The notion of complex-valued or even quaternionic or octonionic
probabilities has been considered; see
for some pointers into the literature.
-- Ben Goertzel
> -----Original Message-----
> From: scerir [mailto:[EMAIL PROTECTED]
> Sent: Friday, January 23, 2004 9:23 AM
> To: [EMAIL PROTECTED]
> Subject: Re: probabilities & measures & computable universes
> Are probabilities always and necessarily positive-definite?
> I'm asking this because there is a thread, started by Dirac
> and Feynman, saying the only difference between the classical
> and quantum cases is that in the former we assume the probabilities
> are positive-definite.
> Thus, speaking of MWI, we could also ask: what is the joint
> probability of finding ourselves in a universe alpha and of
> finding ourselves in a universe beta, which is 180 degrees
> out of phase with the first one (whatever that could mean)?