Letter of the Week: Polarized

Sir,

To:POP Editor
Subject: Polarizers block non-polarized light?

Sir,

In "Your Questions Answered," (August 2007, p. 106) I read:

"Polarizers are most effective at blocking non-polarized light and thereby
darkening a blue sky when used at a 90-degree angle to the sun's
position on the sky."

Non-polarized light? It might be that that 'non-' sneaked in
inadvertently, but dropping it doesn't do much good to this seriously
flawed statement.