The continuum hypothesis says $2^{\aleph_0} = \aleph_1$, right?
The cardinal of $[0,1]$ is $2^{\aleph_0}$.
By definition, $\aleph_1$ is the cardinal of the least uncountable ordinal. That is, a well-ordered set that is uncountable, and each initial segement is countable.
The last step: if two sets have the same cardinal, then there is a one-to-one mapping from one onto the other.
The continuum hypothesis says $2^{\aleph_0} = \aleph_1$, right?
The cardinal of $[0,1]$ is $2^{\aleph_0}$.
By definition, $\aleph_1$ is the cardinal of the least uncountable ordinal. That is, a well-ordered set that is uncountable, and each initial segement is countable.
The last step: if two sets have the same cardinal, then there is a one-to-one mapping from one onto the other.