Randall Munroe, the NASA roboticist cum artist behind the webcomic xkcd, has a weekly column (what-if.xkcd.com) answering reader’s “What if?” questions about science and technology.

With the clever Munroe as your guide, even the most seemingly absurd speculations lead to valuable insights. We learn why solar cars don’t work via an explanation of why cows don’t photosynthesize, for example. He also plays with pop perceptions of tech fears—he’s sure a robot revolution wouldn’t get anywhere because most don’t work accurately for long and would likely end up stuck against walls.

Munroe’s research rediscovers some wild flights of fancy from the past, as when governments wondered how nuclear weapons might be used in the ocean to create waves extending 300 miles inland. And he also describes amusing examples of government overreach: The Soviets made a machine gun too powerful to work in an airplane, while the U.S. points Hubble-type telescopes from orbit at Earth every day. —Ed Krayewski