I feel this question may be closed as non-constructive, but I'll give it a try.
Suppose a computer simulates a human brain so it passes Turing test. Suppose this brain is given visual, audio and 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 neural network is represented in memory and on disk depends on data structures, computer architecture, endianness, et cetera.
Suppose the last human on Earth dies, but the simulation keeps on running on the computer. If there is no one in the Universe who understands how this particular computer works, nobody 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, nothing prevents other “invisible” brains from existing.
We know that 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 conclusion that if the premise is true, there may be different processes which 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 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.
What if we replace a computer with a man (with a large lifespan) meticulously following the algorithm on the 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?