Discuss the significance of string theory's landscape problem in contemporary physics. How does the multiplicity of possible solutions impact the predictability and testability of the theory?

String theory proposes a vast number of potential solutions, each corresponding to a different universe with its own set of physical laws. This “landscape” of solutions challenges the theory’s predictability because it makes it difficult to determine why our particular set of physical constants and laws would be favored. Critics argue that this undermines the scientific testability of string theory, whereas proponents suggest that it represents a rich framework for understanding possible universes, contingent on further theoretical and experimental advances.