Is there a distinction being made between the quantum computer being impossible, and it being impossible without a future breakthrough in engineering or physics?
If it really is exponentially more difficult to correct for noise as the number of qubits increases, then it will be impossible to build a useful quantum computer. We may not be able to say whether it's impossible after 24 qubits, or after 29, or after 32, etc., but we may be able to know that it's impossible to build anything useful, if someone can rigorously mathematically prove this.
On the other hand if nobody can provide a mathematical proof that it's impossible, it could just be engineering. Then again, "just engineering" doesn't prove a useful quantum computer may require practically impossible configurations (i.e., having to be in the middle of a sphere of lead dozens of miles in radius cooled to near absolute-zero is not necessarily impossible, but isn't something we're going to build anytime soon), or that we simply won't be able to figure out the requisite configurations.
Alternatively, this guy will prove to be wrong and someone will just build a quantum computer with a couple hundred qubits, at which point we may have enough data to observationally draw the curve rather than via math and the simplifications required to make it tractable, and maybe it'll be fine.
On the other hand if nobody can provide a mathematical proof that it's impossible, it could just be engineering. Then again, "just engineering" doesn't prove a useful quantum computer may require practically impossible configurations (i.e., having to be in the middle of a sphere of lead dozens of miles in radius cooled to near absolute-zero is not necessarily impossible, but isn't something we're going to build anytime soon), or that we simply won't be able to figure out the requisite configurations.
Alternatively, this guy will prove to be wrong and someone will just build a quantum computer with a couple hundred qubits, at which point we may have enough data to observationally draw the curve rather than via math and the simplifications required to make it tractable, and maybe it'll be fine.