[extropy-chat] Role of MWI and Time Travel

[scerir]

Lee [sorry for this late response!] wrote:
> As for overpopulation [MWI, but backwards in time], 
> I would simply suppose that the version of me 
> who saw the photon go up would smoothly merge 
> into the version of me who saw it go straight; 
> if we branch into separate versions going forward 
> in time, wouldn't it be very natural to merge 
> into a single version going backwards?

Imagine a source of photons, a beam of photons going to 
a beam-splitter, and two detectors (one for each path).
According to the 'collapse' interpretation when a 
detector flashes it means that one photon arrived there 
(while the other detector remains silent). 
According to MWI both detectors flash, but each one 
in its own 'world'.
Now, what if we time-reverse this process? 
According to the 'collapse' interpretation each photon
goes from the detector (that flashed), to the beam-splitter,
and then to the source. So only 50% of photons arrive
at the source (because of the beam-splitter).
According to MWI each photon goes from the detector 
that flashed, to the beam-splitter, and then to the source.
But since we have here 2 worlds (merging) ... 2 x 50% = 100% 
are the photons that arrive at the source. [Unless there is
some big mistake].