<human>:  Who was the first person to propose the idea of a space elevator?
<bot>: The first person to propose a space elevator was Arthur C. Clarke in the 1950s. He proposed a system of cables attached to the Earth's surface and a counterweight in geosynchronous orbit. The cables would be made of a special material that would allow them to withstand the enormous tensile forces. The counterweight would be made of a special material that would be able to withstand the enormous weight of the cable. The cable would be anchored at both ends to the ground.