Blowing-up solutions of Klein–Gordon equations with gauge variant semilinear terms in Friedmann–Lemaître–Robertson–Walker spacetimes under finite speed of propagation

Blowing-up solutions of Klein–Gordon equations with gauge variant semilinear terms are considered in Friedmann–Lemaître–Robertson–Walker spacetimes. Effects of spatial expansion or contraction on the solutions are studied through the scale-function and the curved mass.