Yes, which is why there’s a difference between the computation (the map) and the physical operation (the territory). A computer has an undisputed physical reality and performed undisputed physical acts (the territory). These can be understood as performing computations. (a map). The two are different, and therefore the computation is different from the phsycail operation.
It is possible to have more than one map of a given territory. You can have a street map, but also a topographical map. Similarly, a given physical operation can be understood in more than one way, as performing more than one computation. One class of computation is simulation. The physical world (the whole world) can be understood as performing a simulation of a physical world. Whereas only a small part of the laptop is directly involved in spell-checking a text document, the whole laptop, in fact the whole physical world, is directly involved in the simulation.
The computation “spell checking a text” is different from the physical operation. This is easy to prove. For example, had the text been stored in a different place in physical memory then the same computation (“spell checking a text”) could still be performed. There need not be any difference in the computation—for example, the resulting corrected text might be exactly the same regardless of where in memory it is stored. But what about the simulation? If so much as one molecule were removed from the laptop, then the simulation would be a different simulation. We easily proved that the computation “spell checking a text” is different from the physical operation, but we were unable to extend this to proving that the computation “simulating a physical world” is different from the physical operation.
It is possible to have more than one map of a given territory. You can have a street map, but also a topographical map. Similarly, a given physical operation can be understood in more than one way, as performing more than one computation. One class of computation is simulation. The physical world (the whole world) can be understood as performing a simulation of a physical world. Whereas only a small part of the laptop is directly involved in spell-checking a text document, the whole laptop, in fact the whole physical world, is directly involved in the simulation.
The computation “spell checking a text” is different from the physical operation. This is easy to prove. For example, had the text been stored in a different place in physical memory then the same computation (“spell checking a text”) could still be performed. There need not be any difference in the computation—for example, the resulting corrected text might be exactly the same regardless of where in memory it is stored. But what about the simulation? If so much as one molecule were removed from the laptop, then the simulation would be a different simulation. We easily proved that the computation “spell checking a text” is different from the physical operation, but we were unable to extend this to proving that the computation “simulating a physical world” is different from the physical operation.