Thanos explains to the Silver Surfer that the universe's imbalance is due to the fact that many of its planets are becoming overcrowded and their finite resources are being depleted. Death wants him to correct his imbalance and he plans to accomplish this by killing half of the universe's population. Thanos shows the Surfer this imbalance by bringing him to various planets. Unknown to the Surfer, their travels have set alien viruses upon unprotected species. Instead of trying to stop Thanos right there, the Silver Surfer is forced to return to the planet that they visited in order to save as much of the population as he can.
