“First half of a two-volume encyclopedia on physics, aptly?” crossword clue

Reveal the answer to see why it works and where this clue has appeared before.ATOM is the answer to the New York Times crossword clue “First half of a two-volume encyclopedia on physics, aptly?”. It was last seen in the puzzle of January 16, 2025, where it runs at 21 Across and fills 4 squares. It crosses 4 other entries in that grid — those are listed below and are the quickest way to confirm the letters you already have.