<P> In a small area of spacetime is almost flat and this equation can be written in the operator form </P> <Dl> <Dd> R ^ μ = 2 G c 3 P ^ μ = 2 G c 3 (− i ħ) ∂ ∂ x μ = − 2 i l P 2 ∂ ∂ x μ (\ displaystyle (\ hat (R)) _ (\ mu) = (\ frac (2G) (c ^ (3))) (\ hat (P)) _ (\ mu) = (\ frac (2G) (c ^ (3))) (- i \ hbar) (\ frac (\ partial) (\ partial \, x ^ (\ mu))) = - 2i \, \ ell _ (P) ^ (2) (\ frac (\ partial) (\ partial \, x ^ (\ mu)))) </Dd> </Dl> <Dd> R ^ μ = 2 G c 3 P ^ μ = 2 G c 3 (− i ħ) ∂ ∂ x μ = − 2 i l P 2 ∂ ∂ x μ (\ displaystyle (\ hat (R)) _ (\ mu) = (\ frac (2G) (c ^ (3))) (\ hat (P)) _ (\ mu) = (\ frac (2G) (c ^ (3))) (- i \ hbar) (\ frac (\ partial) (\ partial \, x ^ (\ mu))) = - 2i \, \ ell _ (P) ^ (2) (\ frac (\ partial) (\ partial \, x ^ (\ mu)))) </Dd> <P> where ħ (\ displaystyle \ hbar) is the Dirac constant . Then commutator of operators R ^ μ (\ displaystyle (\ hat (R)) _ (\ mu)) and x ^ μ (\ displaystyle (\ hat (x)) _ (\ mu)) is </P>

When the measured length is less then the actual length the error is known as