Donut of time

A mathematical model of traveling to the past is described

Time travel is theoretically possible, says Professor Amos Ori from the Israeli Technion Institute. His calculations show that in some situations, an object moving through space-time can end up in the same place from where it started, but at the same time will move back along the timeline. However, for now, Professor Ori does not propose to build a real time machine. Humanity now does not have the technical capabilities to create such conditions for leaps into the past to become a reality.

When modern physicists talk about a time machine, they mean something completely different from what an ordinary person might see in a science-fiction film. No flashing lights, powerful magnets, spinning gears - such decorations will not help. Physicists are solving a purely theoretical problem: is it possible to distort space-time so much as to return to the past. Some believe that this is possible, others believe that it is unrealistic or extremely unlikely. But the equations used to prove and disprove these points of view cannot be understood without special education.

But in the roughest approximation, Ori's theory looks like this. A large mass is required, creating enormous gravity. This is where the principles of Einstein's special theory of relativity come into play: it is assumed that under the influence of strong gravity, space-time is curved. Amos Ori, in his work done together with student Dana Levanoni, claims that he was able to calculate the conditions under which the curvature is such that space-time loops, a “donut” is formed. Traveling through this donut results in a time jump back in time. And the more cycles, the deeper in time the moving object descends.

According to Ori himself, his time machine is space-time itself. “If we could create a place in space where we could close the time lines back on themselves, then future generations would be able to return and get to our era,” the professor notes. “But we ourselves, however, will not be able to go back in time, since our ancestors did not create such an infrastructure for us.” Thus, traveling to the past has its own objective limit: until we ourselves create a temporary gravitational loop, we will not be able to see our descendants.

By the way, Ori is far from a pioneer of such research. Before him, many serious researchers were thinking about the nature of space-time, for example, the great Austrian mathematician Kurt Gödel and the famous British astrophysicist Stephen Hawking. Gödel, in particular, back in 1949, published calculations based on Einstein’s equations and proving the possibility of the existence of time cycles. However, this was only a mathematical hypothesis, and physicists themselves, including the father of the theory of relativity, doubted whether such loops existed in reality. The American scientist Kip Thorne proposed his theoretical description of time travel using so-called “wormholes” about 20 years ago. But Stephen Hawking, on the contrary, believed that time travel is almost impossible, since there are many physical limitations for this.

Amos Ori himself has also been dealing with this problem for a long time. Three years ago, his work provided calculations for a temporary vacuum donut, this time an article in the journal Physical Review considers the possibility of matter (dust) inside the time loop. However, humanity is still very far from the practical use of these theories for time travel. If only because Professor Ory's calculations assume the presence of an object with a very large mass, and no black holes or similar objects are observed in the vicinity of the Earth.

Vladimir DZAGUTO