The Quantum Randi Challenge

The observed violations of Bell inequalities have implications which are difficult to accept for many people, thus, pseudoscientific rejection grows. The nature of the issue is such that well meaning defenses of science often end up benefiting those pseudoscientific claims. Now what? The James Randi Educational Foundation famously offers one million US dollars to anyone who can demonstrate paranormal abilities under laboratory conditions. It has helped stem the spread of pseudoscience. Three characteristics are crucial for its success; remember them via the mnemonic “No Easy Reward”:

Randi-No: The challenge can not be met (according to the established laws of nature).
Randi-Easy: If the pseudoscientific claims were correct, it could be easily met.
Randi-Reward: Meeting the challenge would result in enormous rewards.

The simplicity of Bell inequalities, the classicality of claimed alternatives to Quantum Mechanics (QM), and several other aspects allow a ‘Randi approach’, called “Quantum Randi Challenge” (QRC).

A Randi-challenge allows pointing to the mere existence of the challenge to contest pseudoscience. The challenge not being met, in spite of Randi-Easy and Randi-Reward, argues that the claims are false, convincing even those who cannot grasp intricate mathematical details. That classical computers can model local realistic systems is clear: everything in a computer depends on locally present data and all variables have definite values at any time (they are thus ‘real’), even if they change randomly. Therefore, the QRC can be a “computer game”; the challenge is to modify it so that reliable Bell violation arises:

Randi-No: Bell has proven that a violation of Bell inequalities cannot arise with Local Realistic Hidden Variables (LRHV).
Randi-Easy: The challenge is to reproduce only and nothing else but the behavior of the simplest EPR setup that violates Bell’s inequality maximally, which includes only two angles for each of the two detectors and only 800 entangled photon pairs are to be modeled. The main computer program is already provided via several simple versions with different example models [1]. A challenger would only need to enter the hidden variables and/or measurement prescriptions of her model. Turning any particular measurement prescriptions of LRHV into program instructions is trivial.
Randi-Reward: Instant fame is assured. Since a two or three-computer setup (Alice, Bob, and Carl) constitutes a real classical physical system, a Nobel Prize would be deserved for whoever modifies the hidden variables and measurement prescriptions so that Bell inequalities are violated like QM predicts (about 99 times out of 100 runs while preserving anti-correlation).

The QRC rejects classical models by teaching simple physics; there is no direct interaction with challengers, which is, by the structure of the challenge, unnecessary. For that to work, the QRC must be as simple as possible. It therefore [2] involves the original Bell proof and Bell inequality, thus proving the relevance of Bell’s work still today: It is the minimum sophistication which even the QRC cannot avoid. By its challenge, the QRC thus argues that Bell inequality violations are strictly about something fundamentally different from local realistic, i.e. classical models.

Sascha Vongehr

National Laboratory of Solid State Microstructures
College of Modern Engineering and Applied Sciences
Department of Philosophy
Nanjing University

published online on 4 Feb 2014


[1] S. Vongehr, Quantum Randi Challenge and Didactic Randi Challenges, arXiv:1207.5294v3.

[2] S. Vongehr, Exploring inequality violations by classical hidden variables numerically, Annals of Physics 339, 81 (2013), extended preprint with Mathematica programs at arXiv:1308.6752