Asymptotic behavior of null geodesics near future null infinity. III. Photons towards inward directions
Asymptotic behavior of null geodesics near future null infinity. III. Photons towards inward directions
A new sufficient condition for photons emitted near future null infinity to reach future null infinity is derived by studying null geodesics in the Bondi coordinates in asymptotically flat spacetimes. In our previous works [arXiv:2106.03150, arXiv:2110.10917], such a condition was established for photons emitted in outward or tangential directions to …