Thursday, January 29, 2009


The Blanton flaked out on us. Tonight's talk will now be at Welch Hall 2.246 at 8:15pm. We will meet in the courtyard in front of the Blanton at 8pm sharp and walk (approx 5-10 min) together to Welch. If you know where Welch is, feel free to meet us there. Free and open to the public, please invite anyone.

Wednesday, January 28, 2009

First grade science fair

This morning I was recruited (enlisted?) into judging the first-grade entries at the Lee Elementary science fair. It was particularly challenging to calibrate my expectations for what kindergartners and first-graders can reasonably be expected to do/understand and consequently I found it difficult to come up with constructive things to say. A few thoughts.

First, the adults (parents / teachers) are not very clear on the meaning of a hypothesis. Even the form we were to fill out had it wrong, saying something like: "Did they predict the answer?" This understanding of "hypothesis" -- guessing the answer -- is as common as it is unfortunate. Unfortunate because the children (and obviously some adults) interpret this as direction to get the "right" answer. In science (and, I'd argue, life) there are no correct answers, only correctly-executed experiments! A hypothesis isn't a prediction, it is a falsifiable proposal of what result could, in principle, answer a question. For example, the best experiment in my group was about preservatives used on apples. The hypothesis should have been stated as "[Citation] says that lemon juice is useful as a fruit preservative. We wondered if it was better than water? If lemon juice does work well as a preservative we would expect that a water-treated control apple would be browner than a lemon-treated sample." The key aspect of a hypothesis is not that you are predicting the answer but rather that you are stating what result would, in principle, support or refute the theory.

Second, I had a very hard time with the non-experiments. I found myself prejudiced against the "demonstration" and "collection" entries. It isn't that I don't see the value in such real-world work but rather that such entries are poorly defined. What amounts to a good demonstration or collection is very fuzzy -- closer to art than science. There were several presentations that amounted to little more than a cut-and-paste job from Wikipedia (obviously directed and printed by parents.) It took me a few minutes before I got over my negative response to these, independent of the parental contributions; I thought about how often it is that I find myself presenting to peers a summary of existing work as opposed to my own novel experimental findings. Once I thought about it like that I felt better. I came to the conclusion that what's missing from most of the demonstrations is that the children are not asked to look with a skeptical eye on the facts but rather to reguritate authority.

For example, one demonstration was a summary of natural history. It was a nicely drawn time line with pretty illustrations but was filled with exact cut-and-pasted factoids from Wikipedia (at least they cited the source!). I wrote on that one, "Beautiful drawings! A nice overview of natural history. Where does the evidence about these animals come from? For example, fossils. Are some of the fossils more common than others? Where are the biggest gaps in the fossil evidence?"

I wrote similar things on all the other demonstrations. It seems to me that a demonstration should be thought of as a guide that helps others to know where there's research to be done and emphasizes the view that science is not about answers but questions. In effect, a good scientific presentation is more interested in what isn't known than what is. This is obviously hard for a first-grader but I don't think it's impossible.

The demonstrations that regurgitate facts reinforce the false view that science is just another kind of authority figure -- like a teacher or religious book. This view is, again, as common as it is unfortunate. Media, politicians, teachers, and all too often scientists themselves, promote this false perception with statements like "Scientist say that..." with some air of "and therefore shut up". Science is not an authority figure! Indeed it was founded on exactly the opposite principle, that authority is to be *explicitly rejected*. The motto of the first scientific organization, the Royal Society, is "In Nullis Verba" roughly "On the words of no one." A good scientific argument is not "you should believe me because I say so" but rather "look at these interesting findings I have... I draw your attention to the fascinating mysteries revealed by this work." Ideally, science is hospitable -- it offers up the evidence like a well-planned party and invites the guests to join in and enjoy the evidence by thinking for themselves.

That ideal is, of course, not always fulfilled but we might as well try to instill it in first-graders doing demonstrations and collections. Essentially, demos shouldn't cite factoids without being skeptical of them. They should dwell on the methods used to find this evidence at least as much, if not more, than on the facts themselves. For example, that natural history poster mentioned above could have had the exact same time-line, been 1/4 as detailed, and simply showed some pictures of fossils (or ideally, real-life examples) and said: "There's lots of fossils of dinosaurs in this time." and "There's very few fossils before this time. Maybe it's because the animals were too soft to be preserved, but maybe they have just been over-looked for some reason." Just a few sentences like that would have been much more scientific than the pages of copied Wikipedia factoids.

Tuesday, January 27, 2009

Protocells Book

The book "Protocells" came out recently in which my friends Jeff Tabor, Matt Levy, Andy Ellington and myself have an paper entitled "Tragedy of the Molecular Commons". Check out the high-quality binding from MIT press. Angel pointed out that it's a convertible book: either hardback or paperback! There's many interesting articles in the book and therefore provides further evidence that you shouldn't judge a book by its (unglued) cover.

Monday, January 26, 2009


Today was the kind of day where it occurred to me that Sisyphus had it easy. First, he had only one rock to push up the hill and second, the gods made him do it so he had someone to blame other than himself.

Sunday, January 25, 2009

Usual weekend masonry

Progress on the back wall. I've finished the back wall minus the end cap. In these pictures you can see the "sketch" of the end cap where a planter will go and filling-in of the CMU block foundation that will be the back of the BBQ / fire pit. That's ~400 lbs of concrete I moved around this weekend and it barely looks different!

Monday, January 19, 2009

Lecture at the Blanton Thus 29 January, 8pm

I'm going to be giving a talk at the Blanton Museum Thus 29 January, 8pm. The title of the talk is "The evolution of evolutionary design". I promise to touch upon every one of the following in less than an hour:

Ornamentation, history of
Algorithms, genetic
Craftsmanship, death and rebirth of
Art, definition of
Culture, development of
DNA nano-technology
Robots, self-replicating
Affine programs
Whale sperm
Suburban architecture
Cell phone towers
Life, meaning of

As you can see, it's going to be your basic run-of-the-mill art talk. ;-)

I will also be demoing for the first time in public progress on a new art project from my new company "Genetic Art Design, Inc". If you haven't been to the Blanton before, you should come just to look around, it's a nice place. Hope to see you there!

Interactive Ruben's tube prototype Mark II & III

Aaron and I worked on the 2nd and 3rd prototypes of our interactive Rubens Tube idea for next years First Night. Today we used a more practical solution with metal dryer conduit and a rubber glove as a membrane with the speaker disconnected from the tube. It's fascinating how responsive these are the volume of the music. It burns consistently brighter when the volume is higher which makes little sense to me -- spatial standing waves make intuitive sense but I don't understand why it generates a such a dramatic spatial DC response. One theory we had is that somehow vibration is changing the mixture ratio but it's not clear why. Our plan is to have about 100 of these floating on the lake so we started discussing the practicalities of floating them and addressing them each uniquely over various possible data lines. Our next experiment is going to use small campsite propane bottles to test duration and what happens if you don't have a pressure regulator.

Sunday, January 18, 2009

Mathematical pedagogy II

One time I overheard a mother say about her daughter, "My girl is great at math except she has a hard time with word problems." I thought to myself was: "Then your girl isn't good at math!" Only in school is "math" a game of manipulating disconnected numbers. Math is word problems (although they become increasingly abstract). As many people do, this mother was confusing arithmetic for math.

Arithmetic is not the same things as math; the distinction is very important. Mathematics -- the exploration of pattern by means of proof -- has not substantially changed in the last 2500 years. But arithmetic -- the computing of numerical values -- has changed beyond all recognition in the last 50. The fastest human arithmetical savant might be capable of adding a few numbers per second. To say computers eclipse that isn't even close. Even a cheap cell phone can do 100 million arithmetical operations per second; an inexpensive computer can do 3 billion per second. Going from 10 to 10 billion in 50 years isn't "change", it's "conquest". It is absolutely absurd to ask a human being to do an arithmetical task. When your free cell phone, cheap watch, or low-end TV can out-perform you by a factor of a billion, it's time to stop competing.

An analogy. For thousands of years people have fetched well water by gracefully carrying large jugs on their heads. One day a pipeline is built and water can be delivered directly into everyone's house. The pipelines didn't improve the porting of water, they eliminated it. Imagine a teacher saying to a class: "We must learn the art of porting water on our heads! Carrying water on your head is good for your balance, strength, and poise!" When inevitably the children don't want to practice because they can just get water out of a tap, the teacher says: "The children of today are all loafers! Pipes are making everyone stupid and lazy."

Teaching arithmetic in 2009 is like making pupils port water on theirs heads. Arithmetic is a conquered technology. But for one exception -- estimation, to which I will return -- arithmetic simply isn't done by hand anymore. Game over.

Yet "math" in grades 2-6 is still dedicated to arithmetic. (We'd be better off teaching them porting water on their heads, at least that would promote exercise!) As I suggested in an earlier blog, I'm afraid that the principal accomplishment of existing numerical pedagogy is to make a significant portion of the population hate numbers. To illustrate: despite the years dedicated to the subject in school, you can't find any cashier nor any restaurant waitstaff who can sum a bill sans computer, much less compute tax, despite the obvious service advantages. Nobody can or wants to do arithmetic anymore; it's time we admit this and move on. Yet there seems to be a strong reluctance to change the curriculum because of some society-wide nostalgia for arithmetic.

In my opinion, eliminating arithmetic from grade school curriculum is a fantastic opportunity -- now we can dedicate those precious grade school years not to boring arithmetic but to fun and useful math!

In an age of ubiquitous computers lack of even rudimentary computer skills abound. The required skills are more than functional knowledge of email and web-browser -- what's missing is the knowledge of how to frame questions so that they can answered by a computer. The first tool that should be learned is the spreadsheet. If 50 years ago it was necessary that all people should be able to add and subtract, today it is necessary that all people should be able to use a spreadsheet.

Here's what I would do if it were my own children I was teaching. As would anyone, I would start with concepts of magnitude. How big is 7? Make a pile of 7 blocks. Is 9 a bigger than 3? A lot bigger or a little? Next, in continuity with existing curriculum, I'd introduce the concepts of addition and subtraction by adding or removing to a pile. But after that I'd break with tradition. From here forward I'd have my kid sitting in front of a computer spreadsheet program like Excel. We would explore questions learning how to program the spreadsheet to get an answer. We start with questions like "If I had had 3 blocks and then I was then given 6 by Ann and 4 from Bob, how many total would I have?" For this problem, we'd put "Mine" in a column and 3 next to it, then we'd put Anne and Bob's contributions in the next rows and finally type in the excitingly magical phrase "=sum(B1:B3)" and, presto, there's the answer. I'd advance through problems like this always with the of practice solving word problems by converting them into spreadsheets programs. There would never be a big sheet of arithmetic that the pupils was supposed to mechanically work though as is currently the case in grades 1-4. All problems would be word problems. All answers would be spreadsheets.

As we advanced from calculation with spreadsheets into algebra, we'd return to a somewhat traditional curriculum of symbol manipulation but using the computer to sanity check our conclusions and to solve associated word problems. But there would be a few changes I'd make.

First, as before, I'd never present a page full of meaningless algebraic equations to "solve for x". That kind of practice is too mechanical for my tastes. That said, I do think that algebraic manipulation is useful and has to be practiced, but I'd keep it grounded with word problems in every exercise. Second, I'd work to make sure the students can use algebra as a language -- that they can translate questions to and from that language. A game I've played with students before is what I call "reverse word problems". Given an equation like: "5 = x + 3" I'd say: "I have 5 oranges now. I had 3 and my friend gave me some number I can't remember, we'll call it x. How many did he give me?". Once students get the hang of this game, I have been amazed how quickly they can connect these meaningless abstract symbols to their lives. Once when playing this game a girl told me a used-car-lot-based story that involved a sale price on a used car. I loved it and asked her how she came up with it and she told me that her father sells used cars; this was a girl that just 30 minutes earlier had told me that she hated math because she didn't see the point of it!

A common response to proposals for introducing calculators into math curriculum is that the students who rely on calculators don't have any intuition for numbers and are prone to draw ridiculous conclusions when they mistype something on the calculator. For example they are capable of writing "10+5 = 50" because they pressed multiply instead of add and have no intuition for that being absurd. This is a very valid concern. I would address this in two ways. First, I would never use a calculator in a classroom, only spreadsheets. Calculators show only the current operand and never show the operation so the user can not go back and check that things were entered correctly. Calculators are therefore so error-prone that I never use them except for extraordinary circumstances. Second, and more importantly, I'd teach number estimation as completely separate exercise from computation. Estimation is wildly undervalued and should be taught regardless of whether or not you believe in eliminating the arithmetical curriculum. (As an interesting aside, I've noted that all my nerd friends over 60 can estimate extremely well because they were all slide rule masters which required them to keep track of magnitude in their heads while using the slide rule for the mantissa.)

I would teach number estimation with just two key ideas. First is the idea of an order-of-magnitude. Strip off all the significant digits and just deal with the magnitude. Multiply and divide are then just slapping on and off zeros. I'd do all this exercise with classic Fermi problems such as estimating the volume of the earth and so forth. All of these exercises would be played (with supervision) with Google. Google the diameter of the earth. Simplify this to an order of magnitude, cube it, etc. Then write down your order-of-magnitude estimate and then look up the real answer with Google. The second tool I teach is doubling and halving. Want 8 times of something? Double it three times. Want 9 times? Double it three times and add some more. Want to divide by 5? Half it twice and take some off.

In summary, if teaching my own children math, I'd abandon arithmetic, emphasize spreadsheets, avoid calculators, always use word problems, ground algebra with reverse word problems, and teach estimation as it's own computer-less skill with Fermi problems and Google.

Saturday, January 17, 2009

Interactive Ruben's tube prototype Mark I.

Aaron and I started work on a prototype of an interactive Ruben's tube that we're thinking of proposing en masse for next year's Austin First Night. The The lessons for tonight were: 1) Yes, PVC is quite flammable at propane temperatures. 2) The speaker needs a tight seal or it catches on fire 3) It needs a diffuser because the pressure ends up too high on one end. 4) Metal tape doesn't work because the glue melt and ignites 5) Need a longer tube 6) MSVC 9.0 infuriatingly has an issue with DirectX 8.0 SDK headers.

Monday, January 12, 2009

How tools become abstractions, The Value of tinkering, and Mathematical pedagogy

I started programming computers when I was about 10; I had no idea what I was doing of course, I just followed the examples in the Apple and TRS-80 books. Meanwhile, part of tinkering with a computer also meant using the stock tools such as the commands to copy files, list directories, or fetch the time. I don't remember the exact day it happened, but there was some point that I realized that the commands like "copy" and "dir" were just programs like the ones I was writing -- that I was capable of making, in principal if not yet in practice, the tools I was using. That realization is a kind of magic moment in mastering a medium -- the moment when you see a tool beyond its immediate utility into the deeper concept that it embodies. You go from a tool-user (imitating the tool's use with variation) to a tool-maker (exploiting the under laying principal).

Tinkering begets insight. For example, when you tinker with woodworking tools you use the tools, hammers, drills, nails, etc. for their intended purpose without considering how they work. A nail is a device which accomplishes the task of attaching two boards, and a first you don't see past that utility. But as you become more intimate with the process at some point it may occur to you that a nail is just a kind of friction joint or that a screw is just a wedge wrapped around in a circle or that a drill is a kind of special scraper. When you see these kinds of things your mind opens up. If a nail is a friction joint then what other kinds of friction joints are possible? You might invent a dowel joint having never seen one before. If a screw is a curved wedge that buries itself into the material, what other ways can a wedge be integrated into a structure?

There are many people who never pass the tool-using stage of their craft. They stay within the existing rules of their medium and are perfectly comfortable there. I don't mean to be critical of that approach. That said, I can't help but think that the reason that some craftsman don't go past the tool-using stage is that for whatever reason they simply haven't had enough "a-ha" moments to internalize the drive to abstraction. One reason for this, I believe, is that most formal pedagogical practices try to shortcut the process of tinkering. There's a strong temptation when teaching something to cut to the chase; many teachers end up acting as if teaching someone something is about giving them answers instead of guiding them to the answer.

While I'm advocating the advantages of coming to understand tools as abstractions, I don't think that this learning process can be far removed from tinkering. As proof, I submit the typical pedagogy of mathematics as an extreme demonstration of how abstraction without tinkering goes horribly awry. To illustrate, imagine that you took a shop class but had never before seen any woodworking -- nails, screws, drills, all of it was totally new to you. Imagine if the teacher began the first day of class by saying: "OK class, this is a hammer. A hammer is characterized by a relatively large hard mass attached to short lever usually, but not always, made of wood. Note the counter-balanced curved metal head called a claw. Everyone pick up your hammer now and follow along with me banging the hammer on the table. One (BANG), Two (BANG), Three (BANG). OK class, now this is a drill. A drill is a helical scraper whereby a pitched screw... blah, blah, blah." Imagine this kind of boring technical analysis of woodworking tools day after day. On the last day of class a pupil raises her hand and asks: "Teacher, I have paid close attention and have learned about all of these tools, but I'm not clear on what it is you DO with these tools." and the teacher responds: "I'm not really either sure as I've never done it myself, but I think people make cabinets and chairs and stuff like that, more importantly all of this *is* on the college entrance exams." The kids think: "What?! You mean this class was about making chairs?!"

While this parable is exaggerated, I think that mathematical pedagogy (and other subjects) is not far from this. Most teachers and students intuit addition and subtraction and after that it's a free-fall into meaningless technical abstraction. By third grade, multiplication and long division become so bogged down in symbol manipulation that almost no child leaves understanding what multiplication and division *are*. Later they'll use them as a tool to perform yet even more technical abstractions but all too often 12 years can go by and the pupil still has no idea what you *do* with these tools other than make more abstract tools. I am convinced that the primary societal accomplishment of current mathematical teaching is to make people hate math. Those few nerds who make it past the abstractions were going to do so even if they hadn't been for the classwork, those who were going to hate it just hate it more, but the majority who might have liked it / used it / appreciated it instead come to despise it after being bludgeoned by it for 12 years. So the net result is that we may be worse off teaching math classes than had we simply done nothing. (My opinions on how to reform this are best left for another day.)

Even in the best case where an excellent and enthusiastic teacher is well practiced and accomplished in the use of the relevant tools of their art, the teaching techniques tend to lack tinkering because of its "out of control" sense. But, without discovering for yourself that a hammer is a solution to a problem, you can't easily appreciate the tool's function and you finally can't abstract the principal of the tool to other problems. If you tinker enough, and if you are lucky enough to have access to someone who has crossed the abstraction bridge, then you can grow from tool-user to tool-maker and, to me, that's the difference between ordinary works and extraordinary works.

Sunday, January 11, 2009

Mythbusters accidentally create a reaction-diffusion-like system

This short video clip shows that the Mythbusters appear to have accidentally and unknowingly created a kind of reaction diffusion system in their "Trailblazers" episode when they ignited a trail of gasoline. If you look closely behind Adam you'll see waves propagating in a manner reminiscent of various reaction diffusion and cellular automata systems. I think what's going on here is that the gasoline vapor and the moving ignition creates a two dimensional amorphous relaxation oscillator. Remember that it is the vapor of gasoline that is flammable, not the liquid. As the fuel evaporates into vapor it takes a few moments before it reaches an ignitable fuel to air mixture. When it does, a wave of flame propagates over the area thus eliminating the vapor which then slowly re-accumulates until it ignites again when it encounters an ignition wave from some other region. The exact position of the flame is highly sensitive to the environment and initial conditions thus the system turns into a set of chaotic cyclically flammable domains that move around in a fascinating manner. Apparently without knowing it, Jamie and Adam have stumbled upon a quite lovely piece of science. I've got to try to reproduce this!

Thursday, January 8, 2009

Keyless Entry

I hate keys. I'm striving for a zero-key life. To that end, I've started on this little electronics project to automate the lock of my front door. There will be a discrete set of switches that look for a magical unlock sequence. I have an odd relationship with electronics. On the one hand I feel like I know the theory fairly well and I'm at home once the circuit is digital and connects to the computer. But in between those two is reality. The circuit seemed simple enough to just solder straight to the board. Bad idea. Meanwhile, I made totally rookie mistakes with the ground and managed to literally cross some wires. Also, I purchased a touch sensor IC (QT1103) because the data sheet said that it had an RS-232 out which is a protocol I know well from BBS modem dayz. Turns out there's a newer protcols (Dallas semiconductor's 1W) which is 100% incompatible with RS 232 yet mysteriously still uses the RS 232 moniker. So that caused me no end of confusion until I finally worked it out with the always helpful Wikipedia. Thanks to John sorting out my stupid mistakes and lending me a scope and protoboard, I've since started to make progress.

Saturday, January 3, 2009

Back wall

Masonry is slow, tedious, heavy, dirty, at times back-breaking. All the pleasure is delayed -- a sense of accomplishment, an "I built that" satisfaction when you're done. I don't think I could have done such a slow and delayed-gratification task when I was young; what changes as we age that permits the patentice for such projects?

Some of the appeal of brickwork is the giant lego-ness of it. Or more to the point, old-school legos when there were only a few generic bricks -- before the marketing department at lego corrupted them into themed monstrosities with an over-reliance on custom single-use pieces. Brickwork tickles a nerdy engineering need for an elegant basis set from which solutions are cleanly constructed. But it lacks the playful impermanence of legos -- while I'm laying them I often think about the fact that these bricks will likely be the most long-lived thing I will make in my life. I wouldn't be surprised if 300 years from now my house has been torn down but the brickwork remains. Building things which are unobtrusive, durable, beautiful, and utilitarian is an almost guaranteed way to make sure they are maintained into the future.

Thursday, January 1, 2009


Been working all week with Andy, Xi Chen, and Nam on a paper. Using the kinetics from Jongmin Kim's bi-stable switch paper, Nam produced a nice simulation of the amorphous ring oscillator. Happily, these images look much like my earlier, cruder, simulation but now have dimensions. Features are measured in mm and time in hours. I think that's pretty cool -- a molecular scale device producing features at the mm scale. Would be great if it actually works when we try it someday!

Also from this this paper, Andy, Xi Chen, and I came up with a hopefully plausible complementary transcriptional NAND gate. The idea is that all signals are encoded by the sense and anti-sense complements of an RNA sequence. For example, signal "A" is high when some specific RNA sequence is high and it is low when the anti-sense of that sequence is high. The hypothetical gate is made from two complementary promoters on opposite sides of an double stranded DNA. On the left side, two molecular-beacon-like devices sequester half of a promoter that activates only when both inputs are high. On the right side, a single hairpin is folded such that a promoter is normally active but is deactivated when A and B invade (thanks Xi Chen). To work, the kinetics will have to be very delicately balanced so maybe it won't work well but at least it's a conceptual step in the right direction; we've been talking about a CMOS analog for years now and this is the first time we've made any conceptual progress.