A solid stores energy in the vibrations of the atoms about their equilibrium positions. In the simplest approximation, which Einstein considered, each atom vibrates with the same frequency, ν, in each of three dimensions, so a solid containing N atoms can be thought of as 3N one-dimensional simple harmonic oscillators.
Another somewhat confusing usage is the name "the big bang" for the standard model. It is not appropriate, because it connotes a spatially isolated event, an explosion, that marked the start of everything. ... But the name has a very evident appeal and I expect that people will continue to use it.
I have been working in cosmology for 55 years ... I'm the last man standing, so to speak, from those early days.
I don't think there is a final theory of anything. It's theories all the way down.