The (in)famous "Schrödinger's Cat" thought-experiment highlights an (apparent) paradox of quantum mechanics. A cat is placed in a box, and an apparatus containing an unstable atomic nucleus is connected to machinery that will kill the cat if the nucleus decays. If nobody is observing the cat, is it alive, or dead, or in some nonclassical superposition of quantum states? Weighty tomes have been written about the question.

But equally important, and not yet discussed in the physics literature, are the following found in a lost notebook of Erwin Schrödinger that I purchased recently via Internet auction (so it must be genuine):

• Schrödinger's Catamaran — does it float, or sink? Try it and see ...
• Schrödinger's Catalog — full of wonderful items, but there's no way to tell what's out-of-stock until you call in your order ...
• Schrödinger's Catechism — maybe it explains holy articles of faith, or maybe it's full of rankest heresy. Nobody can know until they've knocked on the Pearly Gates, at which point it's too late ...

Other pages discuss Schrödinger's Cataracts, Schrödinger's Caterpillar, Schrödinger's Cathode, Schrödinger's Cattle, etc. Unfortunately the notebook itself is almost impossible to understand; whenever I try to look at a page, the letters swim about and rearrange themselves faster and faster the harder I work to read them ...

_{(with apologies to Mark Twain's "A Cat Tale"; cf. Quantum Nondemolition (2000-02-05), No Concepts at All (2001-02-22), Correspondence Principle (2003-03-04), Many Worlds (2006-08-17), ...) - ^z - 2008-01-26}

(correlates: ManyWorldsDemystified, Asimov on Zoology, ExcrementalTypo, ...)