For non-magnetic solids the two experimental signatures of a non-negligible and decisive interaction between the Debye bosons (sound waves) and the (acoustic) phonons are discussed: 1.) for large thermal energies the dispersion of the mass-less Debye bosons is a weaker than linear function of wave vector, and 2.) for many cubic materials the dispersion of the acoustic phonons along [zeta 0 0] direction follows a perfect sine function of wave vector, which is known to be the dispersion of the linear atomic chain. Only the absolute phonon energies are due to the inter-atomic interactions. It is argued that the sine-function originates in a relatively weak Debye boson-phonon interaction. For a strong Debye boson-phonon interaction, the dispersion of the acoustic phonons assumes initially over a large q-range the linear dispersion of the Debye bosons, followed by an analytical crossover to the sine-function. As a consequence of the boson-controlled wave-vector dependence of the phonons, the temperature dependence of the heat capacity of the phonon system is also determined by the Debye bosons, and exhibits universal power functions of absolute temperature. Quantitative analyses of the dispersion relations of the mass-less Debye bosons (sound waves) of cubic materials along [zeta 0 0] direction show that the dispersion is a linear function of wave vector only for low energies. When all phonon modes are excited, that is, for thermal energies of larger than corresponds to the Debye temperature (Theta(D)), the dispersion of the Debye bosons follows a power function of wave-vector similar to q(x). For the exponent x the rational values of x=0, 1/4, 1/3, 1/2, 2/3 and 3/4 could firmly be established experimentally. The discrete values of x show that there are distinct modes of interaction with the phonons only. Quantitative analyses show that the temperature dependence of the heat capacity can be described accurately over a large temperature range by the expression c(p)=c(0)-B.T-epsilon. The constants c(0) and B are material specific and define the absolute value of the heat capacity. However, for the exponent epsilon the same rational value can be observed for materials with different chemical compositions and lattice structures. The finite temperature range of the c(p)=c(0)-B.T-epsilon function and the rational exponents epsilon are the typical characteristics of a boson determined universal behavior. This universality must, however, be considered as a nonintrinsic dynamic property of the atomistic phonon system, arising from the Debye boson-phonon interaction. Safely identified values for epsilon are epsilon=1, 5/4 and 4/3. The discrete modes of the boson-phonon interaction are essential for the different universality classes of the heat capacity, i.e. for the different exponents e. The fit values for c(0) are generally larger than the theoretical Dulong-Petit value. Universal exponents are identified also in the temperature dependence of the coefficient of the linear thermal expansion, alpha(T). Since the universal power functions in the alpha(T) dependence are functions of absolute temperature and hold for the same thermal energies (temperatures) as the similar to q(x) functions in the dispersion of the Debye bosons, it can be concluded that the Debye bosons determine also the temperature dependence of alpha(T). Our results show that the Debye bosons dominate the dynamics of the atomic lattice of the non-magnetic solids for all temperatures. The atomistic models restricting on the inter-atomic interactions therefore are neither sufficient to explain the phonon dispersion relations nor the detailed temperature dependence of the heat capacity.
