Aleph one, written as , is an infinite cardinal number following aleph null ().[1] It is the cardinality (size) of the set of numbers of possible arrangements for all countably infinite sets. Under the continuum hypothesis, it is also the cardinality of the real numbers.[2] Aleph one is followed by aleph two, , even with an infinite amount of time you could simply never list every single element or number in any uncountable set.