Illuminating the history of the invisible, this podcast interrogates the technologies that allowed Spiritualism to thrive. Beginning at the College for Psychic Studies this particular segment quickly moves into the concrete science of radiowaves, radioactivity, and radio—and their interplay with the imagination. Listen on the BBC.

The image above is from Sebastian Sadowski, who, with his open source web-based design tool, Radiator, aims to “visualise the individual imagination of radio waves.”