WASHINGTON — It used to be only Superman who could see through concrete walls, but an exhibition at the National Building Museum shows that mere mortals can do it too. Called “Liquid Stone,” the show ...

Translucency, at its essence, is an optical property that enables the total or partial passage of light through materials, without providing a clear view of the objects behind them. Despite its ...

WASHINGTON — It used to be only Superman who could see through concrete walls, but an exhibit at the National Building Museum shows mere mortals can do it too. Called ‘‘Liquid Stone,'' the show ...