Cecil Moore wrote:

The bright interference rings
are four times the intensity of one of the two equal
waves. The dark interference rings are, of course,
zero intensity.

If the intensity of one wave is P, the intensity of the
bright rings will be 4P and the intensity of the dark
rings will be zero.

That's right. And we know that intensity is proportional to the
square of the EM field, so if P=9 then field=3. When there are two
such EM fields superposed, then we have 3+3 squared which is four
times greater than 3 squared. And owing to this supposed
'inequality', we have the sophomoric (literally) notion that there is
"extra" energy which must come from somewhere else.

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