Under forvandlingens lov (Under the Law of Change) or Jo tykkere, jo bedre (The Thicker, the Better) is a Norwegian silent film from 1911. It is the oldest known surviving Norwegian film, and it was directed by Halfdan Nobel Roede. The film has been characterized as an erotic melodrama, and it premiered in Kristiania (now Oslo) on December 4, 1911. The script for the film was written by Peter Lykke-Seest under the pseudonym Søløvenskjold Pedersen.

In 1992, Gunnar Iversen claimed that Roede's lost 1912 silent film I frihetens bur (In the Cage of Freedom) is actually the same film as Under forvandlingens lov.