I see the evidence, and I see the conclusion, but there's a lot of ellipses between the evidence and the conclusion.
Do quantum computing folks really think that we are borrowing capacity from other universes for these calculations?
I have no idea who put it there, but I can assure you the actual paper contains no such nonsense.
I would have thought whoever writes the google tech blogs is more competent than bottom tier science journalists. But in this case I think it is more reasonable to assume malice, as the post is authored by the Google Quantum AI Lead, and makes more sense as hype-boosting buzzword bullshit than as an honest misunderstanding that was not caught during editing.
No sign of a Heisenberg cut has been observed so far, even as experiments involving entanglement of larger and larger molecules are performed, which makes objective-collapse theories hard to consider seriously.
Bohmian theories are nice, but require awkward adjustments to reconcile them with relativity. But more importantly, they are philosophically uneconomical, requiring many unobservable — even theoretically — entities [0].
That leaves either many-worlds or a quantum logic/quantum Bayesian interpretations as serious contenders [1]. These interpretations aren't crank fringe nonsense. They are almost inevitable outcomes of seriously considering the implications of the theory.
I will say that personally, I find many-worlds to focus excessively on the Schrödinger-picture pure state formulation of quantum mechanics. (At least to the level that I understood it — I expect there is literature on the connection with algebraic formulations, but I haven't taken the time to understand it.) So I would lean towards quantum logic–type interpretations myself.
The point of this comment was to say that many-worlds (or "multiverses", though I dislike the term) isn't nonsense. But it also isn't exactly the kind of sci-fi thing non-physicists might picture. Given how easy it is to misinterpret the term, however, I must agree with you that a self-aware science communicator would think twice about whether the term should be included, and that there may be not-so-scrupulous intentions at play here.
Quick edit: I realise the comment I've written is very technical. I'm happy to try to answer any questions. I should preface it by stating that I'm not a professional in the field, but I studied quantum information theory at a Masters level, and always found the philosophical questions of interest.
---
[0] Many people seem to believe that many-worlds also postulates the existence of unobservable parallel universes, but this isn't true. We observe the interaction of these universe's every time we observe quantum interference.
While we're here, we can clear up the misconception about "branching" — there is no branching in many-worlds, just the coherent evolution of the universal wave function. The many worlds are projections out of that wave function. They don't discretely separate from one another, either — it depends on your choice of basis. That choice is where decoherence comes in.
[1] And of course, there is the Copenhagen "interpretation" — preferred among physicists who would rather not think about philosophy. (A respectable choice.)
As a side note, there is still a huge gap between the largest system we've ever observed in a superposition and the smallest system we've ever observed to behave only classically. So there is still a lot of room for objective collapse theories, even though that space has shrunk by some orders of magnitude since it was first proposed. Of course, objective collapse has other, much bigger, problems, such as being incompatible with Bell's inequalities.
Edit: I'd also note some things about MWI. First, there are many versions of it, some historical, some current. Some versions, at least older ones, absolutely did involve explicit branching. And the ones that don't have a big problem still with explaining why, out of the many ways to choose the basis vectors for a measurement, we always end up with the same classical measurables in every experiment we perform on the world at large. Especially given that we know we can measure quantum systems in another other basis if we want to. It also ultimately doesn't answer the question of why we need the Born rule at all, it still postulates that an observer only has access to one possible value of the wave function and not to all at once. And of course, the problem of defining probabilities in a world where everything happens with probability 1 is another philosophically thorny issue, especially when you need the probabilities to match the amplitude of the wave function.
So the MWI is nice, and it did spawn a very useful and measurable observation, decoherence. But it's far from a single, satisfying, complete, self-consistent account of the world.
But it is not true for MWI: MWI was designed from the ground up as an interpretation of the mathematics and experimental results of quantum mechanics. It is designed specifically to not match all of the predictions of quantum mechanics, and to not make any new predictions. Other interpretations are also designed in the same way.
So, if the people creating these interpretations succeeded in their goals when making them, then they will never be experimentally verifiable.
However, I also think there is a tendency among well-educated people in physics to dismiss philosophical questions out of hand. It's fair enough when the point is "let's focus on the physics as it's hard enough", but questions of interpretation have merit in their own right.
> While we're here, we can clear up the misconception about "branching" — there is no branching in many-worlds, just the coherent evolution of the universal wave function. The many worlds are projections out of that wave function.
I've never heard about quantum logic before. The "Bayesian" part makes sense because of how it treats the statistics, but the logic? Is that what quantum computer scientists do with their quantum circuits, or is it an actual interpretation?
If you are okay with a single universe coming to existence out of nothing you should be able to handle parallel universes as well just fine.
Also your comment does not have any useful information. You assumed hype as the reason why they mentioned parallel computing. It's just a bias you have on looking at world. Hype does helps explain a lot of things. So it can be tempting to use it as a placeholder for anything that you don't accept based on your current set of beliefs.
I didn't "assume" hype, I hypothesized it based on the evidence before me: There is nothing in Google's paper that deals with interpretations of quantum mechanics. This only appears in the blog post, with no evidence given. And there is nothing google is doing with it's quantum chip that would discriminate between interpretations of QM, so it is simply false that "It lends credence to ... parallel universes" over another interpretation.
I can handle it, sure, and the idea of the multiverse is attractive to me from a philosophical standpoint.
But we have no evidence that there are any other universes out there, while we do have plenty of evidence that our own exists. Just because one of something exists, it doesn't automatically follow that there are others.
We have evidence for this universe though.
I can get on board with that: that there may be other, distinct universes, but I do not understand how this would lead to the suggestion they would be necessarily linked together with quantum effects.
Let me add a recommendation for David Wallace's book The Emergent Multiverse - a highly persuasive account of 'quantum theory according to the Everett Interpretation'. Aside from the technical chapters, much of it is comprehensible to non-physicists. It seems that adherents to MW do 'not know how to refute an incredulous stare'. (From a quotation)
People call it "many worlds" because we can interact only with a tiny fraction of the wavefunction at a time, i.e. other "branches" which are practically out of reach might be considered "parallel universes".
But it would be more correct to say that it's just one universe which is much more complex than what it looks like to our eyes. Quantum computers are able to tap into this complexity. They make a more complete use of the universe we are in.
A poll of 72 "leading quantum cosmologists and other quantum field theorists" conducted before 1991 by L. David Raub showed 58% agreement with "Yes, I think MWI is true".[85]
Max Tegmark reports the result of a "highly unscientific" poll taken at a 1997 quantum mechanics workshop. According to Tegmark, "The many worlds interpretation (MWI) scored second, comfortably ahead of the consistent histories and Bohm interpretations."[86]
In response to Sean M. Carroll's statement "As crazy as it sounds, most working physicists buy into the many-worlds theory",[87] Michael Nielsen counters: "at a quantum computing conference at Cambridge in 1998, a many-worlder surveyed the audience of approximately 200 people... Many-worlds did just fine, garnering support on a level comparable to, but somewhat below, Copenhagen and decoherence." But Nielsen notes that it seemed most attendees found it to be a waste of time: Peres "got a huge and sustained round of applause…when he got up at the end of the polling and asked 'And who here believes the laws of physics are decided by a democratic vote?'"[88]
A 2005 poll of fewer than 40 students and researchers taken after a course on the Interpretation of Quantum Mechanics at the Institute for Quantum Computing University of Waterloo found "Many Worlds (and decoherence)" to be the least favored.[89]
A 2011 poll of 33 participants at an Austrian conference on quantum foundations found 6 endorsed MWI, 8 "Information-based/information-theoretical", and 14 Copenhagen;[90] the authors remark that MWI received a similar percentage of votes as in Tegmark's 1997 poll.[90]
[1] https://en.wikipedia.org/wiki/Many-worlds_interpretation#Pol...
Reminds me of the Aorist Rods from Hitchhikers' Guide to the Galaxy.
Science is about coming up with the best explanations irrespective of whether or not a large chunk does not believe it.
And best explanations are the ones that is hard to vary. Not the one that is most widely accepted or easy to accept based on the current world view.
No, but as non-experts in a given field, the best information we have to go on is the consensus among scientists who are experts in the field.
Certainly this isn't a perfect metric, and consensus-smashing evidence sometimes comes to light, but unless and until that happens, we should assume that the people who study this sort of thing as their life's work are probably more correct than we are.
Ideally this would be true, but funding agencies are already preloaded with implicit asssumptions what constitutes a scientific progress.
MWI has not led to any verifiably-correct predictions, has it? At least not any that other interpretations can also predict, and have other, better properties.
Or is this one of those rhetorical questions?
It could be that we are borrowing qbit processing power from Russel's quantum teapot.
or you mean specifically the parallel computation view?
Unsure about those working on quantum foundations, but I think the absence of consensus is enough to claim any view as absolutely not the view.
i think if you were to ask people to make a real metaphysical speculation, majority might be partial to everett - especially if they felt confident the results were anonymous
I believe the vast majority of researchers in quantum computing* spend almost no time on metaphysical speculation,
*Well, those on the "practical side" that thinks about algorithms and engineering quantum systems like the Google Quantum AI team and others. Not the computer science theorists knee-deep in quantum computational complexity proofs nor physics theorists working on foundations of quantum mechanics. But these last two categories are outnumbered by the "practical" side.
The success on the random (quantum) circuit problem is really a valdiation of Feynman's idea, not Deutsch: classical computers need 2^n bits to simulate n qubits, so we will need quantum computers to efficiently simulate quantum phenomena.
Maybe A wasn't the most efficient algorithm for this universe to begin with?
That's in line with a religious belief. One camp believes one thing, other believes something else, others refuse to participate and say "shut up and calculate". Nothing wrong with religious beliefs of course, it's just important to know that is what it is.
A simple counterexample is superdeterminism, in which the different measurement outcomes are an illusion and instead there is always a single pre-determined measurement outcome. Note that this does not violate Bell's inequality for hidden variable theories of quantum mechanics, as Bell's inequality only applies to hidden variables uncorrelated to the choice of measurement: in superdeterminism, both are predetermined so perfectly correlated.
Just to be clear, where in the Schrödinger equation (iħψ̇ = Hψ) is the "multiverse"?
Copenhagen interpretation is just "easier" (like oops all our calculations about the univers don't seemt to fit, lets invent "dark matter") when the correct explanations makes any real world calculation practically impossible (thus ending most of physics further study) as any atom depends on every other atom at any time.
Doesn't this also mean that other universes have civilizations that could potentially borrow capacity from our universe, and if so, what would that look like?
Tangentially related, but there's a great Asimov book about this called The Gods Themselves (fiction).
That being said, I think the two most commonly preferred interpretations of quantum mechanics among physicists are 'Many Worlds' and 'I try not to think about it too hard.'
I don't know much about multiverse, but we need something external to explain the magic we uncover.
Energy and quantum mechanics are really cool but dense to get into. Like Planck, I suspect there's a link between consciousness and matter. I also think our energy doesn't cease to exist when our human carcass expires.
I used to love Popular Science magazine in middle school, but by high school I had noticed how much it's claims were hyperbole and outright nonsense. I can't fathom how or why, but most people blame the scientists for it.
Puffery is not a victimless crime.
"Do quantum computing folks really think that we are borrowing capacity from other universes for these calculations?"
In this context, your opinion and Deutsch's opinion don't matter. The question is about whether the idea is common in the field or not.
Quantum mechanics is a tool to calculate observable values, and this tool works very successfully without needing to make strong assumptions about the nature of the universe.
If it's not, what would be your explanation for this significant improvement then?