xkcd

After a hectic few months, I finally have some projects that are in the early stages.  But since nothing is worth posting about yet, here instead is a list of phrases that (at the time of this posting) turn up no hits on Google:

• “ate a violin”
• “driver-side bidet”
• “unlike normal furries,”
• “Sarah, plain and tall and a cyborg”
• “people are too civil on the internet”
• “his penis shattered my world”
• “more like LAME-arkian theory”
• “my little horse must think it gay”
• “it turned out her bottom half was a robot”
• “Aww, a baby hooker!”

Here are some phrases that I had hoped were original when I typed them in but was disappointed:

• “full-body glissando”
• “passenger-side bidet”
• “underwater Linux”
• “Nu-Polka”
• “erotic colonoscopy”
• “Spocktoberfest”
• “Frankly, my dear, I don’t give a frack.”
• “my bologna has a first name, it’s A-D-O-L-F”

And lastly, here’s a fun bash export I stumbled on:

• export PS1='C:${PWD//\//\\\}>'

I am currently at the tail end of the Debate Drinking Game, wherein you take a drink every time McCain says “my friends” and Obama starts a response with “Look,”.   Since both candidates had their verbal tics under control, I just took a drink every time someone said a pronoun.  I am not in a good state.  Fortunately Google’s sobriety test has not yet extended to the WordPress default implementation.   Why would you ask for the arctan of pi/2?  Maybe it will make sense when I’m sober.

I did an interview with the New Yorker Cartoon Blog.  It’s available here.

I will be in Burlington, Vermont tomorrow, to try kite photography.  Thanks to the excellent (albeit poorly-organized) CHDK project, I’ve picked up a cheap Canon Powershot A720 and modified it to do time-lapse photography.  This makes kite photography much simpler than it’s been in the past.

If there are any readers in the Burlington area who are interested in kite flying and know of a good location, email me at xkcd@xkcd.com.  I will send out an email containing plans to anyone who contacts me, sometime soon after noon.  If you know someone in Burlington (e.g. at UVm,) let them know!  Thanks.

Wow. It seems someone at YouTUBE took this comic seriously and decided to add an “Audio Preview” feature. Now you can hear your comments read aloud to you.

Of course, it’s an optional button using speech synth rather than a mandatory dramatic reading, so it’ll just be used for entertainment by people who haven’t played with a speech synthesizer before:

But then, after a little more browsing around, I see this:

So maybe there’s hope after all.

(Written after sitting in a car for five hours listening to financial news stories.)

——-

Damn these subprime lenders, thought Fed Chairman Ben Bernanke, barely keeping his balance on the wobbling skateboard. We can’t afford more debt. He snapped a grappling-hook-tipped quarrel into his crossbow as the skateboard slowed. When the country owes trillions and is asking for more, its shadowy creditors start calling in favors.

The crossbow twanged, carrying his climbing rope up the side of the Federal Reserve building. As he began his ascent, he reflected on the years past. I inherited a broken system, he insisted to himself. We’re simply doing what’s required to prevent a catastrophe. It’s not my fault.

He tossed his skateboard over the parapet and hauled himself over. He dropped six feet to the roof, landed heavily on the board, and trundled on into the night.

——-

From her perch in a tree across the street, the blogger watched through her blogoscope as Bernanke disappeared over the wall. She spoke quietly into her radio: “Subject is in the haybarn. The chickens are in danger of roosting.”

“Roger that,” came the reply. “Deploying Agent Harpsichord.”

——-

Inside, Bernanke moved along the wall like a shadow, elongating and contracting as the light sources shifted around him. In the midst of a sea of filing cabinets, he froze. He sniffed the air, then dropped to his knees, licked the floor, and paused. Yes, he thought, Greenspan was definitely here.

——-

The blogger had waited five minutes and was starting to get impatient. She picked up the radio. “Situation imminent. Pass the ducklings through the snorkel. Repeat: Pass the ducklings through the snorkel.”

“We are go for mode Sinatra,” replied the commander. “Reticulate core and set throttle to ‘cryptic’. Prepare to jitterbug.”

——-

Bernanke forced the door on yet another inner office, realizing too late that the light was on inside. The chair in the corner swiveled around, and Bernanke found himself face-to-face with Alan Greenspan. There was silence for a moment.

“You won’t get away with this,” said Greenspan, rising to his feet. “The Fed is subject to general congressional oversight. But you never understood that, did you?”

“Congress sold out the country, not me,” replied Bernanke. “Don’t shoot the messenger.”

“I wasn’t planning to,” said Greenspan. He flicked open a switchblade.

——-

The blogger peered once more into the eyepiece of her blogoscope. She threw the switch labeled “overlay building schematics.” The external view of the building disappeared, but instead of blueprints, she was presented with a green puzzle piece. “This view requires the Adobe Flash Player plug-in. Do you want to search for this plug-in now?”

Shit, she thought.

——-

Bernanke, trying not to slip in the patches of blood on the floor, struggled with Greenspan. The older man moved like a snake that moved like a former Fed Chairman who moved like a ninja. At last, Bernanke got a solid grip on Greenspan’s collar and hurled him through the fourth wall, knocking you to the ground.

Improvising a tourniquet from the remains of the snake left over from the earlier simile, Bernanke moved on through the hallways.

——-

The moonlight-bathed roof of the Federal Reserve building fell suddenly into shadow. A pair of night watchman looked up in alarm to see what had occluded the sky.

“Is that …” one whispered to the other, “… is that a blimp?”

——-

Bernanke reached the central vaults, accessed the Gibson mainframe, and began transmitting the requested files to his distant masters. He didn’t hear the gentle thud on the rooftop, the muffled explosive charges, or the sound of the door opening behind him. But at the last minute some sixth sense kicked in. He spun around just in time to see a golf-ball-sized lump of gold rapidly expanding in his vision. It struck him in the forehead, and he collapsed to the ground like a burlap sack full of scrapple.

Congressman Ron Paul retrieved the gold nugget from the floor and returned it to his satchel. “Try that,” he said, donning his sunglasses, “with a fiat currency.” He spun on his heel, cape swirling behind him, and swept from the room.

Read more of these adventures in the thrilling new novel, Ron Paul and the Chamber of Commerce — in bookstores now!

Sorry for the forum/blog downtime today. Many things went wrong during davean’s heroic upgrade. (I blame the LHC.)

Feynman used to tell a story about a simple lawn-sprinkler physics problem. The nifty thing about the problem was that the answer was immediately obvious, but to some people it was immediately obvious one way and to some it was immediately obvious the other. (For the record, the answer to Feynman problem, which he never tells you in his book, was that the sprinkler doesn’t move at all. Moreover, he only brought it up to start an argument to act as a diversion while he seduced your mother in the other room.)

The airplane/treadmill problem is similar. It contains a basic ambiguity, and people resolve it one of a couple different ways. The tricky thing is, each group thinks the other is making a very simple physics mistake. So you get two groups each condescendingly explaining basic physics and math to the other. This is why, for example, the airplane/treadmill problem is a banned topic on the xkcd forums (along with argument about whether 0.999… = 1).

The problem is as follows:

Imagine a 747 is sitting on a conveyor belt, as wide and long as a runway. The conveyor belt is designed to exactly match the speed of the wheels, moving in the opposite direction. Can the plane take off?

The practical answer is “yes”. A 747’s engines produce a quarter of a million pounds of thrust. That is, each engine is powerful enough to launch a brachiosaurus straight up (see diagram). With that kind of force, no matter what’s happening to the treadmill and wheels, the plane is going to move forward and take off.

But there’s a problem. Let’s take a look at the statement “The conveyor belt is designed to exactly match the speed of the wheels”. What does that mean?

Well, as I see it, there are three possible interpretations.  Let’s consider each one based on this diagram:

1. v_B=v_C: The belt always moves at the same speed as the bottom of the wheel. This is always true if the wheels aren’t sliding, and could simply describe a treadmill with no motor. I haven’t seen many people subscribe to this interpretation.

2. v_C=v_W: That is, if the axle is moving forward (relative to the ground, not the treadmill) at 5 m/s, the treadmill moves backward at 5 m/s. This is physically plausible. All it means is that the wheels will spin twice as fast as normal, but that won’t stop the plane from taking off. People who subscribe to this interpretation tend to assume the people who disagree with them think airplanes are powered by their wheels.

3. v_C=v_W+v_B: What if we hook up a speedometer to the wheel, and make the treadmill spin backward as fast as the speedometer says the plane is going forward? Then the “speedometer speed” would be v_W+v_B — the relative speed of the wheel over the treadmill. This is, for example, how a car-on–a-treadmill setup would work. This is the assumption that most of the ’stationary plane’ people subscribe to. The problem with this is that it’s an ill-defined system. For non-slip tires, v_B=v_C. So v_C=v_W+v_C. If we make v_W positive, there is no value v_C can take to make the equation true. (For those stubbornly clinging to vestiges of reality, in a system where the treadmill responds via a PID controller, the result would be the treadmill quickly spinning up to infinity.) So, in this system, the plane cannot have a nonzero speed. (We’ll call this the “JetBlue” scenario.)

But if we push with the engines, what happens? The terms of the problem tell us that the plane cannot have a nonzero speed, but there’s no physical mechanism that would plausibly make this happen. The treadmill could spin the wheels, but the acceleration would destroy them before it stopped the plane. The problem is basically asking “what happens if you take a plane that can’t move and move it?” It might intrigue literary critics, but it’s a poor physics question.

So, people who go with interpretation #3 notice immediately that the plane cannot move and keep trying to condescendingly explain to the #2 crowd that nothing they say changes the basic facts of the problem. The #2 crowd is busy explaining to the #3 crowd that planes aren’t driven by their wheels. Of course, this being the internet, there’s also a #4 crowd loudly arguing that even if the plane was able to move, it couldn’t have been what hit the Pentagon.

All in all, it’s a lovely recipe for an internet argument, and it’s been had too many times. So let’s see if we can avoid that. I suggest posting stories about something that happened to you recently, and post nice things about other peoples’ stories. If you’re desperate to tell me that I’m wrong on the internet, don’t bother. I’ve snuck onto the plane into first class with the #5 crowd and we’re busy finding out how many cocktails they’ll serve while we’re waiting for the treadmill to start. God help us if, after the fourth round of drinks, someone brings up the two envelopes paradox.

Pi-Con: This weekend I’ll be at Pi-Con, a convention in West Springfield, MA.  It’s run by some old friends of mine, and will feature Cory Doctorow.  I’ve never actually met Mr. Doctorow in person, so it should be fun.  In my mind’s eye, he still wears a red cape and goggles everywhere he goes.  I hope that’s okay with him.  Anyway, feel free to stop by!  You don’t need to pre-register or anything.

I’ll be spending most of my time there on panels.  It still baffles me that sometimes I’m put on panels to talk about serious business.  A convention once saw, for example, that I had worked at NASA, and put me on a panel about the future of space exploration.  I felt a little out-of-place, given that my main NASA achievement was that I once lassoed a robot with cat-6 cable and had it pull me around the hallways charioteer-style.  So I sit, surrounded by Ph. Ds, and look thoughtful while drawing stick figures on convention stationery.

Project Euler: As is my habit lately when I travel, I’ll probably be working on Project Euler.  For those unfamiliar, Project Euler is a site with a lot of math-oriented programming problems that you can solve in any language.  They start out easy (First problem: Find the sum of all the multiples of 3 or 5 below 1000.)  Then they get harder rather quickly.  I think it’s a great way to learn a language; I started picking up Python last year by doing the first couple dozen Project Euler problems in it.  Many of the problems lend themselves to clever recursive solutions, and as such I imagine it’d be a great way to learn Lisp.

Book recommendation: Self-Made Man, by Norah Vincent.  I inhaled this book in practically one sitting, as did my cousin and several other friends.  In it, the author passes as a man for a year to try to understand the male world, taking notes the whole way.  It’s full of fascinating little stories and avoids getting too preachy — just shows over and over again the surprising ways in which gender influences basic social stuff.  Thanks to creature of #xkcd for first sending me a copy.

Notice: Whoever’s been sending me periodic text messages, formatted like official VP announcements, telling me that Obama has selected Summer Glau as his running mate, please stop.  You get my hopes up every time.

In today’s comic, I have the rain-stick thing happening in Jaynestown, when it actually happens in Our Mrs. Reynolds.  I lose three nerd points.

When writing the comic, I actually compiled a list of references to wood in Firefly by searching the scripts. They included Badger serving Jayne wood alcohol and Inara likening Mal’s sword technique to ‘chopping wood’ (both in Shindig). I should put it on Wikipedia so nobody has to duplicate my efforts.

Note: I actually wrote this post from the road early this morning to try to stave off the subsequent flood of email, but in my sleepiness I accidentally published it as a “page” instead of a “post” (a Wordpress distinction that’s confused me before). So, all told, this was not a good day for my internet skills.  I think I’ve dropped from 1337 to 1334, maybe 1335 tops.

A while back, I was home in Virginia for a little while, and my friend James decided it was time to build a trebuchet

Pictured: James, Doug

I say measure once, cut eighty or ninety times.

As you can see by Doug’s hat, trebuchets are very serious business.

I had to leave before we could test it, but they finished up the last touches in my absence. This week, we got a chance to fire it for the first time.

The projectile (three full Dr Pepper cans taped together) vanished off into the woods. Firing successful! In the video, you can see falling leaves cut by the projectile.

In other news, Geohashing is working out wonderfully. At the most recent meetup I attended, we flew a camera from a kite and then tried to spell words under it.

There’s a new feature in the map-locating program where you can suggest and vote on alternate meetup sites for a given day. So far, the pattern is generally that we show up at the location, then find a nearby park or restaurant to hang out at. Bringing games and activities is encouraged.

I wasn’t able to make it to the most recent meetup because I was at MoCCA. By the way — thank you to Chris Hastings of Dr. McNinja for his generous hospitality. He gave me a place to sleep with no advance warning and didn’t even get mad when I spent the night sick on his couch, beat him at Mario Kart, and stole half his stuff. (If anyone wants a good deal on some of his erotic Batman fan art, let me know.)

This afternoon (starting 4:00-ish), some friends and I are heading to Belle Island in Richmond, VA, which is an alternate location for today’s geohash. I hear there are fireworks or something?

Geohashing has been great fun so far. There are hundreds of users on the wiki, and I’ve gotten to wander places like this:

There’s been a small change to the algorithm to deal with time zones. This change does not affect anyone in North/South America (excluding Greenland), does not affect Saturday meetup times anywhere, and does not change any currently known upcoming meeting times. The change:

For every location east of Longitude -30 (Europe, Africa, Asia, and Australia), use the Dow opening from the previous day — even if a new one becomes available partway through the day.

Put differently (the same functionally for everywhere except islands in the mid-Atlantic):

Consider any Dow openings published after noon local time to have occurred on the next day.

This is necessary to deal with time zone problems. For a lot of Europe, the Wednesday Dow opening was learned near sundown Wednesday, which meant they couldn’t use it to get to daytime meetups. For east Asia, they had to visit weekday locations the next day. A bunch of solutions were discussed, and I decided this was the cleanest.

The official map tool is being updated with the new behavior concurrently with this blog entry. The first coordinates that will be affected by it are Tuesday’s. Again, this does not affect anyone in the Americas.

Moving on — Saturday’s meetups are looking good! Today’s location in Boston was fantastic. I wasn’t planning to go, but it looked so interesting on Google Maps that we couldn’t resist checking it out. The picture above is one of several. Saturday’s meetup is in a less picturesque place than Friday or Sunday — suburban Hopewell. We’ll probably gather only briefly at the actual point, then head to the nearby state forest for walking or town center for food and such.

Also, good luck to phire, who was last seen on IRC an hour ago, leaving to mountain-climb to today’s coordinates in Christchurch, New Zealand. Congrats to the Denver graticules for getting organized so fast (and in a split city, at that!). And thanks to everyone for going along with this idea! The weekday trips have been great fun so far, and I look forward to getting the meetups going over the next few weekends!

Summer seems to have arrived, at last.

As you may have noticed, today’s comic contains an algorithm for converting dates into local coordinates. For a given day, you can calculate what that day’s coordinate is for your region. Dan has put together a tool for calculating a day’s coordinates and show it using Google Maps. Note that you can’t calculate a day’s coordinates before the stock market opens on that day (about 9:00 EST) — except for weekends and holidays, when it uses the most recent opening price.

We’ve been having fun trying to reach these coordinates for some time now, when the coordinate is reachable — that is, when it’s not over water, in a military base, or in the middle of Bill Gates’s house.

If you happen to be looking for somewhere to go, driving to the coordinates can be an adventure. If you do, please take pictures and drop them on the geohashing wiki (feel free to help fill it out).  I’m gonna get some rest and then, at 10 AM tomorrow, see if I can get to the Boston coordinates (I have no way of knowing where they’ll be until then, of course).

And finally, when the coordinates are reachable, meetups are Saturday afternoon at 4:00.

Edit: I answered a bunch of questions in a comment below.  Further discussion is also happening on the wiki. I’m going to get some sleep and then head out to today’s coordinates (or as close as I can get).