"The Everett (?) theory of this section will simply be the pilot-wave
theory without trajectories. Thus instantaneous classical configurations
x are supposed to exist, and to be distributed in the comparison class of
possible worlds with probability |psi|^2. But no pairing of configurations
at different times, as would be effected by the existence of trajectories,
is supposed. And it is pointed out that no such continuity between present
and past configurations is required by experience."
"Now it seems to me that this multiplication of universes is extravagant,
and serves no real purpose in the theory, and can simply be dropped
without repercussions. So I see no reason to insist on this particular
difference between the Everett theory and the pilot-wave theory - where,
although the *wave* is never reduced, only *one* set of values of the
variables x is realized at any instant. Except that the wave is in
configuration space, rather than ordinary three-space, the situation
is the same as in Maxwell-Lorentz electron theory. Nobody ever felt
any discomfort because the field was supposed to exist and propagate
even at points where there was no particle. To have multiplied universes,
to realize all possible configurations of particles, would have seemed
-J.S.Bell, "Quantum Mechanics For Cosmologists", in "Quantum Gravity 2",
eds. C.Isham, R.Penrose, D.Sciama, Oxford U.P., 1981, pp. 652-653.
Here Bell seems to prefer the pilot-wave. According to D.Zeh later he
discarded the pilot-wave (just because it was too similar to the
Everettian approach) and took the GRW model, the 'spontaneous collapse',
which was 'relativistic'.