Proving Albert Einstein wrong is something that only a small number of scientists can claim to have done but now, more than 100,000 gamers can join that exclusive club and enjoy the smugness that comes with it. In 2016, scientists from around the world led by the Institute of Photonic Sciences in Barcelona (ICFO) asked people to play a simple game online, and the results were used to disprove one of Einstein’s claims about quantum mechanics. The results are published in Nature.
One of the things Einstein truly disliked about quantum mechanics is how the experimenter plays a role in the results obtained from an experiment. He believed the universe to be independent of our actions and quantum mechanics to be governed by the principle of local realism.
This principle tells us that there should be hidden variables in the theory that can explain puzzling effects like entanglement, which Einstein described as "spooky action at a distance". But quantum mechanics works fine without these ideas and scientists have proved this over and over again using the Bell test.
The experiment works like this. Two entangled particles are sent to different locations and their properties and time of arrival are measured. The measurements of one particle influence the other in this kind of experiment, which, according to Einstein, suggests there’s some form of faster-than-light communication. But with quantum mechanics, all is fine. Entangled particles are a single system that shouldn’t be considered independently.
The Bell test has been used over and over again to disprove the principle of local realism. One of the limitations of the test was the “freedom-of-choice loophole”, where the set-up itself might influence the properties. To disprove this the team needed random number generators completely independent of the system. And that’s where the general public comes in.
The project, ambitiously named the BIG Bell Test, hoped to recruit people to play simple games that created a string of zeros and ones. These "bits" were then routed to 12 labs across the world where they were used as random numbers. The live results contradicted local realism with 99.7 percent confidence. Longer experiments over the next few days, still using the randomly generated numbers, showed that the likelihood of local realism being correct is less than one in a trillion.
“The BIG Bell Test was an incredibly challenging and ambitious project," Carlos Abellán, a researcher at ICFO and instigator of the project, said in an emailed statement. "It sounded impossibly difficult on day zero, but became a reality through the efforts of dozens of passionate scientists, science communicators, journalists, and media, and especially the tens of thousands of people that contributed to the experiment during November 30, 2016.”