If a human is ultimately made up of nothing more than particles obeying the laws of physics, it would be in principle possible to simulate one on paper. Completely impractical, but the same is true of simulating Claude by hand (presuming Anthropic doesn't have some kind of insane secret efficiency breakthrough which allows many orders of magnitude fewer flops to run Claude than other models, which they're cleverly disguising by buying billions of dollars of compute they don't need).
The physics argument assumes consciousness is computable. We don't know that. Maybe it requires specific substrates, continuous processes, quantum effects that aren't classically simulable. We genuinely don't know. With LLMs we have certainty it's computation because we built it. With brains we have an open question.
