  Collective lattice dynamics determine essential aspects of condensed matter,
such as elastic and thermal properties. These exhibit strong dependence on the
length-scale, reflecting the marked wavevector dependence of lattice
excitations. The extreme ultraviolet transient grating (EUV TG) approach has
demonstrated the potential of accessing a wavevector range corresponding to the
10s of nm length-scale, representing a spatial scale of the highest relevance
for fundamental physics and forefront technology, previously inaccessible by
optical TG and other inelastic scattering methods. In this manuscript we report
on the capabilities of this technique in the context of probing thermoelastic
properties of matter, both in the bulk and at the surface, as well as
discussing future developments and practical considerations.
