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Below are the 20 most recent journal entries recorded in Alan's LiveJournal:

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Friday, June 4th, 2010
4:23 am
Goodbye, Cruel LiveJournal
I figured I should break my silence to give a quick update of what's going on with this blog. I'm fed up with the crap that LiveJournal has been pulling recently, so I'm leaving and moving to my own website. The reasons to switch away from LJ have been mounting: reasons I no longer like LiveJournalCollapse )
Friday, February 5th, 2010
6:19 pm
Logic Puzzles vs. Hat Problem II
This is closer to the unsolved hat problem I have previously discussed than the solved hat problem I discussed. It made the rounds on a "Math Enthusiasts" mailing list I'm on today.

There are n people who have been given a challenge: tomorrow, a hat will be placed on each of their heads. There are n different colors of hats, and colors can be repeated (or not used at all). Everyone will be able to see the hats on everyone else's head but not their own. No one is allowed to communicate in any way while looking at each others hats. Then everyone is lead away into separate rooms and each person is asked the color of their own hat. If at least one person answers correctly, the group as a whole wins (unlike the unsolved hat problem mentioned above, no one is penalized for an incorrect guess). The people can discuss strategy amongst themselves before the challenge starts, but cannot communicate in any way once anyone gets a hat.

What strategy can they use to guarantee that the group wins?

and for the pedants out there: all participants are told all possible hat colors before the challenge starts (no need to guess what the unseen colors might be), and n is small enough that all colors can be distinguished on sight (it uses less than a million different shades of blue, for instance).
Tuesday, January 19th, 2010
6:19 pm
An Unexpected Annoyance
My car keys have an RFID chip in them, and my car has an RFID scanner that allows me to unlock the doors and drive the car without taking the keys out of my pocket. The transceiver in my new cell phone is strong enough that it jams the RFID communication when it's in the same pocket as my keys. I now need to get in the habit of keeping my keys and my phone in separate pockets. :-P

Edit: to be clear on the unexpected part, not only did I not foresee this issue, I'll wager that neither the RFID makers, nor the car designers, nor the phone designers considered this confluence, either.
Thursday, December 24th, 2009
9:16 pm
A fun web series
It revolves around Mr. Deity (creator of the universe), his assistant Larry, Jesse (also known as Jesus), and Lucy (short for Lucifer).

More episodes are at mrdeity.com, and extra stuff as well as a Seinfeldesque project they did are on their YouTube channel. Two of the YouTube episodes even feature Michael Shermer and PZ Meyers.

It's so strange to think that something this entertaining can be made by the same people that did the infamously bad Windows 7 video.
Saturday, December 19th, 2009
4:06 pm
Question for a physicist and/or chemist
I have some wild rice. The instructions on it say to boil some water in a saucepan, stir in the rice, cover, reduce heat to a simmer, and wait a while. When I stir the rice into the boiling water, I also stir in some butter and a spice mix (sugar, powdered soy sauce, onion, sesame seeds, garlic, and some other stuff). I mix everything thoroughly, cover it (so I can't see what happens), reduce the heat, and wait.

When the rice is done, I uncover it, and all the sesame seeds are in a ring around the edge of the pan. The ring is maybe an inch thick; the pan is about 8 inches in diameter. The butter and sugar are mixed throughout and not clustered in any place, but the other spices, like the sesame seeds, seem to be in higher concentrations in the ring and lower concentrations in the center of the pan. I have a gas-powered stove, if that makes a difference.

Why does this happen?
Monday, December 14th, 2009
10:54 pm
Science is Awesome: Speciation Happening Within Our Lifetimes
(found via the Skeptic's Guide to the Universe)

The short version: British bird enthusiasts have (unintentionally) split a population of birds into two separate groups, and over the past 50 years they have slowly but surely been turning into two separate species.

The long version (copied here for fear that the original article will disappear):
Article behind cutCollapse )
Friday, October 16th, 2009
3:21 am
Ligature Alternatives in LaTeX
I've been corresponding with Dario Taraborelli and Will Robertson, and we have concluded a couple things about LaTeX and alternative glyphs for ligatures: Don"t bother reading if you don"t use LaTeXCollapse ) So, I feel like I just leveled up in typography. Sure, this example is overly flowery to the point that the typesetting detracts from the poem itself, but it's more to illustrate a point than to make good typesetting. Note that I use two different glyphs for the 'ss' ligature, two different ones for 'ck', two different 'll's, and two different 'cl's. Also, I finally have a use for the dotless 'i' (in "Vine," my V of choice collided with the dot). Other fun typography tricks are scattered throughout, but they're more for my personal enjoyment than yours.
Thursday, September 24th, 2009
8:49 pm
Like XKCD for History Buffs
Take a look at Hark! A Vagrant:

She also has an LJ at beatonna.
Monday, September 14th, 2009
10:33 pm
Sunday, September 6th, 2009
5:36 pm
Reading the Canterbury Tales, old school
After my previous encounters with the Canterbury Tales, I've decided to read the entire thing. As before, I think that reading a modern translation loses the interesting parts of the language and screws up the poetry, so I want to read it in Middle English. and just because I can, I'm reading (a copy of) a 600-year old handwritten version. Those are images of the Hengwrt ("HENG-urt") manuscript, which was probably written sometime between 1400 and 1410 (note that Chaucer himself died in 1400, but it's hard to get closer to when he was alive). The images are very high quality; click the "all sizes" button towards the top to enlarge it a bit, then the "original resolution" link to see its true glory. I wish there was a way to set the default resolution higher, but I don't know if that's possible.

Sure, I could read a version with original spelling in a modern font, and towards the end I probably will. but for the moment, the novelty of reading a handwritten manuscript hasn't worn off, so I'm persisting. It took a bit of time to get the hang of the handwriting and grammar, so in the interests of helping others follow in my footsteps, here is an illustrated guide to reading the manuscript.

Letters and the AlphabetCollapse )
GrammarCollapse )
Spelling and VocabularyCollapse )
Further Tips and ResourcesCollapse )
If you have any further questions/suggestions, I'd be happy to answer them and add them above.

Now that you've got some idea what's going on, here are the first few lines to start you off:
The first few lines, with my own translationCollapse )
Thursday, August 20th, 2009
8:38 pm
C++ is bad: structs aren't the same as structs
Here's a fun little problem. Suppose you've got a system that makes use of the following struct:
struct User {
  unsigned int user_id;
  unsigned short access_level;
  float account_balance;  // stored as US dollars
Your system is ridiculously well-tested, all the tests pass, everything works totally fine. I'll be so bold as to say it's (kinda) bug-free.

One day, you decide to add a new field to the User struct, a string called name. You recompile everything, and suddenly all kinds of tests fail! New users have all kinds of access levels, some have account balances in the billions while others have accounts worth negative billions. What happened, why, and how do you fix it (without removing name again)? Edit: and no, the code does not rely on brittle assumptions about the value of sizeof(User), nor does it break type safety and have unsafe casts or void*'s pointing into the middle of Users. That would be too easy.

The answers, and more!Collapse )

Bonus question (independent of C++): storing the account_balance as a float (or even as a double!) is a terrible/dangerous idea; do you know why?
Monday, August 17th, 2009
9:37 pm
Oh, yes.

I don't care if it's old; it's new to me.
Friday, July 31st, 2009
11:04 pm
Will It Lens? Temperature Breakthrough!
In case you missed it, here are the other parts of the Will It Lens? series. I know I haven't updated in a while, and I've got a huge backlog of pictures. So, part will be discussed here and I already have enough for another post as well.

Remember that all the safety warnings from the other posts in the series still apply here, though I don't have anything new to add. Thanks for all the suggestions you've given us; we've tried some, and there have been quite a few good ones!

Improvements to our setupCollapse )Anyway, results. Take a guess what this is:

The answer, and more resultsCollapse )

I've got more pictures, but I'll save those for the next post.
Friday, June 19th, 2009
12:22 am
I just found a fantastic show
I totally prefer these dudes over Dawkins and Hitchens; they're great. Also, their stuff is released under the Creative Commons!

Full episodes (is that the right word for a talk show?) are available at atheist-experience.com.
Monday, June 15th, 2009
12:06 am
The photograph lies at my feet, falls from my fingers, is in my hand.
Dearest Internet, I write you today to share a discovery that excited my very being. I have found a wonderful connection between two ideas in which I merely dabble, and the way they complement each other so perfectly has given me new insight into both. The phrase "strawberries and cream" comes to mind. I am, of course, referring to quantum electrodynamics and video games.

If the complementarity is not immediately obvious, let me direct your attention to a particular video game, Braid. Oh, Internet, it is a marvelous game, full of challenge and fun! In the way that Portal is a puzzle game wherein you must manipulate space to solve the puzzles, Braid is a puzzle game wherein you manipulate time. Braid is also an homage to Super Mario Brothers, which gives it a nostalgic feel. But on top of the usual "go left," "go right," and "jump" commands, you have at your disposal a "rewind time" button that is your main tool throughout the game. You control a character named Tim, whose goal is to go from the door on the left of the level to the door on the right side, while solving any puzzles preventing this (yes, I am simplifying, but that's the important part for now).

Although the connection to QED may already be coming into focus, I should like to take a moment to remind you about the discipline. As you may recall, Internet, a man named Richard Feynman worked many a year on QED. He invented something called Feynman Diagrams, which are a very simple way to visually represent interactions between particles. He drew them as graphs with time along one axis and space along another, such as this:

In this image, the horizontal axis is time and the vertical axis is space. Depicted is one possible interaction between an electron and a photon. If one views time as monotonically moving forward (in the intuitive sense by which one normally perceives it), the photon coming down from the top spontaneously degenerates into an electron-positron pair (note that the positron is an anti-electron), and then the positron encounters the electron near the bottom of the diagram, and the two annihilate each other and turn into another photon.

However, there is another way to view this event. Anti-particles behave just like their (non-anti) counterparts moving backwards in time, since they have opposite charge and opposite spin but are otherwise identical. In other words, my good Internet, we could just as easily view this diagram as depicting an electron moving along the bottom of the diagram, then spontaneously "turning around" and moving backwards in time, while shooting off a photon as it reverses direction. It continues to move up the diagram, traveling backwards through time, and then spontaneously reverses its direction once more to travel forwards through time, sending out another photon as it does so. Although this photon gets sent backwards in time, we would perceive it normally because the photon is its own antiparticle (because it has no charge).

This reminded me quite strongly of certain levels in Braid, wherein time goes forwards as Tim moves to the right and backwards as he moves to the left. Here is an example, though it contains spoilers if you have not yet played the game. To give a better illustration of their similarity, consider the following diagram. Living things are in blue, photons are in red, and objects and platforms are in black.

If one were playing the game, one would see Tim come out of the door at the bottom left of the image, travel to the right (going forwards through time) until time E, then shoot out a photon, turn around, and jump up onto the platform (going backwards in time), jump over the Goomba at time B (Goombas can only be killed when going forwards through time). Tim would then turn around at time A (shooting a photon to the left in the process), jump forwards through time and land on the Goomba to kill it, then jump at time D to get to the platform with the door and exit the level.

If, instead, we needed to watch these events as time monotonically increased, we would observe a photon on the platform and a Tim on the floor. At time A, the photon spontaneously decays into a Tim-antiTim pair. The Tim jumps immediately, while a moment later the antiTim unjumps. At time B, a Goomba comes into existence and is killed by the descending Tim. The antiTim, meanwhile, is high above and dodges the event. At time C, the Tim and antiTim collide, annihilate each other and become a photon again, though this photon decays into another Tim-antiTim pair at time D. The Tim jumps and the antiTim unjumps. Then the platform winks out of existence, and the antiTim falls through the space where it used to be. At time E, the antiTim encounters the Tim from the floor, the two annihilate each other and become a photon. The platform materializes above, the remaining Tim lands on it and encounters the final door, finishing the level. When I first realized this, it was a very exciting connection for me. I imagine, dear Internet, that you now share my spark of insight.

If you desire to play Braid for yourself, it is available for download on XBox, Windows, and Mac. The demo is free, and the entire game is $15.
Sunday, May 3rd, 2009
6:46 pm
If the arctic ice cap melts...
...where would Christians tell their children that Santa's workshop is located?
Monday, April 20th, 2009
2:37 am
Thursday, April 9th, 2009
12:54 pm
Will It Lens? Table of Contents

Welcome, all! Here are links to everything in the "Will It Lens?" series.
  • Part 1: introduction, melting pennies, dimes, toothpaste, Tylenol, milk, chalk, gourd, can.
  • Part 2: equipment upgrades, CDs, disposable silverware, brass penny, burned pennies.
  • Part 3 (Food Edition): popcorn, grape, kumquat, Frosted Mini Wheat, jelly beans, Reese's Pieces.
  • Part 4: wood, quarter, soap, dishwasher detergent, bacon, egg, honey, seashell, almonds, gummy bears, M&Ms.
  • Part 5 (Temperature Breakthrough): marshmallow, peeps, copper, iron, sand, glass
  • More to come soon eventually!
  • Gallery of all pictures: This contains every picture we took. There's a lot of junk in here; the good pictures are in the blog posts above.

  1. Can you melt glass?

    This surprised us, but yes! Normal glass is more properly called "sodalime glass," which has a much lower melting point than pure silicon dioxide (which we originally thought glass was made of, and which we haven't been able to melt yet). However, we have trouble melting clear things because they don't absorb the sunlight. Nonetheless, we melted a dark brown glass in part 5.

  2. Can you melt sand?

    Kinda. The sand we tried is a mixture of quartz, feldspar, and iron. We can melt the last two, but we haven't melted quartz yet. Look at part 5 for more details.

  3. Can you lens electronics?

    We probably could, but we don't want to because the fumes are really noxious. There's lead and other stuff that's terrible for your lungs in there.

  4. Can you use a second lens to focus the light even more?

    No, that's not how optics works. For a slightly more thorough answer, see the Light Sharpener FAQ over at cockeyed.com.

  5. Where did you get the lens? How much did it cost?

    I think we got it from here. When we ordered it, I think it was about $120, plus shipping. If you include the wood for the frame and stand, the welding goggles, and the skillet, we've probably spent over $200 on lens-related stuff so far.

  6. You should lens something that will burst and explode all over the place!

    That would be very entertaining, but we need to clean everything up before lunch is over, so we're not doing anything too messy in the foreseeable future (no unopened pop cans, no aerosols, etc.). If we ever take the lens out to the middle of the desert, we will consider lensing messy things.

  7. You should lens an iPhone, iPod, or other hip status symbol.

    First, see question 3 about electronics. Then, remember that we're paying for all of this with our own money. We'd prefer not to lens anything that costs more than a couple dollars. Everything we've tried so far has cost under $1 each (almost everything is under $0.25 each).

  8. Isn't it illegal to destroy money?

    Not unless you do it with the intent to defraud someone. Remember the last time you went to the zoo? You probably saw one of those machines that will take your penny, flatten it out, and stamp an image of a penguin or something on it as a souvenir. Melting a penny is no more illegal than one of those machines.

Other articles that link to this series:
Saturday, April 4th, 2009
11:28 pm
Will It Lens? Part 4
If you've missed it, here are parts one, two, and three of our adventures with a 4'x3' fresnel lens, along with a gallery of all the pictures.

Our lens arrived with a corner chipped off, so the lens company sent us a second one for free (which also had its corner chipped off on arrival, but we didn't get a third for free). I've been holding off writing this post because I was hoping to title it "Episode IV: A New Lens," but we still haven't built the frame for the second lens or the frame for the mirrors that will reflect light from both lenses onto a single point. So, instead of waiting for that to happen, I'm posting the results I've already got.

The same SAFETY NOTES as before apply, as always. In lieu of new safety warnings (we haven't had any new dangers come up!), I've got a few tips for anyone trying to duplicate this. Some tips for fellow lensersCollapse ) On to the results!

Pictures of new resultsCollapse )

As always, if you have ideas of stuff to lens, I'd be happy to try them out. Until next time, be safe and have fun!

Edit: In part 5 we achieve much higher temperatures!
Thursday, March 12th, 2009
10:31 pm
Mother of All Funk Chords
Oh man, this is awesome! and as icing on the cake, the creator cites all of his sources!

This is why current "IP" rights need to swing further towards fair use: so you can do this sort of awesomeness. The kid with the trumpet just played a scale; the real value here was added by the remixer, and I think it's bullshit that legally, that trumpet player could send a DMCA takedown notice for this. To the best of my knowledge, the trumpeter has no such intentions; I'm just making a hypothetical here.

Hopefully this sort of remixing will convince the musicians who don't get it yet that it's important to allow everyone to have fair use rights. Damn this stuff is sweet!
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