Experimental Metaphysics Testing Quantum Reality

Bell's theorem says the universe at the fundamental level may be unreal and local, or it may be real and nonlocal, or it may be unreal and nonlocal. Experiments now exist to address these sorts of puzzles. There is also practical spin-off for internet security.

"In a Leggett-type experiment (bottom) the correlations between linear polarization for one photon and elliptic polarization of the other can be shown to violate a realistic world view even if instant non-local communication is allowed. As shown in the figure, circular and elliptical polarizations of single photons can be measured by using appropriate combinations of quarter-wave-plates and linear polarizers."

In other words, the world is not real and is not local at the fundamental micro-quantum level.

http://www.quantum.at/fileadmin/Presse/2008-07-01-MG-PW_A_Quantum__Renaissance.pdf