> With quantum computing there are also no real signs that a quantum computer will beat a "classical" computer at anything any time soon. It always was and still is very difficult to get quantum systems to scale and you need a large enough system to make a difference and it may be impossible to do so. Again a lot of this is more of an engineering problem though admittedly the line between physics and engineering can be blurry since it's not always clear whether something can't be done because you've reached a fundamental limitation vs. having a clever enough design.
The mentioning of quantum computers is very interesting in the following sense: If one were able to build a sufficiently large quantum computer, this would provide strong evidence that the (at the moment rather hypothetical) theory whether quantum mechanics is rather an emergent phenomen by a deterministic process (cellular automaton)
> https://arxiv.org/abs/1405.1548
which the Nobel laureate Gerard 't Hooft worked on for the last years is probably wrong. To quote p. 79-80:
"Such scaled classical computers can of course not be built, so that this quantum computer
will still be allowed to perform computational miracles, but factoring a number with
millions of digits into its prime factors will not be possible – unless fundamentally improved
classical algorithms turn out to exist. If engineers ever succeed in making such quantum
computers, it seems to me that the CAT is falsified; no classical theory can explain
quantum mechanics."
On the other hand, if we seriously get into trouble building a sufficiently large quantum computer (despite our best efforts), this would at least to me provide evidence that 't Hooft is on something - since that this is a prediction that his Cellular Automaton Interpretation of Quantum Mechanics provides.
