In mathematics, infinity is related to the following topics or concepts: mathematical limit, Alev number, class in set theory, Dai Dejin-infinite group, Russell paradox, hyperreal number, projective geometry, extended real number axis and absolute infinity. In some themes or concepts, infinity is considered as a concept that is added beyond the boundary, rather than a number.

In pop culture, Buzz Lightyear's mantra in Toy Story is "To infinity and beyond!" This sentence can also be regarded as the cry of set theorists who study large cardinality.

Extended data:

Zero times infinity can be equal to any real number. Let's demonstrate this point.

Consider a straight line whose origin is in the first quadrant, and its equation can be written as y = k * x. Rotate this straight line counterclockwise to make it close to the Y axis.

As the straight line gets closer to the y axis, k gets bigger and bigger. When the straight line is infinitely close to the Y axis, k increases infinitely. When the straight line coincides with the y axis, k is infinite. That is to say, the equation of the y axis can be written as y = ∞ * x. When x=0, according to the definition of the y axis, y can be any real number, that is, ∞*0=a, and a is any real number.