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Below are the 20 most recent journal entries recorded in
Alan's LiveJournal:
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| Friday, June 19th, 2009 | | 12:22 am |
| | 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 |
| | 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.
- More to come soon!
- 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.
     FREQUENTLY ASKED QUESTIONS AND SUGGESTIONS - Can you melt glass?
Nope. Traditional glass is silicon dioxide, which melts around 1996 K. We can't melt copper at 1356 K, so we have no hope of melting actual glass. However, many things called "glass" these days are made out of other stuff (such as plastic, in the case of car windows), but these materials are clear and therefore doesn't absorb much light (so they won't heat up much if you shine light on them). Edit: maybe. Several people have commented that they have successfully achieved much higher temperatures using a similar lens. We now wonder if our metal holders (skillet, aluminum foil, etc) acted as a heat sink; we are looking into getting a ceramic crucible to see if we can get hotter temperatures. - Can you melt sand?
Nope. Sand is typically silicon dioxide. See question 1. - 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. - 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. - How much did the lens cost?
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. - 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. - 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). - 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 lensers ) On to the results! ( Pictures of new results )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! | | 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! | | Thursday, March 5th, 2009 | | 11:57 pm |
| | Sunday, March 1st, 2009 | | 3:15 pm |
The hawks are circling Iran again
What the crap is this!? Here are some of today's headlines: If you just glanced at today's headlines, would you think Iran was building a nuke and was likely to have it very soon? I certainly would. It's only after you read the articles that you find out the actual "story" is that Iran theoretically has enough uranium atoms to make a bomb but would first need to enrich them to become weapons grade, and they won't have the technical capability to do that for years to come. What the articles don't even mention is that the uranium is part of Iran's civilian power program, it's purified enough to be used in a nuclear power plant but not a bomb, Iran has signed the Nuclear Non-Proliferation Treaty under which it is given the inalienable right to civilian nuclear power but pledges not to pursue nuclear weapons, and the International Atomic Energy Agency has signed off on the whole program. What kind of bullshit is this!? This is not newsworthy and will only confuse people more about Iran. It's like saying that by living near the beach, I've amassed enough silicon to build my own computer from scratch (something I've thought would be cool to do for years: I want to start with raw materials and make a 2-function calculator or something). Except that when you get down to it, I'd still need to purify and dope the silicon, create transistors and then connect thousands of them in the right order to get anything close to the results I want. So, while it's technically true that I've got access to enough silicon, I'm actually still years away from results (and not actively working on it in the first place). It's a non-issue. It really irks me that the press picks up on this drivel while ignoring things like, say, the terrorist building a dirty bomb on US soil, which seems far more interesting, relevant, imminent, and dangerous (original source on page 11 of this leaked FBI document). Bruce Schneier suggests that this isn't pressworthy because the terrorist wasn't Muslim. Hooray, anti-Muslim bias in the media! To be fair, I've found three articles on Iran today whose headlines don't seem overly misleading: Reuters' Iran "not close" to nuclear weapon: Gates, Politico's Gates and Mullen disagree on Iran (which at least mentions that not everyone in government thinks Iran is getting a nuke tomorrow, though it does sow the seeds of doubt), and the Tehran Times' IAEA officials: All materials at Natanz under control (though honestly, no one is going to believe the Tehran Times if it's the minority dissenting voice about Iranian operations). and people wonder why I get so frustrated with the media. | | Sunday, February 22nd, 2009 | | 6:06 pm |
Will It Lens? Food Edition
If you missed it, here's part 1 and part 2 of our adventures with a 4'x3' fresnel lens. As always, I've got a gallery of all the raw pictures, and this is a summary of the good ones.
The same SAFETY NOTES as before apply, with the addition that you shouldn't eat any food you cooked in the same skillet in which you just cooked non-edible things (plastics, coins, etc). Also, we've upgraded our welding goggles, from a shade 5 filter to a shade 12, which is actually good enough that you can stare at stuff in the focal point. It's not quite good enough to stare directly at the sun, but it's darn close, and rumor has it that you can watch sunspots through this thing if you don't look at them too long. Last time, I left you with a picture of popcorn getting ready to be lensed. ( More results with more pictures )As always, remember safety first. Also, if you have more ideas of things we should try, I'm happy to give them a shot.  Edit: check out part 4 for more lensing fun! | | Friday, February 13th, 2009 | | 12:23 am |
Will It Lens? Part 2
In case you missed it, here's part 1 of our adventures with the 3'x4' fresnel lens. Oh, man. I have lots more pictures. The same SAFETY NOTE as last time applies again, but with a few more additions. You should probably wash your hands after you're done handling stuff in the lens. In particular, when you heat copper up until it turns black, you've probably made copper (II) oxide, which is a somewhat nasty irritant. I also make no guarantees about how many carcinogens we've made/touched/breathed, although so far I still feel healthy (no cancer in the past week!). Speaking of health hazards, if you use a frying pan to hold stuff, make sure it doesn't have a Teflon non-stick coating! That coating will burn away and become a huge safety hazard (it's mainly fluorine, and most fluorine compounds are toxic, volatile, and several other kinds of nasty; quite a few fluorine compounds were used as chemical weapons and precursors to sarin nerve gas, so avoid it at all costs). We got a cast-iron skillet, which is reasonably safe and inert, and it doesn't melt until we break 1800K, which is very unlikely with our current setup. Anyway, on to the results. ( with more pictures, of course. ) Until next time, make sure to have safety, fun and learning (in that order), and always remember that science is awesome! Edit: To find out what happens to the popcorn, check out part 3! | | Friday, February 6th, 2009 | | 8:01 pm |
| | Thursday, February 5th, 2009 | | 10:18 pm |
A new vulnerability in Java
Looking at Sun's take on it and Secunia's links, there's a fun little exploit in Java's calendar objects that can allow a remote user to obtain escalated privileges, allowing them to read, write, and execute any files on your computer that you have access to. The interesting thing about this bug is that it doesn't depend on memory being set up a certain way, which means it works reliably on a whole bunch of versions of Java, and in Mac, Windows, and *nix environments. You should update to the most recent version of Java to avoid this (see the Resolution section in the link to Sun above). Also, if you don't use Java applets on the web, you might consider disabling Java in your browser (for Firefox, it's under Edit > Preferences in the Content tab), so you don't need to worry about this (programs that you download and run manually are much less likely to have exploits than programs you might automatically start running from visiting the wrong website). | | Saturday, January 31st, 2009 | | 1:05 am |
Will It Lens?
A couple weeks ago, Dustin got a whole bunch of people to each contribute a few dollars, and we bought a four foot by three foot fresnel lens. It arrived earlier this week, and we've been spending our lunch hours out in the sun playing with it.  ( Explanation of the lens and safety note )( More pictures! )The next step is to build a wooden frame for the lens so it doesn't keep bending and screwing up the optics. We've talked about making a whole death ray setup, but I'm not sure we want a concentrated beam that extends indefinitely, because we could accidentally catch something important in it while setting up or taking down the device. We'll see what happens. In the meantime, if you have interesting ideas of things to lens (preferably things I can acquire that aren't too expensive and don't require much safety equipment), I'd love to hear them! Edit: check out part 2! | | Friday, January 16th, 2009 | | 12:26 am |
| | Thursday, January 1st, 2009 | | 11:08 pm |
Stand Back, I'm Going to Try Science!
My father is a chemical engineer at a large company. He volunteers in an outreach program where the company gives him science demonstrations aimed at precocious elementary schoolers, and he periodically goes to schools and birthday parties and stuff to show how neat science is. One of the kits he does is all about cryogenics, where he gets about a gallon of liquid nitrogen (LN2), and demonstrates what happens to things when you freeze them really cold. He talks about how matter can be a gas, a liquid, or a solid, and how its properties change as it goes from one state to another and changes temperature (racquetballs become brittle, flowers become crumbly, small amounts of LN2 boil into large amounts of nitrogen gas, etc). He did a demonstration a couple days ago, and still had some LN2 left over from it. Ordinarily he just pours the rest out on the street (it boils away quickly, and no one notices since air is already about 78% nitrogen). However, this time we convinced him to keep it around for a few days so we can try freezing other things. ( Some stuff about LN2, and some safety tips )Anyway, on to the results. ( With pictures! )I had a fantastic time playing with the liquid nitrogen, and I'm really glad I got pictures of most of what we did. If you ever get a chance to mess around with this stuff (chemistry majors, I'm looking at you), go for it!  | | Monday, December 29th, 2008 | | 11:47 am |
Getters and Setters aren't all they're cracked up to be
Allen Holub, author of Holub On Patterns, has an interesting article on how if you use getters and setters, you're probably doing it wrong.  His main claim is that getters and setters are a way of shoehorning procedural design into an object-oriented language, done by people who don't really understand the difference between a C-style struct and a class. He mentions a course taught in the '80s by Beck and Cunningham, in which they lament, "the most difficult problem in teaching object-oriented programming is getting the learner to give up the global knowledge of control that is possible with procedural programs, and rely on the local knowledge of objects to accomplish their tasks. Novice designs are littered with regressions to global thinking: gratuitous global variables, unnecessary pointers, and inappropriate reliance on the implementation of other objects." Holub talks about the CRC design model, in which Classes have Responsibilities and Collaborators. The idea is that the interface to a class should be a list of actions the class can do (its responsibilities) for the other classes it works with (its collaborators). In particular, the interface should not be a list of what data the class can store/retrieve for strangers (which is what getters/setters really are). Under this model, he claims that nearly all getters/setters can be removed in favor of functions that do the work you wanted for you, rather than giving you the info you need to do the work yourself.  ( Examples, motivations, and discussion ) | | Saturday, December 20th, 2008 | | 5:53 pm |
Interesting programming language: F#
Has anyone coded in F# before? It looks fantastic, but since it was created by Microsoft I don't expect a version I can use any time soon. but I like the way it describes and separates mutable and immutable data. I like the way it blends functional programming with object oriented stuff, and the way it is compatible with preexisting libraries written in other languages. I like the static type system and the type inference on top of it. It's got a lot of cool things reminiscent of SML (or OCaml, presumably, if I knew it better) while at the same time keeping an imperative, object-oriented spirit about it. I'm not wild about some of the syntax, particularly the way it's hard to tell where the definition of a type ends. and that weird <- operator for storing mutable data. and the bizarre [|...|] delimiters of arrays. and the whole #light declaration and how that totally changes syntax (just pick one way or the other and stick with the decision). But so far my biggest complaint is the syntax, while everything else about F# seems pretty cool. Has anyone actually played around with F#? I'd be interested in hearing how it works in practice.  | | Sunday, December 14th, 2008 | | 11:29 pm |
Our future is destroying our future
Automation is an awesome process. If you've ever taken a tour of a car factory, you know what I'm talking about. It's totally cool that we can build things that do our work for us. but if we keep this up, the entire economy will need to change. Those supercool robots you saw at the car assembly line? Each one replaced a person and destroyed a job. The self-checkout systems creeping into grocery stores are doing a similar thing by taking away jobs from checkout clerks. Now imagine someone makes an RFID-like checkout system that actually works (i.e. it doesn't have huge gaping security holes in it), and allows stores to replace all checkout people entirely. A similar system is already in place at my local library (complete with RFID security problems, but who's going to steal books that are loaned out for free anyway?), and as a result there are about half as many librarians who work there as there were 5 years ago. Suppose self-driving cars improve and become commonplace: there goes the job of every trucker, taxi driver, and garbageman. Taking that closer to the present, there already exist autonomous aircraft that can take off, fly, and land on their own with no human intervention. If that wasn't tied up in patent nightmares, I wonder if pilots would still have jobs. I'm surprised that trains/subways are still operated by people at all; I would have expected them to be completely automated years ago. and looking to the more distant future (though still probably within my lifetime), suppose a human-level AI is created. There go the jobs of everyone who thinks for their living (software engineers, accountants, actuaries, etc). and if we ever put such an AI in a mobile body, there goes everyone's jobs. Even without a human-level AI, things will change in major ways. Once automation starts being applied in all the places it can be, the world's job market will change drastically. Lots of occupations will no longer exist because they can be done more efficiently by machines than by people. and if nothing else changes before that happens, a lot of people will be out of jobs and in financial trouble. I hope we can find some way to head this crisis off before it happens, and either find new jobs for people or restructure the economy in such a way that all the out-of-work people aren't destitute. I've been kicking around some ideas on these topics, but I haven't come up with anything realistic yet. In particular, when a human-level AI is created, all of us will be out of work and all jobs will cease to exist. At that point, we really need to do something about the economy.  | | Wednesday, December 10th, 2008 | | 10:24 pm |
I know ![[info]](http://l-stat.livejournal.com/img/userinfo.gif) mikasaur2000 already posted this, but it's so fantastic I need to post it again. |
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