Crossword puzzle clue "some were dark"

Source of "Say! In the dark? Here in the dark! Would you, could you, in the dark?"

Some were Dark

Particle physicist whose findings were first accepted by Einstein, but later were shown to be fraudulent

"Wish you were here—__ were there"

"It builds strong bones, but who cares in this dark, dark world..."

Dark as dark can be

Dark purplish-brown to dark red

Some were for The Byrds