h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I think the problem with the polarised photon paradox (if that't the right word) is that you can not create them at 90 degree polarisation without knowing what this is.
But anyway, even if you could not know the polarisation, it does not mean that the individual photons would not.

As a kind of modification to the Schrodinger's Cat idea, it is uttery impossible to know the everything about either photon. BUT, that is not to say we can not know anything about them - we do know that their polarisations are definately out of phase, and that they are fixed.

I have posted some stuff to a thread on Schrodinger's Cat which you might like to read (or disagree with - it's a free internet). The summary is that although it is impossible to determine the state of the photons (or cat) until they interact with something, their state IS fixed - in this case it is fixed relative to each other.

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The more interesting experiment (IMHO) which can be easily reproduced, is the double-slit experiment.
This is where one sends a beam of light through a pair of narrow slits in a screen and get an interference pattern, as one might expect. (I think you might need a beam-splitter here, too.) However, sending a single photon through will result in it hitting the screen at a point which is determined by the interference pattern seen previously. In effect, the single photon is passing though both slits - meaning it took both paths through the beam splitter. This proves that the photon behaved as a wave. However, by blocking one of the slits the photon immediately behaves as a particle!
(I think I have this right - I apologise if the detail is slightly wrong.)