Spectrophobia Spectrophobia Spectrophobia (from Latin: "spectrum", n. specio, an appearance, form, image of a thing; an apparition, spectre) or catoptrophobia (from Greek κάτοπτρον "kátoptron", "mirror") is a kind of specific phobia involving a morbid fear of mirrors, sometimes related to the fear of ghosts or the undead. This phobia is distinct from eisoptrophobia, which is the fear of one's own reflection. Generally, an individual that deals with spectrophobia has been traumatized in an event where they believe they have seen or heard apparitions or ghosts. The individual could also become traumatized by horror films, television shows, or by nightmares. This fear
Proof that π is irrational Proof that π is irrational In the 1760's, Johann Heinrich Lambert proved that the number (pi) is irrational: that is, it cannot be expressed as a fraction "a"/"b", where "a" is an integer and "b" is a non-zero integer. In the 19th century, Charles Hermite found a proof that requires no prerequisite knowledge beyond basic calculus. Three simplifications of Hermite's proof are due to Mary Cartwright, Ivan Niven, and Nicolas Bourbaki. Another proof, which is a simplification of Lambert's proof, is due to Miklós Laczkovich. In 1882, Ferdinand von Lindemann proved that is not just irrational, but transcendental as well.