Quantum physics says goodbye to reality Apr 20, 2007 Some
physicists are uncomfortable with the idea that all individual
quantum events are innately random. This is why many have
proposed more complete theories, which suggest that events are
at least partially governed by extra "hidden variables". Now
physicists from Austria claim to have performed an experiment
that rules out a broad class of hidden-variables theories that
focus on realism -- giving the uneasy consequence that reality
does not exist when we are not observing it (Nature 446 871).
Some 40 years ago the physicist John Bell predicted that many
hidden-variables theories would be ruled out if a certain
experimental inequality were violated – known as "Bell's
inequality". In his thought experiment, a source fires entangled
pairs of linearly-polarized photons in opposite directions
towards two polarizers, which can be changed in orientation.
Quantum mechanics says that there should be a high correlation
between results at the polarizers because the