[kordlessagain]

I thought it was going to be about light polarization. Would be interesting if that was also a proximity problem.

As for people, there's a great video that explains this: https://www.youtube.com/watch?v=rE3j_RHkqJc

[dlcarrier]

Nothing in physics is more unintuitive light polarization. Being able to see through a stack of three polarizers, each rotated 45° degrees from the last, but not through two polarizers rotated 90° apart, is pure magic.