I'm not sure if "Quantum Physics" (or "Beyond the Standard Model") is the appropriate place for this question. Please move if necessary. What does "Quaternion Quantum Mechanics" say about the famous double-slit experiment? Does it make the same quantitative prediction as standard [Complex] Quantum Mechanics? Can anyone provide a specific reference? I just checked out my library's copy of Stephen Adler's (1995) "Quaternionic Quantum Mechanics and Quantum Fields"... looking for a statement about this... but I haven't found it yet. I might start tracing back through the various references... Finkelstein-Jauch (1960s), Birkhoff-vonNeumann (1930s), can you suggest any others?