Theoretical physicist Ben Tippett of the University of British Columbia, along with University of Maryland astrophysicist David Zang, have created what they say is a working mathematical model of a "time machine" that uses the principle of curvature of the space-time of the universe. The research and findings of the scientists were published in the journal Classical and Quantum Gravity.
Scientists, based on the general theory of relativity, deduced a mathematical model, which they called TARDIS or Traversable Acausal Retrograde Domain in Space-time ("Passable acausal retrograde zones in space-time"). But do not rush to rejoice at the opportunity to visit your long-deceased grandmother in the past, scientists say. There is a problem that does not allow checking the correctness of their mathematical model, but more on that later.
“People think of time travel as fiction. In fact, we think it's impossible just because we haven't actually tried to do it yet,”says theoretical physicist and mathematician Ben Tippett.
"However, a time machine is possible, at least mathematically," adds the scientist.
The scientists' model is based on the idea of the presence of the fourth dimension of the Universe, which is time. In turn, this allows us to assume the existence of a space-time continuum, in which different directions of space and time are connected by the fabric of the Universe.
Einstein's theory of relativity links the gravitational effects of the universe to the curvature of spacetime, the phenomenon behind the elliptical orbits of planets and stars. In the presence of "flat" or non-curved space-time, the planets would move in a straight line. However, the theory of relativity says that the geometry of spacetime becomes curved in the presence of very massive objects, causing them to orbit the stars.
Tippett and Tsang believe that not only space can be curved in the universe. Under the influence of an object with a large mass, time can also be curved. They cite space around black holes as an example.
“The course of time movement inside space-time can also be curved. Black holes are an example. The closer we get to them, the slower time starts to flow for us,”says Tippett.
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“My model of a time machine uses curved space-time to make time for passengers a circle rather than a line. And movement in this circle can send us back in time."
To test the hypothesis, scientists propose to create something like a bubble that can carry everyone who will be in it through time and space along a curved trajectory. If this bubble moves at a speed higher than the speed of light (according to scientists, this is also mathematically possible), then this will allow everyone who is in the bubble to move back in time.
The idea becomes clearer when you look at the scheme proposed by Tippet. There are two characters in it: one is inside the bubble / time machine (person A), the other is an external observer who is outside the bubble (person B).
The arrow of time, which under normal conditions (that is, in our Universe) always moves forward, in the presented scheme makes the past become the present (indicated by black arrows). According to the scientist, each of these people will feel the movement of time differently:
“Inside the bubble, object A will see B's events periodically change and then reverse. Outside the bubble, observer B will see that two versions of A are coming out of the same location: the hour hand is turning to the right and the other to the left."
In other words, an outside observer will see two versions of objects inside a time machine: one version will evolve forward in time, the other backward.
It all sounds, of course, very interesting, but Tippett and Zang say that we have not reached such a level of technology that this hypothesis could be tested in practice. We simply do not have materials suitable for the construction of such a time machine.
“Although from a mathematical point of view it might work, we cannot build such a machine to travel within space-time, since we do not have the necessary materials for this. Exotic materials are required here. They will allow space-time to bend. Unfortunately, science has not yet invented anything like that,”says Tippett.
The idea of Tippett and Zang echoes another idea of a time machine, the so-called Alcubierre bubble, which should also use exotic materials to move in space and time. Only in this case we are not talking about circular motion in the space-time field, but about motion by compressing space in front of you and expanding it behind.
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Previously:
Physicists at the University of Queensland in Australia have set themselves a challenge.
simulate a computer experiment that will prove the possibility of time travel at the quantum level, predicted back in 1991.
They managed to simulate the behavior of a single photon, which passes through a wormhole in space-time into the past and enters into interaction with itself.
Such a trajectory of a particle is called a closed timelike curve - the photon returns to the original space-time point, i.e. its world line becomes closed.
The researchers looked at two scenarios. In the first of them, the particle passes through the mole, returning to its past, and interacts with itself. In the second scenario, the photon, forever enclosed in a closed timelike curve, interacts with another, ordinary particle.
According to scientists, their work will make an important contribution to the unification of two great physical theories, which until now had little in common: Einstein's general theory of relativity (GR) and quantum mechanics.
Einstein's theory describes the world of stars and galaxies, while quantum mechanics studies mainly the properties of elementary particles, atoms and molecules.
- Martin Ringbauer, University of Queensland
Einstein's general relativity admits the possibility of an object traveling backward in time, which falls into a closed time-like curve. However, such a possibility can cause a number of paradoxes: a time traveler may, for example, prevent his parents from meeting, and this will make his own birth impossible.
In 1991, it was first suggested that time travel in the quantum world could eliminate such paradoxes, since the properties of quantum particles are not precisely defined, according to the Heisenberg uncertainty principle.
In a computer experiment, Australian scientists were the first to study the behavior of quantum particles in a similar scenario. At the same time, new interesting effects were revealed, the appearance of which is impossible in standard quantum mechanics.
For example, it turned out that it is possible to accurately distinguish the different states of a quantum system, which is completely out of the question if you stay within the framework of quantum theory.