Einstein vs. Bohr, a videogame to contrast two theories of physics

The Big Bell Test, a scientific experiment published in Nature, was conducted with information provided by thousands of users through an online game. The data was analyzed by twelve laboratories from the entire world, and one of them belongs to CONICET.

The video game’s interface. Photo: María Pascual (Kaitos Games)

The Big Bell Test was an experiment conducted on November 30th, 2016. More than 100,000 people participated in a simple video game that required users to generate ones and zeros (bits) randomly. That information was sent to twelve laboratories in which scientist of all continents oriented their studies on atoms, photons and superconducting devices. Through these actions, the objective was to save what is known as loophole from freedom of action.

 In Argentina, the laboratory that participated was the Laboratorio de Óptica Cuántica del Instituto de Investigaciones Científicas y Técnicas para la Defensa (CITEDEF, CONICET- Ministerio de Defensa), with researchers from the Faculty of Exact and Natural Sciences of the UBA. The laboratory is in charge of Miguel Larotonda, independent researcher of the Council.

Over the last century, experts raised the discussion about the view of quantum mechanics which states that particles “change” when they are observed –they are in one state and in the other at the same time-, and they’re not determined for their properties so the measurement cannot change it. For Einstein, there were unmeasured variables that produced that effect. Niels Bohr, however, states that the observable properties did not make sense until they were measured.

“This experiment tends to close the gap between the general public and the ‘strange’ and anti-intuitive concepts of quantum mechanics as it attracts and encourages participants from all parts of the world to produce bits unpredictable sequences, which feed simultaneous and cutting edge technological experiments in a number of laboratories from all the world”, Larotonda affirms.

In 1964, physicist John Stewart Bell proposed a series of conditions for one experiment that could close the methodological traps likely to affect the measures at a quantum level. “Bell proposed a kind of correlations estimator that a system would need to comply with if it worked according to quantum mechanics”, Larotonda explains. Different loopholes were created throughout previous research, but there was last variable missing: freedom of action.

In the measurements on interlaced particles, such as photon, scientists generate and send different locations and analyze some properties of those particles such as color, arrival time or polarization. If the results of those measurements tend to coincide, regardless of what properties we want to measure, that fact would explain that a particle affects the other particle immediately despite being separated by kilometers. This contradicts Einstein’s worldview: the universe would not be independent of our observations.

The results, which were published in Nature, tend to confirm once more that the theory of quantum mechanics is accurate against the local realism proposed by Einstein.