No particular news to report — it’s about the same as it was 400 years ago, I guess. I just wanted to liveblog from the Taj Mahal, is all. (Jonathan Walgate is the one who suggested it.). Now I’ll go back to looking at it.
Two months ago, you might remember, the gods of humor and blogging saw fit to bestow on me an unexpected gift:
Model 1: But if quantum mechanics isn’t physics in the usual sense — if it’s not about matter, or energy, or waves — then what is it about?
Model 2: Well, from my perspective, it’s about information, probabilities, and observables, and how they relate to each other.
Model 1: That’s interesting!
“For almost the first time in my life,” I wrote then, “I’m at a loss for words … Help me, readers. Should I be flattered? Should I be calling a lawyer?”
Almost three hundred comments later, your answer was clear. Half of you thought I’d be a stereotypical American jerk, epitomizing everything wrong with modern society, if I sought any redress for the blatant plagiarism of my quantum mechanics lecture. The other half thought I’d be a naïve moron if I didn’t seek redress. However, there did seem to be a rough consensus on two topics: first, that as part of any settlement I should “date the models” (at least a hundred people made some joke to that effect, each one undoubtedly thinking it highly creative); and second, that it was probably okay to try to get something from either Ricoh (the printer company) or Love Communications (the ad agency), as long as the proceeds went to charity and I didn’t directly benefit. Since, like any public figure, I now make all decisions by polling my base, I finally had a warrant for action.
After talking things over informally with Warren Smith — the guy who discovered the Ricoh ad in the first place, who just happens (in one of the many ironies of this case) to be studying Australian intellectual property law, and to whom I’m deeply indebted — I next contacted a lawyer from a well-known Australian law firm. Talking to her confirmed my suspicion that many of the armchair legal theories offered in my comments section were simply mistaken. In Australian copyright law, as in American law, you can’t just take someone’s words and use them for commercial purposes without permission or attribution, regardless of any subjective judgments about the “uniqueness” or “specialness” of those words. I was on strong legal ground. But there was also a key difference between the Australian and American legal systems: Australian lawyers are prohibited from taking cases on a contingency basis. If I wanted the law firm to pursue the case, then I would have to pay them up-front.
Disregarding the pleas of my relatives — who at this point were begging me to sue — I instead wrote to Love Communications directly, proposing a settlement to be donated (for example) to a mutually-agreed-upon Australian science outreach organization. We eventually agreed to a settlement of AUS$5,000. Considering the value of Love Communications’ Ricoh account — which the Sydney Morning Herald reported as more than AUS$1,000,000 — I thought the ad agency was getting off incredibly easily, but at least I wouldn’t have to write any more letters or deal with lawyers.
The one remaining problem was to find a suitable Australian science outreach organization to which to donate the $5,000, and that would also be amusing to blog about. As I chewed on this problem, my mind wandered back to my visit to Brisbane in December 2005, and to a conversation I’d had there with Jennifer Dodd — then of the University of Queensland and now of the Perimeter Institute in Waterloo. In that conversation, Jen had told me about a popular-science lecture series in Brisbane she’d founded, called BrisScience. I’d immediately asked her to repeat the name.
“BrisScience,” she said.
“Spell it?” I asked.
“B-r-i-s-Science. Why, is there something funny about the name?”
“No, no, it shouldn’t be a big deal in Australia.”
Aha! I now emailed Jen to ask whether BrisScience had continued its “cutting-edge” outreach programs in her absence. Jen replied that yes, it had, and she put me in touch with Joel Gilmore, BrisScience’s current director. Joel told me that not only was BrisScience still going strong (with the next lecture, by Bill Phillips, being about quantum mechanics), but that he (Joel) also directed another science outreach program called the Physics Demo Troupe, which does hands-on science shows for schoolkids in Brisbane and rural areas. Joel proposed that we donate $2,000 of the settlement to BrisScience and $3,000 to the Physics Demo Troupe, the latter supporting a visit to the Torres Strait Islands in North Queensland. I agreed, and Love Communications agreed as well.
I am, of course, gratified that this sordid southern-hemisphere tale of sex, plagiarism, quantum mechanics, and printers could be resolved to everyone’s satisfaction, without the need for a courtroom battle, and that schoolkids in Torres Strait Island might even learn some physics as a result. But is there one sentence with which to conclude this saga, one sublimely fatuous thought that sums up my feelings toward the entire affair? Wait for it… wait for it…
That’s interesting.
Some people think I have a vendetta against D-Wave Systems and its questionable quantum computer claims (see here, here, here, here, here, here, here, here, here for context). But actually, nothing could be further from the truth. I keep trying and trying to change the subject! Wouldn’t you all rather hear about Wolfram, I say? Or unparadoxes? Or my #1 topic du jour, nothing whatsoever?
Apparently you wouldn’t. From my inbox to my comments section to the hallway, the masses have spoken, and what they want to know is: did I attend D-Wave’s presentation at MIT on Monday, and if so what did I think?
Yes, I attended, in body though not in mind. You see, Monday was also the day of the STOC deadline, so if our guests from D-Wave (Mohammad Amin and Andrew Berkley) were expecting a ferocious skeptic, they instead got a bleary-eyed zombie with visions of MAEXP, P/poly, and 7:59PM EST cavorting in his head.
This meant that Ed Farhi, Isaac Chuang, Peter Shor, and Lorenza Viola had to do most of the questioning. As it turned out, they did a vastly better job than I could have.
As others have pointed out in stronger terms, I’m not a physicist. (On the other hand, the gentleman linked to in the previous sentence is not correct about my being paid by the NSA to discredit Canadian quantum computing efforts: it’s actually the GCHQ and the Mossad.) As such, I can’t directly evaluate D-Wave’s central claim to have built an adiabatic quantum computer, nor have I ever tried to do so. All I can do is point out the many things D-Wave has said to the press (about NP-complete problems, for example) that I know are false, its history of making dramatic announcements without evidence, and its contemptuous attitude toward scientists who have asked for such evidence. For me, that’s more than enough to destroy D-Wave’s credibility on the claims I can’t directly evaluate. After all, the burden of proof is not on me; it’s on them.
However, other people have not been satisfied with this line of argument. “We don’t care who the burden the proof is on,” they say. “We just care whether D-Wave built an adiabatic quantum computer.”
But my physicist colleagues don’t suffer from the same argumentative limitations that I do. At the group meeting preceding the talk, Farhi announced that he didn’t care what the press releases said, nor did he want to discuss what problems quantum computers can solve (since we academics can figure that out ourselves). Instead he wanted to focus on a single question: is D-Wave’s device a quantum computer or not?
What followed was probably the most intense grilling of an invited speaker I’ve ever seen.
It quickly emerged that D-Wave wants to run a coherent quantum computation for microseconds, even though each of their superconducting qubits will have completely decohered within nanoseconds. Farhi had to ask Amin to repeat this several times, to make sure he’d gotten it right.
Amin’s claim was that what looks like total decoherence in the computational basis is irrelevant — since for adiabatic quantum computation, all that matters is what happens in the basis of energy eigenstates. In particular, Amin claimed to have numerical simulations showing that, if the temperature is smaller than the spectral gap, then one can do adiabatic quantum computation even if the conventional coherence times (the t1 and t2) would manifestly seem to prohibit it.
The physicists questioned Amin relentlessly on this one claim. I think it’s fair to say that they emerged curious but severely skeptical, not at all convinced by the calculations Amin provided, and determined to study the issue for themselves.
In other words, this was science as it should be. In contrast to their bosses, Amin and Berkley made a genuine effort to answer questions. They basically admitted that D-Wave’s press releases were litanies of hype and exaggeration, but nevertheless thought they had a promising path to a quantum computer. On several occasions, they seemed to be struggling to give an honest answer that would still uphold the company line.
Two other highlights:
For a theorist like me — accustomed to talks ending with “if there are no questions, then let’s thank the speaker again” — this was exciting, heady stuff. And when it was over, I still had almost three hours until the STOC deadline.
For the past few days I’ve been at FOCS’2007 in Providence, Rhode Island, where apparently I’m supposed to have been live-blogging the conference. This came as news to me. (One of the organizers wrote to ask if I’d be posting live updates. I replied that I might post something eventually.)
The trouble is, I still have tons of “backblog” from my previous trip to Latvia and Germany. And so, in the hopes of someday catching up, without further ado I hereby post some photos from Europe.
Sure, I support moderate-to-liberal Democrats … as a temporary measure until zee vorkers take over zee vorl’ [laughs maniacally]
(The above photos were taken in an underground bunker a couple hours from Riga, which the Soviets secretly built in the 70’s, and to which top Communist party officials planned to retreat in case of a nuclear war. Of course, no provisions were made for the rest of the population. Apparently the Soviets built shelters like these all over Latvia. Most of them were converted to bowling alleys or library storage space, but one was preserved for tourists.)
My gracious hosts in Latvia: longtime colleague (and sometime Shtetl-Optimized commenter) Andris Ambainis, Andris’s Ambai-niece Ilze, and Ilze’s husband Girts.
When I think about Munich, Germany, so many mental associations spring immediately into my mind: the fine baroque architecture, the nearby Bavarian alps, the freshly-baked pretzels that are a Munich specialty, the open spaces perfect for rallies and demonstrations of all kinds — but most of all, of course, I think of Oktoberfest! Here you see me drinking genuine bier served by a genuine bier wench (not pictured) with my gracious hosts from the Max-Planck-Institut für Quantenoptik: Norbert Schuch, Ignacio Cirac, and Michael Wolf.
Taking a cue from the Pontiff, I thought I’d provide three quick updates on my personal life (no, not my personal personal life; that’s none of your business).
What better way to procrastinate than to hear an Australian radio show interview me about the quantum query complexity of the collision problem, public-key cryptography, interactive proofs, computational intractability as a law of physics, and my great love for my high school? The first part of the program is about Australia’s population of cane toads (or rather, “tie-oads”). Then at 32:40, they start in with a report on the FQXi conference in Iceland, and interviews with Max Tegmark, Fred Adams, and Simon Saunders. I’m from 39:10 to 46:50.
A few comments/corrections:
Anyway, at least the um’s and uh’s seem to have been under control, compared to my interview with Lance two years ago.
I know I’ve been a derelict blogger since moving to MIT, allowing far, far too many of you to concentrate on work. But today I’m back with some quality procrastination material.
My colleague (and sometime überliberal commenter on this blog) Aram Harrow points me to a safety video for German forklift-truck drivers, which was posted to YouTube with English subtitles. As Aram says, it starts slow but is definitely worth watching to the end.
It’s funny: just this weekend, I was volunteering with the Cornell Alumni Association at the Greater Boston Food Bank. My job was to unload 40-pound boxes of canned goods from a forklift truck and place them on a conveyor belt. (And no, this is not something I’d normally do. Normally I’d offer to write a check to pay for ten people stronger than I am to unload boxes for the needy. Long story short, I was invited to do this by an individual of female persuasion.)
The whole time I was unloading boxes, I too was a bit worried about forklift safety — but, as I now know, not nearly as worried as I should have been.
…but it’s been discovered by empirical observation that the universe is not, as you famously claimed, the “ultimate free lunch.” Rather, the FQxi Conference on Foundational Questions in Physics and Cosmology in Reykjavik, Iceland is the ultimate free lunch.
Speaking of which, above you can see the discoverer of cosmic inflation himself, together with theoretical physicist Lawrence Krauss on his left, chatting on a glacier only minutes after engaging in a snowball fight.
And your humble blogger, who still can’t parallel park, hoping he’ll be able to steer a snowmobile without falling into any 1000-foot crevices.
Here I am with Cosmic Variance‘s Mark Trodden (who blogged earlier about this conference, saving me a good deal of work).
The dirt above is all area where the glacier previously was, but retreated over the last few decades.
To all those who say global warming is a myth: lo, I have watched a glacier melting with mine own eyes.
The geothermally-heated lagoon where part of the conference was held.
And just in case debating unfalsifiable cosmic hypotheses in a lagoon isn’t tacky enough, a PBS crew (from a show called “Closer to Truth”) was there to film it.
This is said to be the official divide between the North American and European tectonic plates.
In North America this would be a major tourist attraction with hotels, casinos, cotton candy shops, etc. Here it’s just another waterfall.
Curse me lucky charms, there’s no pot o’ gold!
I just got back from a conference in Reykjavik, Iceland (!), on “Foundational Questions in Physics and Cosmology.” Photos and trip report coming soon. For now, please content yourself with the following remarks, which I delivered to the assembled pontificators after a day of small-group conversation in a geothermally-heated lagoon.
I’ve been entrusted to speak for our group, consisting of myself, Greg Chaitin, Max Tegmark, Paul Benioff, Caslav Brukner, and Graham Collins.
Our group reached no firm conclusions about anything whatsoever.
Part of the problem was that one of our members — Max Tegmark — was absent most of the time. He was preoccupied with more important matters, like posing for the TV cameras.
So, we tried to do the best we could in Max’s absence. One question we talked about a lot was whether the laws of physics are continuous or discrete at a fundamental level. Or to put it another way: since, as we learned from Max, we’re literally living in a mathematical object, does that object contain a copy of the reals?
One of us — me — argued that this is actually an ill-posed question. For it’s entirely consistent with current knowledge that our universe is discrete at the level of observables — including energy, length, volume, and so on — but continuous at the level of quantum amplitudes. As an analogy, consider a classical coin that’s heads with probability p and tails with probability 1-p. To describe p, you need a continuous parameter — and yet when you observe the coin, you get just a single bit of information. Is this mysterious? I have trouble seeing why it should be.
We also talked a lot about the related question of how much information is “really” in a quantum state. If we consider a single qubit — α|0〉 + β|1〉 — does it contain one bit of classical information, since that’s how many you get from measuring the qubit; two bits, because of the phenomenon of superdense coding; or infinitely many bits, since that’s how many it takes to specify the qubit?
You can probably guess my answer to this question. You may have heard of the “Shut Up and Calculate Interpretation of Quantum Mechanics,” which was popularized by Feynman. I don’t actually adhere to that interpretation: I like to discuss things that neither I nor anyone else has any idea about, which is precisely why I came to this wonderful conference in Iceland. I do, however, adhere to the closely-related “What Kind of Answer Were You Looking For?” Interpretation.
So for example: if you ask me how much information is in a quantum state, I can show you that if you meant A then the answer is B, whereas if you meant C the answer is D, etc. But suppose you then say “yes, but how much information is really there?” Well, imagine a plumber who fixes your toilet, and explains to you that if the toilet gets clogged you do this; if you want to decrease its water usage you do that, etc. And suppose you then ask: “Yes, but what is the true nature of toilet-ness?” Wouldn’t the plumber be justified in responding: “Look, buddy, you’re paying me by the hour. What is it you want me to do?”
A more subtle question is the following: if we consider an entangled quantum state |ψ〉 of n qubits, does the amount of information in |ψ〉 grow exponentially with n, or does it grow linearly or quadratically with n? We know that to specify the state even approximately you need an exponential amount of information — that was the point Paul Davies made earlier, when he argued (fallaciously, in my opinion) that an entangled state of 400 qubits already violates the holographic bound on the maximum number of bits in the observable universe. But what if we only want to predict the outcomes of those measurements that could be performed within the lifetime of the universe? Or what if we only want to predict the outcomes of most measurements drawn from some probability distribution? In these cases, recent results due to myself and others show that the amount of information is much less than one would naïvely expect. In particular, the number of bits grows linearly rather than exponentially with the number of qubits n.
We also talked about hidden-variable theories like Bohmian mechanics. The problem is, given that these theories are specifically constructed to be empirically indistinguishable from standard quantum mechanics, how could we ever tell if they’re true or false? I pointed out that this question is not quite as hopeless as it seems — and in particular, that the issue we discussed earlier of discreteness versus continuity actually has a direct bearing on it.
What is Bohmian mechanics? It’s a theory of the positions of particles in three-dimensional space. Furthermore, the key selling point of the theory is that the positions evolve deterministically: once you’ve fixed the positions at any instant of time, in a way consistent with Born’s probability rule, the particles will then move deterministically in such a way that they continue to obey Born’s rule at all later times. But if — as we’re told by quantum theories of gravity — the right Hilbert space to describe our universe is finite-dimensional, one can prove that no theory of this sort can possibly work. The reason is that, if you have a system in the state |A〉 and it’s mapped to
(where |A〉, |B〉, and |C〉 are all elements of the hidden-variable basis), then the hidden variable (which starts in state |A〉) is forced to make a random jump to either |B〉 or |C〉: you’ve created entropy where there wasn’t any before. The way Bohm gets around this problem is by assuming the wavefunctions are continuous. But in a finite-dimensional Hilbert space, every wavefunction is discontinuous!
We also talked a good deal about the many-worlds interpretation of quantum mechanics — in particular, what exactly it means for the parallel worlds to “exist” — but since there’s some other branch of the wavefunction where I told you all about that, there’s no need to do so in this one.
Oh, yeah: we also talked about eternal inflation, and more specifically the following question: should the “many worlds” of inflationary cosmology be seen as just a special case of the “many worlds” of the Everett interpretation? More concretely, should the quantum state you ascribe to your surroundings be a probabilistic mixture of all the inflationary “bubbles” that you could possibly find yourself in?
Other topics included Bell inequalities, the definition of randomness, and probably others I’ve forgotten about.
Finally, I wanted to take the liberty of mentioning a truly radical idea, which arose in a dinner conversation with Avi Loeb and Fotini Markopoulou. This idea is so far-out and heretical that I hesitate to bring it up even at this conference. Should I go ahead?
Moderator: Sure!
Well, OK then. The idea was that, when we’re theorizing about the nature of the universe, we might hypothetically want some way of, you know, “testing” whether our theories are right or not. Indeed, maybe we could even go so far as to “reject” the theories that don’t succeed in explaining stuff. As I said, though, this is really just a speculative idea; much further work would be needed to flesh it out.
Yesterday I loaded up my Prius with books, computers, bedsheets, a garbage bag full of underwear, and a summer student named Eyal Dechter, and we drove for twelve hours from Waterloo to MIT. This drive, while historic, was largely uneventful; the main obstacle we encountered along the way was the state of New York. Still, it was good to have someone around to share the driving, argue about the survival prospects of the human race, and point out when I left my parking brake on.
In return for helping deliver me to my new job alive, Eyal asked for just one thing: a list of papers in quantum computing and information that make explicit connections to foundational issues in physics, connections that even a physicist could recognize as such. (If we allowed implicit connections, we’d have to include pretty much every quantum computing paper ever written.)
There are many requests I can’t satisfy, but this isn’t one of them.
[AbramsLloyd] [AharonovJonesLandau] [Bacon] [BlumeKohoutHayden] [BriegelRaussendorf] [CavesFuchsSchack] [vanDam] [FarhiEtAl] [FreedmanKitaevWang] [Fuchs] [GottesmanPreskill] [Hardy] [Hardy] [KitaevMayersPreskill] [LiuChristandlVerstraete] [Lloyd] [Nielsen] [Smolin] [Spekkens] [TerhalDiVincenzo] [TonerBacon] [Vidal]
Notes:
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