I sometimes wonder why the so-called quantum computing field is not considered fringe science by the mainstream media.
It is, in my opinion, not much more credible than perpetual motion or free energy, and less credible than cold fusion...
It is, in my opinion, not much more credible than perpetual motion or free energy, and less credible than cold fusion...
Given that Quantum Computing has yet to deliver on its promise after decades of work and huge investment, I think it is safe to compare the field to other fringe science that once occupied some of the best minds on the planet (like Newton and his obsession with Alchemy).
There's another aspect too: the more generic comments are, the more predictable they are. Since they don't contain much actual information, there's nothing really new to say, which means people repeat the same things over and over. Often they get angry as they do it, since indignation usually fills the vacuum when curiosity is absent.
All of this is the opposite of what we're looking for on HN. What we want: specific, unpredictable, curiosity-gratifying conversation.
https://hn.algolia.com/?dateRange=all&page=0&prefix=true&sor...
https://hn.algolia.com/?dateRange=all&page=0&prefix=false&so...
To me, string theory feels like a fringe science; and irritating one at best.
If quantum computing was not possible, that would mean that everything we thought we knew about physics was hopelessly wrong. Physics would have to be much stranger - we'd have to give up on either locality (i.e. causation being limited by the speed of light), reversibility (closely related to conservation of energy), or nondeterminism in order to make the math work out. There are several papers in the literature that derive quantum mechanics from these or related assumptions (often together with some extra technical detail, that differs between approaches):
https://arxiv.org/abs/quant-ph/0101012 https://arxiv.org/abs/1011.6451 https://arxiv.org/abs/0911.0695
Using rock-solid math and physics I think you can do time travel and speculate about parallel universes, but I don't think we should blindly believe the models.
We should never confuse the map and the territory.
Backwards time travel isn’t possible in general relativity, though, making very mild and physically plausible assumptions about the spacetime. Same in semiclassical quantum gravity.
Speculating about parallel universes is a different story - even if they exist, we can't travel to them, so there is no sense in claiming that we can somehow harness their power. It's a philosophical question, not a physical one. In contrast, the rules of quantum mechanics (when phrased in terms of density matrices, at least) only describe things we can actually measure and observe, and people actually do test every single aspect of the predictions quantum mechanics makes.
This is false. Time travel to the future is possible and proven[0]. Perhaps you are referring to traveling to the past.
[0] https://en.m.wikipedia.org/wiki/Experimental_testing_of_time...
30 years is nothing given how complex the engineering problem is of actually building a working QC. Fusion is much simpler and very well understood and yet it has been more than 50 years since research into fusion power plants has started, and the most optimistic estimates say we'll have the first ever research power plant 30 years from now, if everything goes well (EUfusion's DEMO plant).
There are various applications. Some that you hear about most might be a little overblown (but still maybe not). For example, quantum simulation is an application within the physics field that already makes these systems worthwhile to pursue, without any mention of breaking encryption and the other things mentioned. Quantum logic, i.e. quantum computing on the smallest scale, has been employed to make cutting-edge atomic clocks (which are undeniably a worthwhile pursuit, with countless applications in the real world).
Putting "scaling up quantum computing, the pieces of which have already been demonstrated" in the same sentence as perpetual motion and free energy (known to be in violation of laws of physics) is completely unjustified.
My intuition is that large scale quantum computing is also in violation of laws of physics, but we don't have good models/theory about those yet.
What I am calling for is a reality check on this field.
Pretty much like string theory I am ready to bet it won't go anywhere.
That possibility alone is worth all of the investment in this field.
In contrast, String Theory is just an extension of QM, motivated by nothing except some cool looking math. It doesn't even make any definite predictions (supersimmetry is possible in string theory, but not required, at least not at any particular energy level).
It is already known that many of the most physically important quantum field theories are actually string theories if you rewrite them in different variables (this is called AdS/CFT duality), especially for understanding their large-coupling behavior string theory is the only tool available to analytically understand the theory. So string theory being completely wrong would be as surprising as quantum computing being impossible, for the same reason as you gave for QC. It would indicate something profoundly wrong about something we think we understand well. Its not impossible but the case is much, much more robust than the general internet understands.
And yes, to the extent that it's the same formulae as QM, finding counter-example would be fascinating. But (higher-dimensional) string theory could be wrong with no impact on QM/QFT.
In other words I’m not saying that string theory is (only) a generalization of known correct physics, but that many string theories are equal to (and therefore by definition as physically valid as) physically important quantum field theories. Then there are other string theories that are truly interesting and novel, too.
Additionally, this conjecture is actually experimentally verifiable—you can set up strongly coupled systems in the lab and study the string theory description, and compare the predictions.
Why do we think it is more valid than Alchemy?
More work is needed to turn quantum enhanced optimization into a practical technology. The design of next- generation annealers must facilitate the embedding of problems of practical relevance.
Like fusion, current progress is promising, but practical results lie in the future?