There are the 3 considered outcomes for the universe - continued expansion, reaching a static astrophysical plane or gravitational collapse. No matter the outcome, if there is a standing wave the length (why would you have 1.5 times or anything other than 1 !?) Then under the expansion, statis and contraction scenarios, only one of these would ever reach stasis, all other scenarios have a standing wave in flux.
In ATR FTIR (attenuated total reflectance Fourier transform infra-red spectroscopy) evanescent waves penetrate outside the medium to complete the Quantisation rule. Would the same occur if we did try produce a 1.2 times wave?