We say that a $T_2$-space $(X,\tau)$ has *homeomorphic open sets* if every non-empty open set $U\subseteq X$ endowed with the subspace topology is homeomorphic to $(X,\tau)$. The rationals with the Euclidean topology are an example of a space with homemorphic open sets, as well as $\{0,1\}^\lambda$, where $\lambda$ is an infinite cardinal and $\{0,1\}$ carries the discrete topology. Is there for every infinite cardinal $\kappa$ a space of cardinality $\kappa$ with homeomorphic open sets? --- **Edit.** Apologies for falsely claiming that $\{0,1\}^\lambda$ is a space with homeomorphic open sets - Joel David Hamkins' comment below gives an argument refuting my claim.