The square root of -1 is a special number we call i and it is a member of a set of numbers called the imaginary numbers. The imaginary numbers are the set of all numbers that are the square root of negative numbers. - The Math Forum
Q: why bother with such a seemingly frivolous and useless abstraction as i? A: albeit abstract, i is neither frivolous nor useless, as is demonstrated below,
For most human tasks, real numbers (or even rational numbers) offer an adequate description of data. Fractions such as 2/3 and 1/8 are meaningless to a person counting stones, but essential to a person comparing the sizes of different collections of stones.
Negative numbers such as -3 and -5 are meaningless when weighing the mass of an object, but essential when keeping track of monetary debits and credits.
Similarly, imaginary numbers have essential concrete applications in a variety of sciences and related areas such as signal processing, control theory, electromagnetism, quantum mechanics, cartography, and many others. -wikipedia
yet despite their utility, it is the highly abstract nature of imaginary numbers that we tend to struggle with, to resist
for most of us this level of abstraction represents a barrier that separates us from the world of higher mathematics
while for others, as shown in the video below, the abstraction of imaginary numbers is "cool"
and it represents the first real and welcome challenge on the road to a career in mathematics, and more importantly, to a glimpse at truths that few can comprehend
the soundtrack of the above is an excerpt from a BBC Radio 4
5 Numbers podcast
several distinct concepts (usually linked to the idea of "without end") which arise in philosophy, mathematics, and theology.
In mathematics, "infinity" is often used in contexts where it is treated as if it were a number (i.e., it counts or measures things: "an infinite number of terms") but it is a different type of "number" from the real numbers. - wikipedia
now given that infinity is not a real number, as is 2, 6.8, pi, it seems reasonable, if not understandable, that there is no single infinity -
but rather, there are multiple infinities, with some larger than others -
a hierarchy of infinites, as proposed in the video below
the soundtrack of the above is an excerpt from a BBC Radio 4 5 Numbers podcast
many would argue it was the mid-1960s, when such diverse acts as the Beatles and TV bandmaster Lawrence Welk were massively popular in America
despite their popularity, the Beatles and Welk shared very few fans; those who favored one, generally scoffed at others' tastes and life styles
the great majority of those who favored the Beatles were below the age of 30, while those who favored Welk tended to be above (often well above) that generational dividing line
the video below features a '60s radio broadcast of The Jean Shepherd Show
Shepherd's parody reflects how the younger generation viewed Lawrence Welk and his fans