Loophole-free Bell test
In 1935, Einstein asked a profound question about our understanding of Nature: are objects only influenced by their nearby environment? Or could, as predicted by quantum theory, looking at one object sometimes instantaneously affect another far-away object? Einstein did not believe in quantum theory’s prediction, famously calling it “spooky action”.
Exactly 80 years later, a team of scientists led by professor Ronald Hanson from Delft University of Technology finally performed what is seen as the ultimate test against Einstein’s worldview: the loophole-free Bell test. The scientists found that two electrons, separated 1.3 km from each other on the Delft University campus, can indeed have an invisible and instantaneous connection: the spooky action is real.