I mostly agree, but I think there is a risk for a reader of your comment to completely confuse analog computers and scalable digital quantum computers. Analog

I mostly agree, but I think there is a risk for a reader of your comment to completely confuse analog computers and scalable digital quantum computers. Analog computers, like your bathtub accelerator, wind tunnels, ballistic aiming computers, scale models of flood plains, etc, are amazing at one single task (or maybe a few very related tasks), are not Turing complete, and, *by far most importantly*, can not scale as there is a hard insurmountable upper bound on the number of variables they can deal with before noise completely ruins the simulation. Digital computers might be slower (they used to be in the vast majority of cases), but they can scale arbitrarily large, because digital computation permits error correction. That is true about classical digital computers (which have existed for 60ish years after being conceptually predicted 200 years ago) and about digital quantum computers (which do not exist just yet after being predicted 30 years ago). Digital quantum computers also happen to be able to solve efficiently a few important but idiosyncratic problems that classical digital computers can not solve efficiently. I am writing all of this because your complaint, while fairly reasonable when made against any analog computer, is not correct when made against the (proposed) digital quantum computers (like the ones still in development at IBM, Google, PsiQuantum, or many research universities). Lastly, it seems there is some limited resurgence in analog computation lately (classical or quantum, that does not matter), thanks to new technologies (mainly photonics) which provide a significant constant factor improvements in suppressing noise.