Full Idea
Cantor's Continuum Hypothesis states that there are no sets which are too large for there to be a one-to-one correspondence between the set and the natural numbers, but too small for there to exist a one-to-one correspondence with the real numbers.
Gist of Idea
Cantor's Continuum Hypothesis says there is a gap between the natural and the real numbers
Source
report of George Cantor (works [1880]) by Leon Horsten - Philosophy of Mathematics §5.1
Book Reference
'Stanford Online Encyclopaedia of Philosophy', ed/tr. Stanford University [plato.stanford.edu], p.22