Spin It! Time Travels Are Possible if Universe is Rotating, Study Suggests
NASA’s James Webb Space Telescope has produced the deepest and sharpest infrared image of the distant universe to date. Known as Webb’s First Deep Field, this image of galaxy cluster SMACS 0723 is overflowing with detail.
Being able to go back in time and erase all of one’s mistakes is a long-held dream of mankind, described by many science-fiction and fantasy writers. However, people must ask themselves – is time travel even theoretically possible?Over the course of years, many prominent scientists have obtained theoretical calculations, suggesting that one can turn back time – under certain conditions.The theoretical justification for time travel is contained in the 1949 work “An Example of a New Type of Cosmological Solutions of Einstein’s Field Equations of Gravitation” by renowned Austrian mathematician Kurt Gödel. The scientist was a close friend of Einstein, whose work and discoveries he used.© AP PhotoAlbert Einstein presents the first Albert Einstein Award for achievement in the natural sciences, to Prof. Kurt Godel (second from right) and Prof. Julian Schwinger (right) at Princeton, N.J., March 14, 1951, Einstein’s 72nd birthday.(AP Photo)
Albert Einstein presents the first Albert Einstein Award for achievement in the natural sciences, to Prof. Kurt Godel (second from right) and Prof. Julian Schwinger (right) at Princeton, N.J., March 14, 1951, Einstein’s 72nd birthday.(AP Photo)The movement of objects in time and space can be simplified into a curve that connects the past with the future. It is the past that affects the future, because the causes are in the past.In classical physics, one event can affect another only if the first occurs before the second. In the special theory of relativity, another condition is added – it states that nothing can move faster than the speed of light. Gödel showed that closed time-like curves can also be derived from one of the solutions to Einstein’s equation. Since the curve is closed, the object moves along it not only forward in time, but also backward, which is how the theory of time travel was legitimized. As part of his solution, Gödel introduced the assumption that the universe can rotate. The gravitational force then bends space and time in such a way that not only forward, but also backward time travel becomes possible.The behavior of all elements in the universe in Einstein’s theory – in our space-time – is described with four-dimensional lines, a kind of “longitude-latitude” of any physical bodies, simultaneously in space and time. According to Gödel, due to the rotation of the universe, these four-dimensional lines – “world lines” – are curved so strongly that they curl into a loop. If someone assumes that they try to travel along such a world line, one would eventually meet oneself, returning to one’s past.CC0 / Pixabay / Clock
ClockThe possibility of backward time travel creates paradoxes and violates our understanding of how things happen. While studies indicate that the universe is not rotating, Gödel used his calculations to argue that General Relativity is incomplete, and he may be proven right – which means that the possibility of time travel is still on the table.
Theories Explaining Temporal Paradoxes
At the same time, some scientists have put forward various limiting principles in order to resolve the contradictions of the temporal paradoxes:Any closed time-like curve passes through the black hole, which makes the violation of the causality principle invisible to the observer.Nobel Physics laureate Roger Penrose formulated this assumption in 1969 and called it the “Cosmic Censor Hypothesis.” The principle states that singularities exist only in those regions of space-time that are inaccessible to the external observer (for example, beyond the event horizon of a black hole). That is, if time travel is possible, no one can see it.Time travel is possible, but only if it does not violate the principle of causality.Igor Novikov formulated the principle of self-consistency in 1991. According to the hypothesis, closed time-like curves can exist in principle, but they connect globally “self-consistent” events. Then the actions of a time traveler could only lead to local changes, and the probability of an action changing an earlier event on the same curve is effectively zero.Time travel is only possible on a submicroscopic scale.Finally, in 1992 Stephen Hawking proposed limiting the scales on which time travel is possible. He formulated the chronological immunity hypothesis, which suggests that closed time-like curves can exist only on submicroscopic scales.
