Back in the late 1960s and early 1970s, proponents of the hypothesis that human civilization had been jump-started by extraterrestrial visitors pointed to the Egyptian pyramids as persuasive evidence. The ancient Egyptians could not have moved those massive multiton stone blocks with just muscle power, they argued, and suggested that alien anti-gravity technology was a more, uh, plausible explanation [source: Shermer].
Fortunately, in 2014, University of Amsterdam physicists materialized to rescue us from paperback pseudoscience. By analyzing an ancient tomb drawing, they figured out that a large team of workers could have hauled the giant stone blocks on a sled, and poured water on the sand in their path to reduce the friction and make it possible to drag the blocks to the pyramid [sources: Chowdury, Fall, et al.]. Other researchers also have suggested that the Egyptians used clay as a lubricant, and it may be that they used more than one method [source: Chowdury].