The discussion centers on the nature of atomic collisions, suggesting that if only internal atomic motion is considered, all collisions could be viewed as elastic. However, it acknowledges that in quantum mechanics, inelastic scattering, such as the Raman process, can occur. At a macro level, collisions may appear inelastic due to mass merging, but the atomic interactions could still be elastic if particles do not penetrate each other's boundaries. The conversation also touches on the concept of reversible mechanical laws leading to irreversible thermodynamics, highlighting that while collisions may be theoretically reversible, practical outcomes can lead to irreversible changes. Ultimately, the exploration reveals complexities in understanding atomic interactions and their implications for thermodynamics.