Back مبدأ التكافؤ Arabic Прынцып эквівалентнасці сіл гравітацыі і інерцыі Byelorussian Принцип на еквивалентност Bulgarian Principi d'equivalència Catalan Princip ekvivalence Czech Эквивалентлăх принципĕ (физика) CV Ækvivalensprincip Danish Äquivalenzprinzip (Physik) German Αρχή της ισοδυναμίας Greek Principio de equivalencia Spanish
The equivalence principle is the hypothesis that the observed equivalence of gravitational and inertial mass is a consequence of nature. The weak form, known for centuries, relates to masses of any composition in free fall taking the same trajectories and landing at identical times. The extended form by Albert Einstein requires special relativity to also hold in free fall and requires the weak equivalence to be valid everywhere. This form was a critical input for the development of the theory of general relativity. The strong form requires Einstein's form to work for stellar objects. Highly precise experimental tests of the principle limit possible deviations from equivalence to be very small.