(FB 1543933688 Timestamp)
THIS IS WHY THERE AREN’T AMAZON DRONES, ROBOTS, AND JETSONS
The problem of batteries that have the energy density of gasoline, so that the weight of the energy and it’s means of conversion to physical movement. Or more simply, power to weight ratio. Rolling wheels, floating water, lift via air, all make use of land, water, air, to discount the cost of defeating gravity (compared to launching a rocket). If you want the distance coverage of an automobile without refueling (4 hrs), or planes (14 hrs), or boats (HP/.6 pr hr), or ships (150 tons per day or 75T for 8 hrs) we still lack the battery technology. And it is this battery technology that is the principle limitation on mechanical evolution. Hence why biological life forms are so vastly more complicated, but vastly more energy efficient. (You, by contrast, cost about the equivalent of a 100w light bulb to live).