What is a Computer?

Ben Brubaker has a new Quanta essay Does Computer Science Need Computers? Despite the title (and authors generally don't choose their titles), Brubaker's essay really addresses the question as to whether computer science is about computers. He starts with Dijkstra's apocryphal quote "Computer science is no more about computers than astronomy is about telescopes."This is the wrong analogy: computers are not the telescopes, they are the stars. You just have to use a broad definition of computer.The word "computer" goes back to at least 1613. The etymologyLatin com- meant “together.”Putāre meant “to reckon” or “calculate”—and originally “to prune” or “clear up.”English added -er, meaning “someone or something that performs an action.”The word originally meant one who computes, usually referring to a human performing a computational task. Its meaning as a machine didn't come into wide use until the mid-20th century. I start off every undergraduate theory class I teach with the question…