Is quantum entanglement real? Check the experiment

David Kaiser , a professor at MIT, and his colleagues are going to conduct an experiment to confirm the phenomenon of "quantum entanglement," according to the New York Times . This is one of the most interesting phenomena in quantum physics. Fifty years ago, in November 1964, the physicist John Bell proposed an analysis of the Einstein-Podolsky-Rosen paradox (the so-called Bell Inequality) and thus laid the foundation for possible physical experiments confirming or disproving the presence of quantum entanglement.

Measuring experiments in quantum physics has always been associated with certain difficulties - in fact, in the quantum world, the measurement of the state of a particle always affects its state, so scientists have to resort to all sorts of tricks and indirect measurements.

In the case of quantum entanglement, everything is even more complicated. For the experiment, it is necessary to choose which particular property of the particles will be measured. Some of the theories that disprove quantum entanglement argue that although the experimenter is at first glance free to tune the detectors in any way, some event from the past can influence the choice of these settings and thus spoil the purity of the experiment, predetermining the results.
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Kaiser and his colleagues, instead of trying to prove the existence of free will, approached the question from the other side and suggested their own version of the experiment. The choice of detector settings will be determined by the properties of the light emitted by any sufficiently old objects of the Universe, for example, quasars, while located far from each other. Thus, if the result of the experiment is influenced, it should have been formed together with these celestial bodies billions of years ago, soon after the Big Bang.

Quantum entanglement is the ability of a particle to instantly assume a particular state, depending on what state its partner particle takes, regardless of the distance between them. For the first time they started talking about it at the beginning of the 20th century, when physicists argued whether quantum mechanics really fully describes the real world. Einstein was convinced that “God does not play dice,” and that the probabilistic model of quantum mechanics is incorrect, as a result of which a group of like-minded people invented a thought experiment that, from their point of view, refuted quantum physics. However, as it turned out later, such entanglement really must exist, and moreover, it follows from the properties of quantum physics.