Full Idea
Cantor's Continuum Hypothesis was that there is no cardinal number greater than aleph-null but less than the cardinality of the continuum.
Gist of Idea
Continuum Hypothesis: no cardinal greater than aleph-null but less than cardinality of the continuum
Source
report of George Cantor (works [1880]) by Charles Chihara - A Structural Account of Mathematics 05.1
Book Reference
Chihara,Charles: 'A Structural Account of Mathematics' [OUP 2004], p.79
A Reaction
I have no view on this (have you?), but the proposal that there are gaps in the number sequences has to excite all philosophers.