Why can current theories not describe events during the Planck era?

Current theories struggle to describe events during the Planck era primarily due to the incompatibility between quantum mechanics and general relativity. The Planck era, which occurred at the very beginning of the universe, is characterized by conditions of extreme energy and density where both quantum effects and gravitational effects are significant. At this stage, conventional physics as we know it breaks down, as the laws governing the large-scale structure of the universe (described by general relativity) conflict with the rules that govern the subatomic particles and forces (described by quantum mechanics).

A successful theory that encompasses both of these frameworks—often referred to as a "theory of quantum gravity"—has yet to be fully developed and accepted within the scientific community. This absence of a unified theoretical framework means that we cannot accurately model or predict the phenomena that would have occurred during the Planck era. Thus, without a coherent understanding of how these two fundamental aspects of physics interact, our ability to discuss events from this epoch remains fundamentally limited.