Quote from : The Joy of Insight: Passions of a Physicist Book

Through Jung [Pauli] became very interested in various kinds of mysticism, including Jewish mysticism. This led Pauli to develop a friendship with Gershom Scholem, the world's greatest authority in that field and in the Cabala, .... On one occasion Scholem asked me to tell him about unsolved problems in modern physics. .... When I mentioned this number --137-- to Scholem, .... He told me that in Hebrew .... The number corresponding to the word 'cabala' happens to be 137.