically possible.
The grandfather paradox
In a study published in the journalClassical and Quantum Gravity physicists at the University of Queensland used mathematical modeling to reconcile Einstein's General Theory of Relativity (GR) with classical dynamics. Einstein's theory allows for the possibility that a person, using a time loop, travels back in time to kill his grandfather. However, classical dynamics dictate that the sequence of events following the death of the grandfather will end with the time traveler ceasing to exist.
British The Independent quotes the wordsthe authors of the study, Germain Tobar and Fabio Costa, that they have puzzled over the years over how the classical dynamics might match Einstein's predictions. Their reflections eventually led to the creation of a mathematical model designed to find out whether the two theories could coexist. The model is based on, oddly enough, the coronavirus pandemic.
Let's say you've traveled in time tryingstop Covid-19 patient zero from contracting the virus. However, if you stop that person from getting infected, it will remove the motivation for you to come back and stop the pandemic. It's a paradox - an inconsistency that often leads people to think that time travel cannot happen in our universe. It is logically difficult to accept, because it would affect our freedom to do any arbitrary action. This would mean that you can travel in time, but you cannot do anything that would cause a paradox to arise.
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Despite the fact that mathematics itself is difficult, itcomes down to something pretty simple. The time travel discussion focuses on closed curves like time, as first suggested by Albert Einstein. Both Tobar and Costa believe that as long as only two parts of the whole scenario in the framework of Special Relativity (SRT) are still in "causal order", the rest is subject to free will.
In the coronavirus patient zero example, youyou can try to stop the infection of patient zero, but you will catch the virus and become patient zero yourself, or it will be someone else. Whatever you do, the main events will simply rearrange around you. This will mean that no matter what you do, a pandemic will happen, giving your young self the motivation to come back and stop it.
No matter how hard you try to create a paradox, eventswill always adjust to each other to avoid any inconsistency. A number of mathematical processes that the researchers have discovered show that free will time travel is logically possible in our universe without any paradox.
While this sounds frustrating to someone trying to prevent a pandemic or kill Hitler, it helps mathematicians understand how we think about time. Either way, new research suggeststhat anyone who ends up devising a way of meaningful time travel can do it and experiment without the hidden fear of ruining the world - at least not right away.
The new discovery is also remarkable in thatsmoothes the problem with another hypothesis, according to which time travel is possible, but the travelers themselves will be limited in what they do - this stops them from creating a paradox. In such a model, time travelers can do whatever they want, but paradoxes are impossible.
See also: Is Time Travel Possible?
But despite the numbers and results obtained,The main problem with time travel is the distortion of space and time required to get into the past - the time machines that scientists have developed so far are so highly reliable that they currently exist only as calculations on the page. Still, the researchers are optimistic, because their work assumes that we will be free to do whatever we want with the world in the past: it will rebuild accordingly.