Researchers at the University of Surrey in the UK have found no evidence in quantum physics that time travel is prohibited. The work is theoretical and has not been confirmed by experiments. However, it does excite the imagination with the potential feasibility of time travel, which is unfortunately incompatible with classical physics and the world we live in.
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In their study, which was published in the journal Scientific Reports, the scientists talked about their search for the origins of time. They sought to find a physical quantity or its material embodiment that would be responsible for the flow of time. The team failed to find what they were looking for, but their time and effort were not wasted. From the calculations they performed, it follows that in the world of quantum physics — there, in the very depths of the microworld, where everything is arranged differently than in the macroworld — there is no formal ban on the flow of time in the opposite direction.
There is nothing more precise in the world than the equations of quantum physics. With due diligence and expenditure on experiments, the theoretical result can coincide with measurements up to the twelfth digit after the decimal point. Therefore, almost any mathematically correct calculation can be confirmed experimentally. This means that many fantastic projects today, which for various reasons cannot yet be tested in practice, may eventually become reality.
The absence of a theoretical ban on evolution backwards in time could be one of such discoveries. However, in practice, this does not mean the possibility of traveling to the past. The whole point is that the researchers did not study movement and displacement in the usual sense, as in science fiction, but the evolution of the quantum properties of elementary particles. It is important to note that the scientists showed that their work does not contradict the laws of thermodynamics. When the time vector is turned into the past, entropy decreases only within the quantum system, but in the classical system it continues to grow.
To carry out the calculations, the scientists used the so-called Markov chain, or Markov thermodynamics. This is an open quantum system whose evolution depends only on its current state and has no memory. In other words, its future state does not depend on the past. Calculations show that the quantum states of the elements of such a system are capable of evolving with equal probability both into the future and into the past. For the system, it makes no difference in which direction the time vector is directed. In the quantum world, there is no mechanism that could prevent the flow of time from being “reversed”.