In 1961, physicist and Nobel laureate Eugene Wigner presented a thought experiment which demonstrated one of the least known of the paradoxes of quantum mechanics. The experiment shows how strange nature of the universe allows two observers — for example, Wigner and each Wigner — experience a different reality. Since then, physicists use a thought experiment "friend Wigner" to study the nature of measurement and disputes about whether there are objective facts.
First of all let's talk about the thought experiment, Wigner:
Suppose two men at the same time open the box with schrödinger's cat. If the result (collapse of the wave function) selects the observer, it implies an idealistic decision if the two observers make different choices — there is a problem. If we call one of two outcomes, the choice can only do one of the observers, and supporters of realism rightly consider this solution unsatisfactory.
"In the paradox of Wigner's friend, articulated by the physicist Eugene Vigneron, the following occurs: suppose that, instead of having to watch the cat, Wigner asks to do it my friend. His friend opens the box, sees the cat and then reported the results of his observations to Wigner. At this stage we may say that Wigner had just actualized the reality that includes his friend and a cat. Here is the paradox: whether the cat is alive or dead when Wigner's friend observed her, but before he announced the result of observation? To say that when a friend of Wigner observed the cat, its state is not collapsed, so to say that his friend was unconscious, while Wigner was not asked, that the consciousness of his friend could not solve, live cat or dead, without any prompting from the Wigner".
The Paradox was important because scientists conduct experiments to establish objective facts. But if they are faced with different realities as they negotiate what may be the facts? A thought experiment, Wigner's never been more than that — just a thought experiment.
But last year, physicists noticed that the latest achievements in the field of quantum technologies has allowed to reproduce the test each Wigner in the real experiment, in Other words, the opportunity to create different realities and compare them in the laboratory in order to ascertain whether it is possible to reconcile them.the
And today Massimiliano Proietti from the University of Heriot-Watt in Edinburgh and several of his colleagues said that he first conducted this experiment: created a different reality and compared them. And came to the conclusion that Wigner was right: this reality may be irreconcilable as that it is impossible to agree about the objective facts in the experiment.
Originally a thought experiment, Wigner started with a single polarized photon, which when measured can have horizontal or vertical polarization. But before measurement, according to the laws of quantum mechanics, the photon exists in both States of polarization simultaneously — the so-called superposition.
Wigner introduced a friend to another laboratory, which measures the state of the photon, and stores the result, while Wigner is watching from afar. Wigner has no information about the dimensions of his friend, and therefore forced to assume that the photon and its measurement are in a superposition of all possible results of the experiment.
The Internet can even conduct an experiment to determine whether there is a superposition or not. A kind of interference experiment, which show that the photon and the measurement are in superposition.
From the point of view of Wigner, this "fact" — a superposition exists. And this fact suggests that the measurement could not be conducted.
But his friend does not agree with this because he measured the polarization of the photon and recorded it. Friend may even call Vignera and to say that the measurement was made (provided that the result is not revealed).
Two realities contradict each other. "This calls into question the objective status of facts established by two observers," says Proietti.
That was the theory, but last year Caslav Bruckner of the University of Vienna in Austraia came up with a way to recreate the "Wigner friend" in the laboratory using the methods, including trapping many particles simultaneously.
A Breakthrough, Proietti was that they did it actually. They have implemented advanced scenario "of each Wigner" in the modern experiment with six photons.
Six photons have been entangled to create two alternate realities — one that represents the Wigner and the second of the Wigner friend. Other Wigner measures the polarization of the photon and stores the result. Then Wigner measures the interference in order to understand whether the measurement and the photon in superposition.
The Experiment has produced mixed results. Provides, both realities can coexist, even if they give uncompromising results, as predicted by Wigner. This raises a number of interesting questions that lead physicists to rethink the nature of reality.
The Idea that observers may eventually coordinate their measurements in some fundamental reality, based on several assumptions. First, universal facts do exist and the observers are unable to negotiate.
But there areother assumptions. One of them is that observers are free to make whatever observations you want. And one more thing: the choice that makes a single observer, does not affect the selection of other observers. This assumption is called locality in physics.
If there is an objective reality that all can agree, all these assumptions are correct.
But the result of Proietti and his colleagues suggests that objective reality does not exist. In other words, the experiment suggests that one or more assumptions — that there is a reality with which we agree; that there is freedom of choice; or the locality must be incorrect.
Of Course, there is another option. The possibility that there is a loophole that the experimenters missed. In fact, physicists have tried to close loopholes in such experiments for many years, but they recognize that may never be able to close them all.
However, the work has important implications for science. The next step is to go further: to create experiments that create more and more bizarre alternative reality that cannot be reconciled. Where it will lead us, nobody knows.
You agree that objective reality does not exist? Tell us .
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