Who knows seventy-three?
Please cite/link your sources, if possible. At some point in the next few days, I will:
Upvote all interesting answers.
Accept the best answer.
Go on to the next number.
The molad (average synodic lunar period) is expressed by Rabban Gamliel (in Rosh Hashanah 25a) as 29 1/2 days, 2/3 of an hour, and 73 chalakim (1 chelek = 3 1/3 seconds).
73 may have been the Sanhedrin of Shamaya and Avtalyon.
Both were converts to Judaism; there's some discussion whether they were full voting members of the Sanhedrin, or only served in an advisory, non-voting capacity (in which case 71 +2 = 73).
73 are the volumes of Schottenstein.
(It fits the beat!)
73 are the verses in Yoel.
73 is the number of answers to shiv'im mi yodeya!