I think there probably are discoveries that seem obvious or less significant in hindsight that we haven't discovered yet. It will probably have something to do with technology or space travel though. Maybe in 40 years someone will discover some improvement on how we use or store energy or someone will discover something different about the composition of our solar system or something. You can't really know until it happens. Everything looks easier or simpler after it's been done,(reply>), Turns out if you plug an extension cord into itself it makes free energy