 The 8-minute video is narrated by Tony Padilla, a physicist at the University of Nottingham.Padilla begins with and and relates the latter to using a term-by-term subtraction similar to Ramanujan's argument.Numberphile also released a 21-minute version of the video featuring Nottingham physicist Ed Copeland, who describes in more detail how as an Abel sum and as "ζ"(−1).