One of the signature moments of the Watergate scandal was the discovery of an 18.5-minute gap on a White House recording of a meeting between President Richard Nixon (he of a surprisingly good policy idea) and a key aide.
I had always thought this gap was just made up of silence. But now I know better.
Those 18.5 minutes of blank tape are not really blank, as explained by Sophie Scott in a fascinating edition of the Boring Talks podcast.
You can listen to it online here.