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## Main Question or Discussion Point

pretty straightforward question. for a long time I've been blindly calculating that intensity is (displacement from zero)^2, but never questioned why.

So why is this? I get that by squaring you get a positive value, which helps in, say, quantum probability calculations, but what's wrong with just taking a magnitude of a wave at a given point and calling that the intensity?

is it just one of our arbitrary conventions in physics or is there some real reason?

So why is this? I get that by squaring you get a positive value, which helps in, say, quantum probability calculations, but what's wrong with just taking a magnitude of a wave at a given point and calling that the intensity?

is it just one of our arbitrary conventions in physics or is there some real reason?