We prove there is a countable dense homogeneous subspace of ℝ of size ℵ₁. The proof involves an absoluteness argument using an extension of the logic obtained by adding predicates for Borel sets.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-fm186-1-5, author = {Ilijas Farah and Michael Hru\v s\'ak and Carlos Azarel Mart\'\i nez Ranero}, title = {A countable dense homogeneous set of reals of size 1}, journal = {Fundamenta Mathematicae}, volume = {185}, year = {2005}, pages = {71-77}, zbl = {1083.54020}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-fm186-1-5} }
Ilijas Farah; Michael Hrušák; Carlos Azarel Martínez Ranero. A countable dense homogeneous set of reals of size ℵ₁. Fundamenta Mathematicae, Tome 185 (2005) pp. 71-77. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-fm186-1-5/