Suppose a computer simulates a human brain so that it passes the Turing test. Suppose that this brain is given sensory stimuli that correspond to an experience of being in an Earth-like world. From my understanding, proponents of computationalism suppose that this simulated brain would have qualia.
The neural network, its state, and the program code are stored on a computer, and can only be observed if someone knows how to use this computer. How a neural network is represented in memory and on disk, depends on data structures, computer architecture, endianness, et cetera.
Suppose then that the last human on Earth dies, but the simulation keeps running on the computer. If there is no one in the Universe who understands how this particular computer works, then no one would be able to observe this simulated brain. In other words, this brain would be impossible to “decode”, and yet it would supposedly still experience qualia.
It follows that if this is the case, then nothing prevents other “invisible” brains from existing.
We know that a computer is a computational device, and it is running a complex neural network that corresponds to a human-like mind, but the Universe doesn't “know” it. It is our interpretation of what is happening. I can't stray from the conclusion that if the premise is true, then there may be different processes that isomorphically correspond to computations, some of which may isomorphically correspond to minds, but we won't know it because we don't see this isomorphism.
Why couldn't processes inside the Sun correspond to some computation (albeit in a non-straightforward way) which corresponds to a mind? By that logic, there could be infinitely many minds, all experiencing some sorts of qualia, “encoded” in different ways in all processes in the world.
Conversely, what if we replace a computer with a man (with a large lifespan) meticulously following the algorithm on paper. Would his computations somehow give rise to consciousness within a brain simulated on paper?
This just doesn't make sense to me. Do computationalists believe this, or do they have a counter-argument?