16 April 2013, 9:55 UTCAcetone vapour [detonation] chamber for ABS plastic smoothing
There's been some recent discussion of smoothing 3D printed ABS plastic objects using acetone vapour, eg on the RepRap blog. The general approach seems to be to heat the acetone gently. I think this is a mistake, acetone already readily evaporates at room temperature. The real problem is to apply the acetone uniformly to the model.
To this end, I've constructed a simple enclosure containing a fan mounted on the side wall to circulate vapour within the chamber. The lid has a tiny hole in it to release pressure (otherwise the lid pops off). The printed pieces sit on a small metal stand so as not to be bathed in the liquid acetone at the bottom of the chamber.
The alert amongst you will note this is a great way to create an explosive fuel-air mixture. It hasn't exploded on me... yet. Hopefully, if it does explode, the lid will pop off and direct most of the blast upwards.
The recorder on the left is untreated, while the recorder on the right has had half an hour in the chamber. Shiny!
10 April 2013, 8:06 UTCDigital devices for the punk
Analogue glitches well. There's a great deal of nostalgia for it. Steampunk. Our digital devices do not glitch nearly so well. Usually, they either work or don't. The noise level on a channel determines how much data can be pushed through it, the Shannon limit. If that is exceeded, the channel fails entirely. Basic information theory. Except, it doesn't need to be this way. We can imagine digital devices of the same complexity to the ones we have today that don't behave like this. Take digital TV. If the signal is good enough it's perfect, otherwise it's unwatchable. Clearly in reality different receivers have different noise levels. The current design ignores this. It is therefore a poor design. There's nothing stopping us boosting the redundancy of some part of the signal, and reducing the redundancy of another part, so every receiver can at least get part of the signal.
Lossy coding is easy, and receivers can continue to improve after the protocol is specified. A smart receiver could take a degraded signal and make a best guess, degrade toward a cartoon, hallucinate to an acceptable degree. In other words, glitch. Like analogue, only far more wonderfully.
5 March 2013, 1:39 UTCAlternative architecture: Giant roundhouse
Modern architecture is built on squares and rectangles. Variations on the courtyard. Spaces in which people face each other full on.
Can we imagine an alternative line of architectural development from the roundhouse? What would such a building look like once it got large. Low, cosy, like a bowl haircut of a building, a central fire, but vast. Elements of a stadium or a theater or parliament but I'm also imagining something sunk into the earth, bound to the earth and anchored to it with solid pillars. The entrance low and wide, one proceeds slightly downwards to the building's core chamber. Acoustics of thatch, not echoing, defined spaces but less need for walls if the surfaces are acoustically absorbing (but a larger meeting space might need more reflective surfaces). Permeable, a breathing building, adaptive to seasons.
15 February 2013, 13:15 UTCRockstar job market
In the future, the job market is going to look a lot like Valve Software. A company of rock stars, no defined roles, you are either adding value or not. It's not for everyone. It's not for most people. Valve isn't a charity, it doesn't owe people a job.
We've come a long way on the idea that everyone is owed a job, that if they're good enough you deserve a life-long career. We've rigged and rigged the system to keep it going, but it's still falling apart. Capitalism outgrew and swatted aside the invisible hand of nationalism.
So, take that seriously. Let capitalism do the thing that it does well, and let government and volunteer organizations do the other things that need doing. Your employer doesn't owe you a job, a retirement plan, healthcare, a fullfilling experience, a place to get away from the kids, people to boss around. Your academic study does not entitle you to job fullfillment or an academic position. Society perhaps should give you a universal wage, and encourage you to get a hobby. By all means pursue your interests. Publish in a journal! Well, blog. Maybe one day, for a while, you'll have that particular mix of skills that is actually useful, and you'll get a job for a while. Chances are heavily against it. Or maybe you'll help get someone started who is actually useful, teach them the rudiments of a skill they'll soon excel you in. In the meantime, be happy, make a few other people happy, and try not to get in the way of people with real jobs.
This is the good outcome, the one in which most people don't die.
13 February 2013, 8:04 UTCClostridium perfringens story
Suddenly we few are in a turgid broth of plenty. Will our daughters remember when this broth was vast, empty, delicious, free of the bodies of their dead sisters and cousins? Will their daughters remember the time before, the cold times, the sudden shocking heat, the lonely times, the crowded times? Will their daughters remember the harshest of times, when we became endospores, and be ready should those times come again? Those that remember are cautious and dwindle, those that forget are carefree and increase. Will their daughters' daughters' daughters remember the harsh wonderful environment of flesh that is our true home, written in the bones of our chromosome and our plasmid weapons, the place of our true expression? Will our descendants remember anything but an endless zero-sum game?
No. We lyse. We will not be daughters. RNA obscenely becomes DNA. Hamfisted aliens will pick through the dead soup of our mingled memories.
12 February 2013, 0:23 UTCThings that Professor Richard Dawkins will never say
- Atheism lets me care for the people I love. It's all about being there for them, y'know, being totally in the moment, just me and them.
- I have an idea or two, I want to know, I think it maybe is knowable, but I don't know, nobody does. "We don't know" is the position I'm going to be advocating here.
23 November 2012, 3:20 UTCMixture-model of politics, with application to climate change
The left-right model of politics is inedequate. People's views on various issues can't be compressed to a single parameter.
Left - Right
Authoritarian Left + Right Libertarian
This seems nicer, but I suspect creates a false distinction. There's not much practical difference between an authoritarian left and an authoritarian right, it's still just a few people in charge. I instead propose a triangular model:
Hierarchy Individualism Communism
A society is composed of a mixture of these three forms of decision making. WWII saw a fight between pure-hierarchy and everyone else, which was followed by an extended argument over the merits of a highly individualist society versus a mixture of hierarchy and communism (heavy on the hierarchy).
It should be noted that although a communist society has been a goal of a lot of a people for at least several thousand years, no one knows how to do it in practice. There is universal lip-service paid to its desirability. It may require a change in human nature, on which point there has been slow but real progress over the past few millennia. Maybe computer networks will help.
Why this matters: We're looking to shoot straight on past the 4-degrees warming scenario. This is very, very bad. In highly hierarchical societies (China), the rulers are unwilling to act to stop this -- better to maintain a hierarchy in hell, genuinely better for everyone is the belief -- whereas in highly individualist societies externalities tend to be under-valued. Our oligarchical west gets a double dose of suicidal tendency here.
There is an argument in the green faction to say "never mind all this social justice stuff, we need to concentrate on global warming.". It's worth meditating for a moment on the scale of horror of this strategic idea (if it helps, imagine it somewhere else on a smaller scale). However, even if we accept that the misery that will be caused by climate change outweighs the misery caused by endless social injustice, which I tentatively accept, I think this is a mistake. While we still live in a world of sexism and class divides, progress will be nearly impossible. Enough!
4 November 2012, 22:56 UTCPeer learning and gender discrimination
I studied computer science, but I learnt Unix from my peers. Unix is ugly and complex, it isn't good material for university learning, it's more like an abstract trade skill. We messed around with various projects, used a student run server called "yoyo", set up websites, etc.
Teachers are well aware of the need to not discriminate by gender, but an undergraduate student? I was not the social butterfly I am now. I lacked the skills to untangle my own motivations. I don't recall collaborating with any female peers on anything technical until I started postgraduate study.
I don't have a solution. Just highlighting this as a problem.
See also: http://adainitiative.org/
28 October 2012, 20:30 UTCDemakein 0.2 release: shawms
I've just released version 0.2 of my woodwind instrument maker. This version adds a shawm designer/maker. The bore shape optimization for the shawms was rather tricky, so the numerical optimzer has also undergone a complete overhaul.
Having printed a shawm, you can use my drinking-straw reed making method to make a reed for it:
24 October 2012, 6:36 UTCGains and trade-ups
Consider two broad classes of favourable life events:
- Gains: A skill or possession is obtained without any loss, except perhaps time and effort. A life of gains is one of gradually increasing skill, wealth, and status.
- Trade-ups: Something is given up in order to obtain something better. A transformation takes place. A life of trade-ups has very distinct stages.
The difference is that a gain can be given up, but a trade-up might not allow a trade-down. A forced gain is only somewhat creepy but a forced trade-up is very creepy. Even a voluntary trade-up is borderline creepy, it's non-reversible and the choice might not be fully informed. The social norm we are heading toward is that consent can be withdrawn at any time, and any trade-up violates that.
- In the stories we tell, the class of life events characters experience is extraordinarily heavily stereotyped by gender.
- This explains the creepiness of certain authors: Walt Disney, Steven Moffat, Anne McCaffrey, Iain Banks. A form of pornography in which the imagined universe satisfies the desires of the author, in which violence becomes inescapable physics.
- Even feminist authors can miss this gender bias: Joss Whedon, Charles Stross (?).
- It explains the odd quality of certain other authors: Cory Doctorow, Peter Watts, William Gibson, Kurt Vonnegut, Greg Egan. The physics of the imagined universe does not titillate and reassure, it horrifies, it acknowledges a truth about the world or about the author, and the characters fight against it.
See also: James Watson. While describing Rosalind Franklin, possibly the discoverer of the structure of DNA, certainly the person who's crystallography skill made it possible: "In this new edition, I notice that Ray [Gosling - her student] has rather a good line in response to my comments about her appearance. He notes that I never saw her dressed up to go out in the evening, and that she had an elegance that I probably never saw." Watson, and I say this with perfect sincerity, go eat your own shit. What utter inability to perceive the greatness of one of our greatest scientists, just because it doesn't fit your gendered schema.
20 October 2012, 22:41 UTCThe technological woods
17 October 2012, 9:10 UTCCan't see the wood for the trees
2 October 2012, 11:59 UTCAnnouncing Demakein
23 September 2012, 0:13 UTCTalking to C++ for the incurably lazy
21 August 2012, 8:12 UTCMilling flutes
25 July 2012, 11:24 UTCPercarity and wealth inequality
8 July 2012, 0:28 UTCLessons learned
4 July 2012, 12:11 UTCReflections on "Revolutions in Reverse"
29 June 2012, 3:21 UTCNotes on Boswell's "Same-sex Unions in Premodern Europe"
28 May 2012, 11:24 UTCFlute on thingiverse
25 May 2012, 3:51 UTCArchitectural patterns that would also make great band names
16 May 2012, 0:07 UTCClothing rule of thumb
30 April 2012, 0:02 UTCDomain specific python
21 April 2012, 7:46 UTCLords and ladies
11 April 2012, 10:14 UTCMorality in animals
5 April 2012, 13:01 UTCWall of Sound
5 March 2012, 22:59 UTCEconomics zero
24 January 2012, 0:14 UTCPanopticon Australia
3 January 2012, 13:50 UTCThree ways to singularity
20 December 2011, 15:34 UTC"overcoming poverty is not a gesture of charity it is an act of justice"