A Solomonoff hypothesis can be any computable model that predicts the sequence, including any model that also happens to predict a larger reality if queried in that way. There are always infinitely many such “large world” models that are compatible with the input sequence up to any given point, and all of them are assigned nonzero probability.
It is possible that there may be a simpler model that predicts the same sequence and does not model the existence of any other reality in any meaningful sense, but I suspect that a general universe model plus a fixed-size “you are here” will in a universe with computable rules remain pretty close to optimal.
A Solomonoff hypothesis can be any computable model that predicts the sequence, including any model that also happens to predict a larger reality if queried in that way. There are always infinitely many such “large world” models that are compatible with the input sequence up to any given point, and all of them are assigned nonzero probability.
It is possible that there may be a simpler model that predicts the same sequence and does not model the existence of any other reality in any meaningful sense, but I suspect that a general universe model plus a fixed-size “you are here” will in a universe with computable rules remain pretty close to optimal.