Month: April 2004

Lance Fortnow undercuts John Quiggin, who in turn undercut William Tozier.

See Ebay. Concept due to William Tozier.

Update: I just (re-)computed my Erdos number. Turns out its 3 (via Erdos, Fan Chung, and Richard Cleve). Maybe I ought to get into this auction action? Lance Fortnow (Erdos number 2) ought to be able to do even better.

Dave Bacon asks why his field doesn’t get enough lovin’ among other scientists:

The number one most irritating question I was asked during my faculty interviews was “what will you do if quantum computation doesn’t pan out?” […] And this is what makes the question so irritating: it implies that quantum information science is a fad with no intrinsic intellectual value. Do you ask string theorists whether what they do will be experimentally testable and if not what will they do? Do you ask astrophysicists whether studying cosmology will have any significant impact on society? No. But because these are part of a long tradition of theoretical physics they are acceptable intellectual persuits, whereas quantum information science, being new and getting too much press is most definitely suspect.

I suspect that in the last sentence Dave has put his finger on part, but only a small part, of the problem. I think there’s an another consideration that plays a much bigger role.

String theory, astrophysics, and (to a lesser extent) condensed matter and AMO physics have all done a terrific job of articulating why they matter. They’ve identified deep central questions that are relatively timeless and unarguably important. Furthermore, they’ve communicated those questions clearly and repeatedly, not just within physics, but to other scientists, and, in some instances, to the public at large. Even if the specific approaches they are taking to those questions fail to work – maybe string theory won’t pan out, or gravitational waves won’t be detected, or whatever – the questions will remain important.

Contrast this with quantum information science. Most presentations on quantum information science I’ve seen motivates the field either by saying (a) quantum computing has important practical applications, and so should be pursured, or (b) by making vague allusions to the importance of better understanding quantum mechanics.

In short, the quantum information science community hasn’t fully articulated a sensible narrative containing questions that are big, timeless, and important. And until such a narrative has been articulated, and communicated to the world at large through review articles, overviews, technical and popular books, other scientists will wonder legitimately about the value of the field.

This problem isn’t unique to quantum information science, of course. I’m just using it as an example because Dave used it, and I happen to feel strongly about it. The problem affects many other fields; a good example is complex systems research, which I’m pretty sure has suffered some of the same problems, though in somewhat different ways.

I’m personally convinced that there are big and timeless questions that can be addressed by the techniques of quantum information science. I’ve tried to describe some of these questions here and here and here. (The first article is in Scientific American, and I’m not sure it’s accessible without an institutional subscription.)

This really needs a lengthy post, but in brief I think a big and important problem that can be addressed by quantum information science is to understand the behaviour of complex quantum systems. That is, we want to find general principles governing complex quantum systems, and determine what makes them different from complex classical systems.

This problem is not unrelated to some of the central problems of condensed matter physics, but I think there’s a key difference in approach. Quantum information science starts by taking quantum mechanics very seriously – some would say too seriously – and asking what is possible within the confines of that theory. Condensed matter physics has been much more motivated by experiment, and by the pursuit of some key theoretical models. I think that’s a great thing – condensed matter physics has had fabulous successes beyond number – but I do think the different perspective of quantum information science has something important to contribute.

I’ve said before that I think the so-called “cluster states” are one of the most remarkable recent breakthroughs in quantum computing. One entangled state plus localized measurements is enough to simulate any quantum system! Here’s a link to my journal club notes on the subject. They require a background in quantum mechanics, but should be very easy to read if you’re part of the quantum computing community.

Thanks to Debbie Leung for providing the small pdf file (it was originally 16 meg). I’m posting this in part because Debbie and Panos Aliferis posted a paper yesterday that references these notes.

Our field is still in its embryonic stage. It’s great that we haven’t been around for 2000 years. We are still at a stage where very, very important results occur in front of our eyes.

– Michael Rabin, on the field of computer science

In natural science, Nature has given us a world and we’re just to discover its laws. In computers, we can stuff laws into it and create a world.

– Alan Kay

I am large, I contain multitudes.

– Walt Whitman (“Song of Myself”)

Note: This is the first part of a rather lengthy two-part post. It’s written in a style that is, I hope, accessible to an informed lay audience until near the end, when some undergraduate physics would help. The piece describes in a fair amount of detail a scientific problem that I think is important, and why I think it’s important. It’s very much an early draft, and feedback is welcome.

Chad Orzel posts a credo. It’s a humbling and thought-provoking experience to read something like this; I’m not at all sure what my credo would say. I especially liked this part of Chad’s credo:

I believe Terry Pratchett when he writes that treating people as things is the origin of the only true sins.

Striking paragraph on the connection between learning, stories and emotion, via Seb’s Open Research. (you can see the chain of links there).

The key quote is from John Seely Brown.

Why storytelling? Well, the simplest answer to your question is that stories talk to the gut, while information talks to the mind. You can’t talk a person through a change in religion or a change in a basic mental model. There has to be an emotional component in what you are doing. That is to say, you use a connotative component (what the thing means) rather than a denotative component (what it represents). First, you grab them in the gut and then you start to construct (or re-construct) a mental model. If you try to do this in an intellectual or abstract way, you find that it’s very hard, if not impossible, to talk somebody into changing their mental models. But if you can get to them emotionally, either through rhetoric or dramatic means (not overly dramatic!), then you can create some scaffolding that effectively allows them to construct a new model for themselves. You provide the scaffolding and they construct something new. It doesn’t seem to work if you just try to tell them what to think. They have to internalize it. They have to own it. So the question is: what are the techniques for creating scaffolding that facilitate the rich internalization and re-conceptualization and re-contextualization of their own thinking relative to the experience that you’re providing them? Put more simply: how do you get them to live the idea?

A while back I wrote an extended post about the culture of academia, and how success and failure are defined within that culture.

In the comments to that post, Seb Paquet just posted a link to an interesting related article by Alex Pang about his experience in leaving academia.