My New York Times essay on quantum computing
I have a special treat for those commenters who consider me an incorrigible publicity-hound: an essay I was invited to write for the New York Times Science section, entitled Quantum Computing Promises New Insights, Not Just Supermachines. (My original title was “The Real Reasons to Study Quantum Computing.”) This piece is part of a collection of essays on “the future of computing,” which include one on self-driving cars by Sebastian Thrun, one on online learning by Daphne Koller, and other interesting stuff (the full list is here).
In writing my essay, the basic constraints were:
(a) I’d been given a rare opportunity to challenge at least ten popular misconceptions about quantum computing, and would kick myself for years if I didn’t hit all of them,
(b) I couldn’t presuppose the reader had heard of quantum computing, and
(c) I had 1200 words.
Satisfying these constraints was harder than it looked, and I benefited greatly from the feedback of friends and colleagues, as well as the enormously helpful Times staff. I did get one request that floored me: namely, to remove all the material about “interference” and “amplitudes” (too technical), and replace it by something ordinary people could better relate to—like, say, a description of how a quantum computer would work by trying every possible answer in parallel. Eventually, though, the Gray Lady and I found a compromise that everyone liked (and that actually improved the piece): namely, I’d first summarize the usual “try all answers in parallel” view, and then explain why it was wrong, bringing in the minus signs and Speaking Truth to Parallelism.
To accompany the essay, I also did a short podcast interview about quantum computing with the Times‘ David Corcoran. (My part starts around 8:20.) Overall, I’m happy with the interview, but be warned: when Corcoran asks me what quantum computers’ potential is, I start talking about the “try all answers in parallel” misconception—and then they cut to the next question before I get to the part about its being a misconception! I need to get better at delivering soundbites…
One final comment: in case you’re wondering, those black spots on the Times‘ cartoon of me seem to be artifacts of whatever photo-editing software they used. They’re not shrapnel wounds or disfiguring acne.
Follow
Comment #1 December 5th, 2011 at 10:10 pm
They chose the right hound for the job. Very nice work, Scott.
Comment #2 December 5th, 2011 at 10:35 pm
Nice article but I am confused about this paragraph:
“For example, the mere possibility of quantum computers has all but overthrown a conception of the universe that scientists like Stephen Wolfram have championed. That conception holds that, as in the “Matrix” movies, the universe itself is basically a giant computer, twiddling an array of 1’s and 0’s in essentially the same way any desktop PC does.”
A quantum universe or a classical universe are both computable aren’t they? It’s just that the quantum universe is exponentially “bigger”. In principle, you could have a classical computer just chug away painfully slowly and simulate the quantum universe, no? There is nothing in the “Matrix” universe that says the computation must be efficient is there? There are still just a countable number of possible quantum universes right?
Comment #3 December 5th, 2011 at 10:50 pm
About quantum error correction, you say:
“But experimentalists seem nowhere near that critical level yet.”
I’m not so sure about that
Comment #4 December 5th, 2011 at 10:51 pm
Nicely done! I’m glad they asked someone who would insist on including at least some mention of the minus signs, which is sort of a litmus test for whether a popular article is talking about quantum computation correctly. As metaphors for abstruse concepts go, “soufflé” and “choreograph” were nice touches.
Comment #5 December 5th, 2011 at 10:59 pm
Carson #2: Yes, as the tagline of my blog says, quantum computers can be simulated classically but with exponential slowdown.
What we learn from quantum computing is that, if both quantum mechanics and the prevailing conjectures in complexity theory are valid, then the physical universe can’t be feasibly simulated by a computer that “twiddles an array of 1’s and 0’s in essentially the same way any desktop PC does.”
(That last clause was meant to indicate that I was talking about efficient simulation by conventional computers — i.e., the Extended Church-Turing Thesis, or what Wikipedia calls the Feasibility Thesis. I wish I knew how to put the point more clearly within the constraints of this article, since you’re right that it might be misinterpreted!)
For what it’s worth, Stephen Wolfram, Ed Fredkin, and other believers in “digital physics,” have been very explicit in saying that they think the universe is a classical cellular automaton—basically, a three-dimensional array of pixels—and that their view would preclude exponential speedups from quantum computation. (Wolfram believes that quantum mechanics is wrong, whereas Fredkin believes that quantum mechanics can be efficiently simulated classically.) So, these viewpoints would indeed be ruled out under the assumptions I mentioned above.
A last remark: the Matrix movies aren’t very clear about what type of computer is being used, other than that it’s powered by human bodies! But since they never mention anything about quantum computing, and since the simulation clearly isn’t astronomically slow, it seems reasonable to assume that Keanu Reeves was trapped in some sort of classical simulation. So maybe he could’ve caused the simulation to crash by building a quantum computer and trying to run Shor’s factoring algorithm! For the version where Keanu is trapped in a quantum computation, we might need to wait for the followup trilogy, “The Unitary Matrix” (har, har).
Comment #6 December 5th, 2011 at 11:07 pm
rrtucci #3: Obviously, our distance to the threshold is something I’d love to be proven wrong about! But while the Yale group’s recent result looks really exciting, there must be a catch somewhere, or else we’d have scalable QCs already. So, what’s the catch?
Comment #7 December 5th, 2011 at 11:14 pm
The catch is there is no catch.
Comment #8 December 6th, 2011 at 12:45 am
The Boston Globe quotes you saying “It’s entirely conceivable that quantum computing is impossible for some fundamental reason.” But the NY Times article does not say this, and suggests that just politics and economics are holding quantum computers back.
Comment #9 December 6th, 2011 at 12:59 am
Nice essay Scott, but how could we know our simulation is not astronomically slow?
I’m curious to see if Greg Egan will comment this one 😉
Comment #10 December 6th, 2011 at 1:20 am
Nice article.
By contrast, here is an entertainingly terrible summary of our field:
http://future-observatory.blogspot.com/2011/09/quantum-computing-real-researchers-have.html
Comment #11 December 6th, 2011 at 2:13 am
I forgot that I had a real question. 🙂
What is the classical cryptosystem whose analysis involves quantum computing? Are you talking about quantum-resistant crypto?
Comment #12 December 6th, 2011 at 2:23 am
Right as I wrote that, I was watching a video of Umesh’s 2010 QIP talk. I guess you were referring to this result?.
Comment #13 December 6th, 2011 at 3:25 am
It is a very good article. I think you may be too pessimistic when you say that “experimentalists seem nowhere near that critical level yet.” Over the last several years, the coherence times of superconducting qubits have followed a steady exponential curve. The catches right now are that experiments have not yet demonstrated multi-qubit gates with error rates close to the limits of the decoherence time, and measurements are too slow. Scaling is never automatic, either. Of course it is better to be pessimistic than overly optimistic, but I’m not sure you captured how exciting the experiments of the last few years have been.
It is also strange to talk about the influence of quantum computing on “chemistry and physics.” Quantum computing is physics. Quantum computing started with Feynman, and most of the theoretical ideas are still coming from physicists. It has already had a huge influence on experimental physics. Qubits are everywhere these days, and coupling together different kinds of qubits allows for completely new physics. The impact on computer science has been considerably less.
Comment #14 December 6th, 2011 at 3:50 am
I think this came out very well, Scott, including the technical paragraph. Congratulations, and thank you for doing this.
At which point did you abandon the ambition to challenge ten popular misconceptions about quantum computing for the (equally important) quest saying something snarky about Wolfram? The moral algebra seems to be that 9 misconceptions equal one dig at NKS. (Not that I mind.)
Comment #15 December 6th, 2011 at 6:11 am
Regarding Fredkin, a steadily expanding section of my BibTeX database is “physics beyond the standard state-space” (keyword PBSSS), which is associated to dynamical trajectories on state spaces that manifest quantum interference yet are non-Hilbert. Fredkin’s on line monograph Digital Philosophy receives this keyword.
The ideal PBSSS article would be mathematically natural, solidly grounded in physical experiment, and immediately useful in enterprise applications — regrettably no such “triple-threat” article PBSSS articles exist at present.
A notable trend in the PBSSS literature is an increasing concern with localizability; this concern is shared by mathematicians, physicists, and engineers alike. To appreciate the origins of this shared concern it is helpful to reflect that practical quantum systems engineering problems associated to cavity QED (for example) are intimately bound-up with the fundamental physics of localization and causality. My experience has been Daniel Terno’s articles commonly include thought-provoking reflections on this general theme (see arXiv:gr-qc/0505068 for example).
In recent years there has been a notable outburst of creative activity in the application-centric sector of the PBSSS literature. If we are lucky, this is a sign that history is repeating itself, since in the early 20th century the seminal practical applications of quantum theory were conceived before quantum theory was formalized. Perhaps this is happening again.
Therefore, to extend the conclusion of your NYT essay, it may be the case that “There’s no need to wait for quantum computing or for a better quantum theory either“, because just as was true during the development of quantum mechanics early 20th century, it would suffice to have a deeper mathematical and physical understanding of why the computational recipes that we already have, work as well as they already do. In this respect the pay-off from fundamental research in quantum computing already has great value.
Comment #16 December 6th, 2011 at 6:31 am
As one who is slightly below Shaw’s Intelligent Layman, I have always relied on the kindness of scientific strangers to give me the Reader’s Digest guide to quantum mechanics, holographic universes, Dirac’s Unitary Hypothesis, fractals, etc. But, I have yet to truly understand the quantum. I will read this blog hoping it explicates it for the grammar school mind. I, too, did not feel your Times article met your own demands. But that’s a good thing.
Comment #17 December 6th, 2011 at 8:12 am
Oddly, I had an interesting discussion about the Matrix recently. In the movie, one of the interesting aspects is that while the actors are out of the Matrix, they can only view the code directly and not the actual images being generated.
If one follows the quantum analogy a little, what one could think of is that the code being viewed are actual the lists of quantum numbers (aka variables) associated with the CSCO basis for each state function for each object. The particular state that is observed is then displayed as finite values in the code.
In this setup the state functions of the various objects are actually part of the image processing system. This is can be visualized by thinking of the quantum hydrogen model. The state function governs the particular continuous spatial probability function that determines where the observation will occur. The observation, once made, is recorded in the code representation that one sees outside the matrix.
In this sense, the code being viewed is merely the recording of states that have been computed by the image processors of the Matrix, which can not be viewed unless one is actually inside the matrix, since one needs to be an active participant in the calculation in order to see the images.
What this implies is that the brains of humans are acting as the image processing hardware, which takes the information of the previously recorded state observations and calculates the images of the system.
In this construct, consciousness is viewed as being related to the classical computers governed by classical physics (EM) and thus viewed as software that interacts inside (or on top of) the underlying quantum world, which is why agents can move from human to human in the matrix…they are merely software and not hardware.
I doubt this is what people had in mind when writing the matrix, but I think it does provide an interesting way of thinking about the problem.
Comment #18 December 6th, 2011 at 8:15 am
Roger #8:
The Boston Globe quotes you saying “It’s entirely conceivable that quantum computing is impossible for some fundamental reason.” But the NY Times article does not say this, and suggests that just politics and economics are holding quantum computers back.
The issue is that, for quantum computing to be fundamentally impossible, quantum mechanics as currently understood would have to wrong (i.e., even if the theory were “formally” correct, there would have to be some amazing new principle on top of it that reduced the effective size of the state space by an exponential amount).
I agree that this is conceivable, but I also regard it as extremely unlikely—certainly much less likely than the (relatively!) “boring” outcome of QM being vindicated and scalable QCs indeed being possible.
I did mention the possibility of QM being wrong in my Times article, in the following sentence:
Indeed, the only ways to evade that conclusion seem even crazier than quantum computing itself: One would have to overturn quantum mechanics, or else find a fast way to simulate quantum mechanics using today’s computers.
Comment #19 December 6th, 2011 at 8:27 am
Aram #11:
What is the classical cryptosystem whose analysis involves quantum computing?
Yeah, as you guessed, I was talking about Oded Regev’s awesome paper On Lattices, Learning with Errors, Random Linear Codes, and Cryptography, which based the hardness of a classical lattice-based public-key cryptosystem on the assumed quantum hardness of the shortest vector problem.
I should mention that subsequent to that, Chris Peikert won a STOC’09 Best Paper Award for “dequantizing” Regev’s reduction, and basing the hardness of some lattice-based public-key schemes purely on the classical worst-case hardness of SVP. However, I understand that there are other lattice-based public-key schemes for which we still only know security under quantum assumptions. In any case, the idea of arguing the security of classical cryptosystems by appealing to quantum hardness assumptions has certainly demonstrated its usefulness.
Comment #20 December 6th, 2011 at 8:37 am
Thore Husfeldt #14:
At which point did you abandon the ambition to challenge ten popular misconceptions about quantum computing for the (equally important) quest saying something snarky about Wolfram?
LOL! Well, my original draft said something like, “the mere possibility of quantum computers has all but overthrown a conception of the universe that several famous scientists have championed, and that appealed to me greatly as a teenager.” But then people who read it told me I needed to be specific about which scientists, so I added Wolfram. And just before it went to press, the copy-editor removed “and that appealed to me greatly as a teenager” to get the piece down to the length limit.
Comment #21 December 6th, 2011 at 9:29 am
A full-text search of the Arxiv server for the strings “quantum mechanics” and “is wrong” finds 5708 articles — too many! Searching for the exact phrase “quantum mechanics is wrong” finds 33 Arxiv articles — still too many!
However, searching the Arxiv for “quantum mechanics is wrong” together with “Scott Aaronson” finds precisely one article, which happens to be a terrific 2010 PhD thesis by Yale’s Lev Samuel Bishop titled “Circuit Quantum Electrodynamics” (arXiv:1007.3520).
Bishop’s thesis qualifies as “terrific” in three concrete respects. First, this thesis is strong in all three areas of math, physics, and engineering. Second, it pursues a clear plan: “investigate the opportunities for using these carefully engineered systems [qubit circuits] for answering questions of fundamental physics” … and yes, these questions explicitly include the second alternative of Shor’s Trilemma: “textbook quantum mechanics is wrong” … a possibility that Bishop quotes directly from a 2004 thesis by some guy named Scott Aaronson. 🙂
Third (and most importantly for me) Bishop’s witty conclusion made me smile:
It was surprising to me that in this concluding passage Bishop conservatively hopes for the first (most boring?) alternative of Shor’s Trilemma: that the Extended Church-Turing thesis is wrong. Arguably more exciting (with respect to immediate practical implications) would be the third Shor alternative: fast algorithms for classical factoring. And of course, for a great many people (well, me for one) the second alternative of the Shor Trilemma is the most exciting and plausibly even the most likely one: quantum dynamics beyond the standard textbooks. Time will tell.
Comment #22 December 6th, 2011 at 9:30 am
Very nice article!
Comment #23 December 6th, 2011 at 10:40 am
I very much enjoyed your essay and interview.
Can you comment further on the part of your essay where you refer to photosynthesis being connected to quantum computing principles? I heard this claim a couple of years ago in a talk and honestly wondered how substantive the connection actually is (as opposed to being a case of using buzz-words from quantum computing to make something seem sexier). Now I wonder if I was overly grouchy in my skepticism.
Comment #24 December 6th, 2011 at 12:06 pm
Alexander #23: To me, the strongest connection has probably come from Alan Aspuru-Guzik’s work — he’s explicitly related the behavior of a photon traveling through a photosynthetic molecule to that of a walker in the conjoined-trees quantum walk algorithm.
What no one seems to dispute is that
(1) understanding the efficiency of photosynthesis (and how we could replicate it in solar cells) is an enormous scientific problem, and
(2) the explanation fundamentally involves a coherent quantum effect.
The debatable point is whether quantum computing and information ideas actually provide any new insight, over and above the techniques that quantum chemists already knew. While I don’t know the details, this debate seems analogous to another debate that I do know more about: namely, the one surrounding the use of quantum computing techniques to prove new classical complexity results.
In any situation where someone uses quantum computing language to understand something that’s not a quantum computer, someone can justifiably say: “eh, we could’ve gotten the same conclusion without using these sexy buzzwords.” But this feels a bit like a master assembly programmer from the 1950s looking askance at these newfangled FORTRAN and LISP programs, saying “eh, I could’ve easily coded that in assembly language!” In both cases, it seems reasonable to predict that the more powerful language will eventually win—the only question is when.
Comment #25 December 6th, 2011 at 12:21 pm
I’m really looking forward to Wolfram replying in a WSJ editorial.
Comment #26 December 6th, 2011 at 2:47 pm
I think you might want to take a look around Dwave’s “deep dive” on their web site… they seem to have managed to build a practical quantum computer, albeit with some limitations as to the parameterization of probabilities.
I believe it’s those limits of resolution and noise that will keep it from being practical for all but the smallest niche of problems.
Comment #27 December 6th, 2011 at 3:18 pm
It was a very good article, and i’m forwarding it to all my family members, but i have two minor issues with it. The first one is that wolfram comment may lead people, who have not seen the header on your blog, to believe that quantum computers can’t be simulated by classical ones, and I think this is a fairly important point.
The second is that “if the universe is a computer then…” is way less cool than my favorite quote of yours, “Of course the universe is a computer! The only question is, what kind of computer?”
Comment #28 December 6th, 2011 at 3:35 pm
Austin #27: Sorry about that! I thought the following sentence made the point reasonably clear:
Quantum computing has challenged that vision by showing that if “the universe is a computer,” then even at a hard-nosed theoretical level, it’s a vastly more powerful kind of computer than any yet constructed by humankind.
But I agree that, even within the 1200-word limit, I should’ve found some way to be clearer about it.
Comment #29 December 6th, 2011 at 4:11 pm
No no, you were perfectly clear in the article, I just think the other way you said it was cooler and more memorable!
Comment #30 December 6th, 2011 at 5:20 pm
Thanks for your answer to my question about photosynthesis. You’ve related the question to other matters where I think the answer is clear. Of course, the results that use QC techniques to prove classical results are very valuable. Without being able to understand the details of the photosynthesis papers, I’m adopting the more positive attitude that you have about them.
Comment #31 December 6th, 2011 at 9:29 pm
Scott, unfortunately you forgot to mention an important quantum computing application: solving Sudoku puzzles.
Comment #32 December 6th, 2011 at 10:28 pm
Erico #31: LOL! I would’ve happily mentioned that one (or equivalently, any other NP-complete problem), had anyone known how to obtain a superpolynomial speedup via QC…
Comment #33 December 6th, 2011 at 10:30 pm
BTW, at the risk of instigating another flamewar: if you only want to read one thing currently in the NYT, I’d probably recommend Paul Krugman’s column “Send In The Clueless” over my essay.
Comment #34 December 6th, 2011 at 11:07 pm
Erico #31: important question indeed :-). For now can suggest a flow-based (non-quantum) solver, though:
Comment #35 December 7th, 2011 at 12:47 am
Nice article. Krugman’s political analysis is much better than his financial analysis!
Comment #36 December 7th, 2011 at 10:06 am
A thought-provoking and complexity-related adjunct to Paul Krugman’s economic analysis is Steve Denning’s economic analysis in his recent Forbes essay titled “Why We Are In Political Gridlock: The Private Sector Is Dying” (key numbers here).
Denning’s analysis is thought-provoking for academics because a world of diminishing returns on investments is a world in which universities cannot prosper, both for the obvious reason that academic endowments yield small returns, and for the more central reason that education is itself an investment by students — often the largest single investment that a person makes in their lifetime. Thus. if investments in higher education are yielding diminishing returns, then perhaps the far-right Republicans are right to apprehend a “higher-education bubble.”
The relation to complexity theory comes when we ask why investments are yielding smaller returns. Hmmm … shouldn’t humanity’s progressively augmented understanding of math, science, engineering, medicine, and culture be yielding the increasing returns?
Perhaps better than a long post arguing a specific answer, will simply a closing reminder that historically, complexity theory has always had much say about returns on investment and how to increase them.
So what does complexity theory have to say, that usefully extends commentaries like Krugman’s and Denning’s, and lays to rest apprehensions of a “higher-education bubble”?
Comment #37 December 7th, 2011 at 11:07 am
I think it’s worth considering why people want to know how long it’ll be until a quantum computer is on their desk. It’s not easy to get excited about what is going on really far away from where you’re used to sitting, I think if people knew more about what the computer on their desk *is* doing, then it’d be easier to talk to them about what it could be doing without getting bogged down in timescales and specific technology.
Comment #38 December 9th, 2011 at 9:08 am
With reference to comments #23, #24, and #30, various quantum conundrums associated to our present understanding of photosynthesis are nicely illustrated in two recent, successive arXiv preprints: Tiersch, Popescu, and Briegel’s earler “A critical view on transport and entanglement in models of photosynthesis” (arXiv:1104.3883) and Mostame, Rebentrost, Tsomokos, and Aspuru-Guzik’s subsequent “Quantum simulator of an open quantum system using superconducting qubits: exciton transport in photosynthetic complexes” (arXiv:1106.1683).
The second preprint (henceforth MRTA-G) can be read as a response to the various criticisms in the first preprint (henceforth TPB). In essence, TPB argue that “Contrary to what is generally stated, [quantum] entanglement … seems to play no role in [photosynthetic] transport efficiency” to which assertion the MRTA-G preprint presents a nuanced counter-argument that includes a concrete proposal for a next-generation DWave-style quantum simulator, based upon eight qubits, that is said to be “within reach of current super-conducting qubit implementations.”
Not to belabor the point, both articles are worth reading, and (it seems to me) both articles make points that are basically right. To reconcile their two points-of-view, it helps to reflect upon the evolutionary biology of photosynthetic mechanisms and upon the general theory of separative transport processes. In this regard two recommended sources are the recent review by Hohmann-Marriott and Blankenship “Evolution of Photosynthesis” (PMID: 21438681) and J. Calvin Giddings’ older-yet-still-good survey “Transport, space, entropy, diffusion and flow” (PMID:3624351) together with Giddings’ influential textbook Unified Separation Science (Wiley, 1991).
Working through these four references in reverse order, beginning with Giddings and finishing with Aspuru-Guzik and his collaborators, leads us to a nicely structured world-view in which (1) the Giddings-style essentials of separative transport (including but not limited to photosynthetic processes) are (1.a) entropy gradients, (1.b) conserved quantities, (1.c) Hamiltonian flow, and (1.d) space-time localization, leading to (1.e) separative co-transport. In consequence (2) the evolutionary biology of photosynthesis is the story of Nature optimizing Gidding’s separative transport elements on (2.a) the smallest feasible spatial scales, (2.b) the shortest feasible time-scales, with (2.c) the greatest feasible thermodynamic efficiency. We thus appreciate that (3) thermal noise acts to (3.a) help separative transport efficiency via improved localization and (3.a) harm separative transport efficiency via decreased entropic gradients. It follows that (4) we have “the potential to achieve a high level of environment engineering, in such a way that external noise is used to benefit the quantum coherent transfer process”(as quoted from MRTA-G).
For me, one nice thing about the study of transport processes is the dual role of classical and quantum noise, which help us by localizing all the things we humans care about (information, energy, and conserved quantities like charge and mass) at the same time that they harm us by diffusing them. The net result is that we humans can evolve separative processes, design separative processes, and efficiently simulate separative processes. Indeed, the visual and cognitive processes by which Shtetl Optimized readers are seeing-and-understanding these words are concretely realized by Nature as separative transport processes on the smallest feasible spatial scales (membranes in retinal cells and neurons) and the fastest feasible time-scales (the femtosecond scales of thermal relaxation) with the greatest feasible entropic efficiency (the membrane co-transport processes that largely govern cell dynamics).
From this separation-centric point of view, what’s wonderful about modern quantum dynamics is not that information is spread-out through many universes, but rather than information is concentrated by quantum processes in just one of them — the universe that we live in and share.
Comment #39 December 9th, 2011 at 12:50 pm
So you weren’t responding to the dreadful Joshua Rothman thingy in the Globe.
Comment #40 December 9th, 2011 at 1:10 pm
Re: #38 and refs. Isn’t the real issue here room-temperature quantum coherence? My personal consciousness was first raised by Seth Lloyd (“Quantum Information Matters”, SCIENCE, Vol. 319, 29 February 2008, p. 1211) where he states “Entanglement underlies the stability of the covalent bond.”
Also, more radically, Vedral of late. And the Zeilinger group’s buckyball interference experiment (which VV mentions) at 1,000 Kelvin. What happened to temperature as the enemy of h-bar?
Comment #41 December 10th, 2011 at 2:39 pm
Austin #27 “Of course the universe is a computer!”
Scott #28 “Quantum computing has challenged that vision by showing that if “the universe is a computer,” then even at a hard-nosed theoretical level, it’s a vastly more powerful kind of computer than any yet constructed by humankind.”
It seems that Austin’s and Scott’s views are that on some hard-nose theoretical level the universe is a quantum computer. Let me mention that it is quite possible that the universe is rather several non-interacting quantum computers. It is a basic teaching of QI that only few states can be realized by QC based on a single tensor product structure. The universe may well be composed of states that represent several non-interacting quantum computers based on different tensor product structures.
Moreover, we know that there are states that cannot be described via QC based on any tensor product structure and perhaps such states are also witnessed in nature. So perhaps the universe is — several non interacting quantum computers plus some extra stuff which is non interacting with any of them –.
Comment #42 December 10th, 2011 at 5:39 pm
>> The universe may well be composed of states that represent several non-interacting quantum computers
Why so complicated?
Keep in mind that the computer does not really have to simulate the universe – it is sufficient to simulate your conscious experience (btw. how many qbits are really needed for that?)
My best guess is that a brain sized computer is enough to do the job…
Comment #43 December 10th, 2011 at 6:37 pm
Wolfgang, your insight was anticipated by 148 years:
Comment #44 December 11th, 2011 at 9:50 am
John Sidles: That’s a beautiful and justly-famous poem! But alas, for me it also brings back unpleasant memories of high-school English class… 🙂
Comment #45 December 11th, 2011 at 2:28 pm
@ Wolfgang#42
Giulio Tononi is certainly the guy to ask.
http://video.google.com/videoplay?docid=-7502852812875314243
His talk is bulshit-free as far as I can tell, and he’s a great great researcher (also studies sleep, the other side of the coin)
Comment #46 December 11th, 2011 at 6:10 pm
57:44+ … “… learning by exposure to a world which is even richer than we are.”
Would Emily Dickinson agree?
Comment #47 December 11th, 2011 at 7:06 pm
Here’s the lecture as a formal paper.
http://ntp.neuroscience.wisc.edu/faculty/fac-art/tononiconsciousness.pdf
Comment #48 December 12th, 2011 at 4:11 pm
Off topic: this hit my feed, and I thought you might want to know about it. He seems to quote you fairly well, though he typos your last name.
http://theastronomist.fieldofscience.com/2011/12/first-quantum-computer.html
Comment #49 December 13th, 2011 at 12:17 pm
Hey, Scott, write something intelligent, witty, and totally revelatory about the the Higgs announcement. Right NOW.
Comment #50 December 13th, 2011 at 1:32 pm
Oh boy, for those still looking to say snarky things about S. Wolfram, he’s now associated with this conference about the brain being more powerful than a Turing machine:
http://www.producao.ufrj.br/hai2012/index.html
I had thought that his cellular automata stuff was classical computation, so I don’t know his angle on this hypercomputer stuff, which is completely bogus as far as I can tell.
Comment #51 December 13th, 2011 at 6:12 pm
In other — very welcome — quantum news, The Quantum Pontiff has sprung to life with Aram Harrow’s live-blogging of QIP 2012. Plenty of outstanding results, admirably summarized. 🙂
Comment #52 December 15th, 2011 at 3:00 am
Masami #49:
Hey, Scott, write something intelligent, witty, and totally revelatory about the the Higgs announcement. Right NOW.
Sorry for the delay! 🙂 See my comments on Lipton and Regan’s blog here.
Comment #53 December 15th, 2011 at 8:47 am
The wittiest thing I’ve heard was said by the Irish Times:
“The God Particle May or May Not Exist”
Comment #54 December 30th, 2011 at 5:21 pm
Wolfram’s view of QM is not simply that it is wrong- but rather that QM is the result of a particular kind of mobile automaton that builds a causal network in which nodes are updated one-at-a-time so time and space are emergent and invariant of the computer’s operations- observers INSIDE this computation can observe ‘spooky action’ parallelism/ superposition/ entanglement/ etc since their universe is essentially frozen while updates are being applied- so QM is what a classical network built from recursion one-node-at-a-time looks like from the INSIDE- at least that is how I interpret Wolfram’s speculation- in this context a quantum computer [or quantum universe] is more powerful because it harnesses more of the bulk operations of large regions within causal network instead of being confined to using only the nodes on the ‘surface’ at the leading edge of the output
Comment #55 July 28th, 2012 at 1:08 pm
[…] than mine have been struggling with this conundrum. For instance, a while back Scott Aaronson described his struggle to write a column for the New York Times that describes Quantum […]