Comment on "Inflationary universe: A possible solution to the horizon and flatness problems"

Inflation provides a robust semiclassical mechanism for resolving the horizon and flatness problems once a Friedmann–Lemaître–Robertson–Walker (FLRW) spacetime and scalar-field stress–energy description are assumed. This Comment offers a refined physical interpretation of the domain in which inflationary variables—time, temperature, and energy density—are well-defined. Modern approaches to quantum gravity and emergent spacetime suggest that near the Planck boundary these quantities may not yet have physical meaning, implying that inflation operates within a specific semiclassical regime. Making this interpretive boundary explicit is consistent with Guth’s original discussion and motivates further development of a pre-inflationary physical description.