[loup-vaillant]

Not quite.

Under the many-world interpretation, when you send a photon through a half sieved mirror, the universe splits in one version where the photon goes through, and one universe where the photon doesn't. This is all very deterministic.

What the researcher subjectively observe however is another matter. If the universe splits, so does the researcher. The problem of observing outcomes turns into an anthropy problem: if I split myself in two copies, in which copy am I likeliest to find myself into? I'm not sure making bets about that even makes sense: which copy I find myself into has no bearing in the final state of the universe.

[yters]

Most observers will find themselves in universes with infinite kolmogorov complexity.

[loup-vaillant]

Care to explain why?

[yters]

Most bitstrings are not compressible, so if we look at all the observers across the splitting universes watching a continuous quantum coin flip, most will observe a coin flip sequence that is not compressible, so will observe a constant increase in Kolmogorov complexity.