The word infinity comes from the Latin infinitas or "unboundedness." It refers to several distinct concepts which arise in philosophy, mathematics, theology and everyday life. Popular or colloquial usage of the term often does not accord with its more technical meanings.
In Greek philosophy, for example in Anaximander, 'the Boundless' is the origin of all that is. He took the beginning or first principle to be an endless, unlimited primordial mass (apeiron)
In Judeo-Christian theology, for example in the work of theologians such as Duns Scotus, the infinite nature of God invokes a sense of being without constraint, rather than a sense of being unlimited in quantity. In philosophy, infinity can be attributed to space and time, as for instance in Kant's first antinomy. In both theology and philosophy, infinity is explored in articles such as the Ultimate, the Absolute, God, and Zeno's paradoxes.
In mathematics, infinity is relevant to, or the subject matter of, limits, aleph numbers, classes in set theory, Dedekind-infinite sets, large cardinals, Russell's paradox, hyperreal numbers, projective geometry, extended real numbers and the absolute Infinite.
In popular culture, we have Buzz Lightyear's rallying cry, "To infinity - and beyond!", which may also be viewed as the rallying cry of set theorists considering large cardinals.
For a discussion about infinity and the physical universe, see Universe.
The precise origins of the infinity symbol 8 are unclear. One possibility is suggested by the name it is sometimes called - the lemniscate, from the Latin lemniscus, meaning "ribbon." One can imagine walking forever along a simple loop formed from a ribbon.
A popular explanation is that the infinity symbol is derived from the shape of a Möbius strip. Again, one can imagine walking along its surface forever. However, this explanation is improbable, since the symbol had been in use to represent infinity for over two hundred years before August Ferdinand Möbius and Johann Benedict Listing discovered the Möbius strip in 1858.
It is also possible that it is inspired by older religious/alchemical symbolism. For instance, it has been found in Tibetan rock carvings, and the ouroboros, or infinity snake, is often depicted in this shape. In the tarot, the lemniscate represents the balance of forces and is often associated with the magician card.
John Wallis is usually credited with introducing 8 as a symbol for infinity in 1655 in his De sectionibus conicis. One conjecture about why he chose this symbol is that he derived it from a Roman numeral for 1000 that was in turn derived from the Etruscan numeral for 1000, which looked somewhat like CI? and was sometimes used to mean "many." Another conjecture is that he derived it from the Greek letter (omega), the last letter in the Greek alphabet.
