Realism in quantum mechanics has been refuted

Local realism disproves

The predictions of quantum mechanics contradict the classical laws of nature. But first of all, it's just a theory. Scientists have been studying for decades whether reality is actually as strange as some of the equations suggest.

A team led by Bas Hensen from the Technical University of Delft has now clearly answered in the affirmative and for the first time ruled out all possible alternative explanations in their experiment. The researchers investigated an inequality that the Northern Irish physicist John Bell (1928-1990) published in 1964. Mathematically, it shows the incompatibility of quantum mechanics with the descriptive classical laws of nature. A key concept here is "local realism". Bell argues that two concepts can be used to classify a theory. On the one hand, it can be "realistic": an experiment only reveals properties of the world that have already existed before. This is not the case in quantum mechanics, since initially only the probability with which an event will occur can be calculated and the system only sets a value when it is measured.

This article is featured in Spectrum of Science February 2016

As a second principle, the "locality" describes when changes in one place can affect another. According to Einstein's theory of relativity, information never travels faster than light. Two things can only interact causally if there is enough time to exchange a signal between them. But in quantum physics, even with particles that are far apart, the measurement of one can have a direct effect on the other - the theory is not local. ...