Question

Why there is no propagating degree of freedom in 3 dimensional gravity?

Answer 1

Explanation:

The Einstein tensor, in turn, is fixed uniquely, through the Einstein field equations, by the distribution of matter. As a result, there are no propagating gravitational degrees of freedom -- the geometry of spacetime at a point is (almost) entirely determined by the amount and type of matter at that point.

Answer 2

Answer:

It is so because the Einstein tensor is fixed uniquely, through the Einstein field equations, by the distribution of matter. As a result, there are no propagating gravitational degrees of freedom -- the geometry of spacetime at a point is entirely determined by the amount and type of matter at that point.