To discover new things, you have to work on ideas that are good but non-obvious; if an idea is obviously good, other people are probably already working on it.
One common way for a good idea to be non-obvious is for it to be hidden in the shadow of some mistaken assumption that people are very attached to.
Every cherished mistaken assumption has a dead zone of unexplored ideas around it.
If you're looking for new ideas, one way to find them is by looking for heresies.