text: Brans-Dicke theory is an alternative to this theory, which was tested in an experiment in which an iron-57 sample emitted gamma rays towards another iron-57 sample placed 22.5 meters away.
full_question: Brans-Dicke theory is an alternative to this theory, which was tested in an experiment in which an iron-57 sample emitted gamma rays towards another iron-57 sample placed 22.5 meters away. This theory was supported by the Pound-Rebka experiment and by Arthur Eddington's observations of a solar eclipse. This theory correctly predicted the difference in the precession of Mercury's perihelion. This theory studies metrics, which are the solutions to the field equation. According to this theory's equivalence principle, gravity is indistinguishable from a pseudoforce. For 10 points, name this theory of Einstein which treats gravity as the curvature of spacetime.
first_sentence: Brans-Dicke theory is an alternative to this theory, which was tested in an experiment in which an iron-57 sample emitted gamma rays towards another iron-57 sample placed 22.5 meters away.
raw_answer: general relativity [or GR; prompt on "relativity"; do NOT accept "special relativity"]