Space Elevator : proposed by Russian Scientist in 1895 . Proposer of this gigantic elevator 36,000 km high was Konstantin Tsiolkovsky. Now, all of sudden we find many companies making claims that such a device is not only viable but also economically feasible.
This gigantic elevator could be used to easily launch rockets, satellites and space vehicles.
The physics behind this idea is brilliant and the challenge is to build it.
It can make space travel much safer, easier and perhaps faster.