Well, the problem is, how do you
measure what the difference in sound is between different types of fingers playing the piano, and how do you generate an algorithm that will accurately model the difference between different hands? That synthesizers will eventually be able to come up with any number of subtly different sounds I don't doubt, but will they accurately model what would happen in the real world? It's much the same issue, I think, with models of the environment:* There are more variables at hand than we can possibly hope to incorporate into any humanly generated model. Until we actually come up with a way to write a computer program to model every aspect the physics of playing a piano, it's unlikely that anyone will be able to come up with a synthesizer recreation that feels right. And it's certainly conceivable that such a thing
could be done eventually, but it begs an important question: Where's the profit in it? I guess it's conceivable that a person might do it entirely for the intellectual rewards, but it seems like it would be an extremely costly project and unless there were some guaranteed way to at least recoup the amount of money required to research the question, it seems unlikely anyone would be willing to pursue it. Unless large numbers of people consciously realise that the complexity of a system involving a real piano and the person who plays it is the reason pianos sound better than synthesizers, there is little chance that research into completely recreating that system will be looked at as a worthwhile use of the time of anyone competent enough to create it.
So yeah, it's not
impossible that one day synthesizers will eventually be as good as the real thing. But it is currently quite unlikely to happen anytime soon. I'm expecting holodeck technology will be halfway to being invented by the time it becomes practical to do so.
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*At this time it is impossible to model an environment as large as the earth. Anyone who says they know what is going to happen to the climate is either overstating their case or just completely full of hooey; the best anyone has is educated guesses. Until we come up with cheap, practical interplanetary/interstellar travel and a workable method of terraforming other planets we'll only have one planet to live on, so therefore we can't afford to take chances about climate change and should start responding as quickly as possible to the threat.</div>