“…The ideas of such conformal scattering were taken up by Baez, Segal and Zhou [6][7][8][9] to study a nonlinear wave equation and to some extent Yang-Mills equations on flat space, and later by Mason and Nicolas [33,34] to study linear equations on a large class of asymptotically simple spacetimes constructed by Corvino, Schoen, Chruściel, Delay, Klainerman, Nicolò, Friedrich and others [12,13,15,16,28,29]. This spurred a programme of constructing conformal scattering theories for various fields on a variety of backgrounds and since then a number of works have appeared, many focussing on conformal scattering on black hole spacetimes 1 [23,25,37,39,40]. It should be mentioned that there have been plenty of works studying relativistic scattering theory without employing the conformal method, notably by Dimock and Kay in the 1980s [17,18] and later by Bachelot [3,4] and collaborators Nicolas, Häfner, Daudé, and Melnyk, among many others, a programme which eventually led to rigorous proofs of the Hawking effect [5,35].…”