Aleph-1 is the set theory symbol 
for the smallest infinite set larger than 
(Aleph-0), which in turn
is equal to the cardinal number of the set of
countable ordinal numbers.
The continuum hypothesis asserts that 
, where 
is the cardinal number
of the "large" infinite set
of real numbers (called the continuum
in set theory). However, the truth of the continuum
hypothesis depends on the version of set theory
you are using and so is undecidable.
Curiously enough, 
-dimensional
space has the same number of points (
) as one-dimensional space, or any
finite interval of one-dimensional
space (a line segment),
as was first recognized by Georg Cantor.
