BENDING OF LIGHT IN ELLIS WORMHOLE GEOMETRY

A recent work by Dey and Sen derived the approximate light deflection angle alpha by an Ellis wormhole in terms of proper radial distance l that covers the entire spacetime. On the other hand, Bodenner and Will calculated the expressions for light bending in Schwarzschild geometry using various coordinates and showed that they all reduce to a single formula when re-expressed in the coordinate independent language of "circumferential radius" r(C) identified with the standard radial coordinate r(S). We shall argue that the coordinate invariant language for two-way wormholes should be l rather than r(S). Hence here we find the exact deflection alpha in Ellis wormhole geometry first in terms of l and then in terms of r(S). We confirm the latter expression using three different methods. We argue that the practical measurement scheme does not necessarily single out either l or r(S). Some errors in the literature are corrected.