“…WT is of interest to many physical systems for which theoretical predictions have been made and verified numerically or experimentally. We have, among others, capillary waves [7][8][9][10][11][12][13][14] and gravity waves [15][16][17][18] on fluid surfaces, inertial waves in rotating hydrodynamics [19][20][21][22][23][24][25][26], elastic waves on thin vibrating plates [27][28][29][30][31][32], optical waves in optical fibers [33,34], waves in Bose-Einstein condensate [35,36], Kelvin waves on quantum vortex filaments [37][38][39], magnetostrophic waves in geodynamo [40,41] and magnetohydrodynamic waves in space plasmas [42][43][44][45][46][47]. Recently, a theory of WT has been developed for gravitational waves (GW) [48], a few years after their first direct detection [49].…”