"Observational science" is a term used by creationists and apologists to try to make their followers believe there is a difference between theoretical physics and what they can perceive with their own eyes, conflating "common sense" and the non-obvious parts of the study of our reality. During the debate between Ken Ham and Bill Nye, the first kept trying to establish "observational science" as an actual thing so that he could say that everything in the Bible is true as Bill Nye couldn't say it