# Can we distinguish between two mass distributions in spacetime having the same effect over a test partlicle [duplicate]

Einstein's equation is

$$8πT_{ab}=G_{ab}$$

where the left side contains the stress-energy tensor and the right side contains the Einstein tensor.

Is there exactly one unique stress-energy tensor corresponding to a given spacetime curvature? Or is it possible for one curvature (i.e. one spacetime metric) to be produced by multiple different mass configurations

• 1. This is exactly the same as your earlier question. Why did you repost it? 2. You keep using "stress-energy" and "mass configuration" interchangably. They're not, since massless things also contribute the stress-energy (notably electromagnetic fields). – ACuriousMind Mar 22 '16 at 12:49
• Because the last question was incoreclty done – Коцето Райчев Mar 22 '16 at 15:25