There are things we cannot see but we know are there. Interstellar ghost hunters in the underground Boulby mine off the Yorkshire coast quietly search for the mysterious dark matter particles that bind the universe together. Follow along on Instagram and Facebook (@secret.passages.pod). Get in touch at https://www.secretpassagespodcast.com/. Researched, written, and produced by E.S. Rodenbiker. Cover art by @game.of.pricks.