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
Irrational number number to ratios of continuous magnitude. In his commentary on Book 10 of the "Elements", the Persian mathematician Al-Mahani (d. 874/884) examined and classified quadratic irrationals and cubic irrationals. He provided definitions for rational and irrational magnitudes, which he treated as irrational numbers. He dealt with them freely but explains them in geometric terms as follows: In contrast to Euclid's concept of magnitudes as lines, Al-Mahani considered integers and fractions as rational magnitudes, and square roots and cube roots as irrational magnitudes. He also introduced an arithmetical approach to the concept of irrationality, as he attributes the following to irrational