Two concepts of plane waves in anisotropic viscoelastic media are studied. One of these concepts allows for the use of methods based on the theory of complete Bernstein functions. This allows for a deeper study of frequency-domain asymptotics of the attenuation function and timedomain regularity at the wavefronts. A relation between the direction of the energy flux density and the attenuation v...

We describe plane-fronted waves in the Yang-Mills type quadratic metricaffine theory of gravity. The torsion and the nonmetricity are both nontrivial, and they do not belong to the triplet ansatz. PACS: 04.50.+h, 04.30.-w, 04.20.Jb.

It is shown that there are three vacuum and one electrovacuum solutions of diagonal plane waves with M = 0 and constant Maxwell scalars. Namely, these are the single wave, Stoyanov, Babala and Bell-Szekeres solutions. A comparison is made with the planar solutions of Taub.

It is well known that the conformal group of a non-flat vacuum pp-wave is at most 7-dimensional. Here we explicitly determine all solutions with a 7-dimensional group in three particular families of gravitational plane waves. All of them are exact solutions in terms of elementary functions. Furthermore, it turns out that a gravitational plane wave with a 6-dimensional homothety group (larger th...