How do we know that this assumption is incorrect? Well, classical theories may lead to anomalies that imply that no quantum theory with a given classical limit may exist. More generally, quantization of classical theories often leads to non-renormalizable theories which are no good as a starting point for predictions.

These insights are robust conclusions of a paramount section of theoretical physics, the renormalization group, a theoretical machinery that is important both in high-energy physics as well as condensed-matter physics and other fields.

— Loop quantum cosmology

— Lubos Motl

2011.01.12 Wednesday ACHK