Crank (person)

"Crank" (or kook, crackpot, or quack) is a pejorative term for a person who writes or speaks in an authoritative fashion about a particular subject, often in science, but is alleged to have false or even ludicrous beliefs. Crank can also be used to describe the opinions of these people (see American Heritage Dictionary 2000 - noun definition 3). Usage of the label is often subjective, with proponents of competing theories labeling their opponents cranks, but the term still connotes someone who is well out of mainstream opinion on a matter, as well as connoting a person of dubious mental stability.

Physics, computer science and mathematics

• squaring the circle and trisecting the angle
• producing unified Theories of Everything
• disproving quantum mechanics
• Technological singularity
• disproving Einstein's theory of relativity
• lossless data compression that can always reduce the size of random data
• unbreakable cryptographic ciphers (other than the one-time pad)
• Perpetual motion, probably the earliest example of kookery
• finding a simple proof for Fermat's last theorem, the Goldbach conjecture, etc
• cold fusion
• Disproving Cantor's diagonal argument
• Time Cube as an archetypal example of the work of a science crank
• VMSK and other "ultra narrowband" modulation schemes whose claims violate the Shannon-Hartley theorem
• Alchemy
• Flat Earth Society which asserts that the earth is flat.
• Modern geocentrism