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|Friday, September 10th, 2010|
|Bye bye apartment. Hello house.
On my way out. Bye to my nice, super-convenient apartment and my chain-smoking neighbors. (Some of which were fun.)
Hello lawn I'm already killing and kitchen that I have converted into a health hazard.
|Tuesday, July 6th, 2010|
In the last 24 hours I've worked a little less than half the number of hours I worked last week. Unfortunately, the latter number was a little less than 50.
|Saturday, July 3rd, 2010|
|Arthur Lee Eastin
Many of you have already heard, but for those who haven't, here's a copy of the announcement:
I am writing to announce the birth of Arthur Lee Eastin at 6:54am on Saturday the 26th of June, 2010. Florence's water broke on Thursday night, and after 33 hours of labor, she managed to push him out in about 20 minutes. Arthur was 6 pounds and 11 ounces at birth and 21 inches long. To date, his most notable personality trait is a tendency to snort. (He began life with meconium in his lungs.) [Update: He's more in to vomit now.] Arthur and Florence are doing fine, and I have declared him a sweet baby.
See Facebook for photos.
|Sunday, February 14th, 2010|
I am still writing my newest paper. It seems that I can do that forever. Apropos, here is a story about LaTeX.
I desperately wanted the \bigominus symbol. Sadly, \bigominus was not in my league, that is, it was not among the AMS math symbols. I could get \bigominus by loading the MnSymbol package, but that would entail replacing all of my AMS-math-symbol friends with new, uglier MnSymbol versions. I was determined to have \bigominus alone, however, so I temporarily used the MnSymbol package and consulted with pifont (which turned out to be a member of PSNFSS [the LaTeX installation]) about the exact location of \bigominus. After many hours of trying, I discovered the secret to getting \bigominus in MnSymbol.sty. I just needed to
So I did, and now I have \bigominus.
|Friday, October 9th, 2009|
|Saturday, September 5th, 2009|
|Capitol Hill Baby-Sitting Co-op
This co-op, whose problems were recounted in a 1977 article in The Journal of Money, Credit and Banking, was an association of about 150 young couples who agreed to help one another by baby-sitting for one another’s children when parents wanted a night out. To ensure that every couple did its fair share of baby-sitting, the co-op introduced a form of scrip: coupons made out of heavy pieces of paper, each entitling the bearer to one half-hour of sitting time. Initially, members received 20 coupons on joining and were required to return the same amount on departing the group.
Unfortunately, it turned out that the co-op’s members, on average, wanted to hold a reserve of more than 20 coupons, perhaps, in case they should want to go out several times in a row. As a result, relatively few people wanted to spend their scrip and go out, while many wanted to baby-sit so they could add to their hoard. But since baby-sitting opportunities arise only when someone goes out for the night, this meant that baby-sitting jobs were hard to find, which made members of the co-op even more reluctant to go out, making baby-sitting jobs even scarcer. . . .
In short, the co-op fell into a recession.
(From a very interesting article by Paul Krugman at the New York Times, How Did Economists Get It So Wrong?
. Apparently, neoclassical economists [the efficient market folks] would expect this never to happen; instead, the value of baby-sitting scrip should have inflated.)
|Tuesday, June 23rd, 2009|
Today I found out that a good friend of mine has died. I hadn't been doing a very good job of keeping in touch lately. I didn't know that she dropped out of grad school last month. She was depressed, and I'm pretty sure she committed suicide.
There are so many things that I wish I could do differently. I wouldn't have to go back very far, just a little more than a month.
|Saturday, May 9th, 2009|
|Life, the universe, and everything
A friend of mine's father is struggling with aggressive cancer. In spite of fair warning, she asked what my view on life and religion is. I felt like the reply might be interesting to my other friends, so I have included it below verbatim.
Okay. I feel compelled to start out by saying that I don't always live up to my principles. However, to the best of my introspective ability this morning, the following is what I think about life, the universe, and everything.
I believe that the universe just is. There exists matter and energy and physical laws. There exists cause and effect. But there is no meaning, no purpose, and no deeper reason. Justice and compassion and love are abstractions of thinking beings. To demand such ideals from the universe is as to demand them from a stone or a knife or a gun.
I believe that all things are imperfect and that all things ultimately pass away. Perfection is not just an unreachable ideal; it is a meaningless one for all but the most limited definitions of perfect. Which is more perfect, the tortoise or the dolphin? All strengths are also flaws. The flaw of life is that it must die, or, at least, change. Life acts and reacts. What would it mean to be an eternal being? If you lived ten million years, truly lived, would you be the same person that you are now? Are you the same person that you were when you learned to speak? Not only men but the marks of men pass away, time is change. In time we are all forgotten.
I believe that in these ideas are some seeds of comfort.
All things pass away, but this is true both for both the good and the bad. There is no benevolence nor atrocity so great that time will not wash it away. The world is ever reborn. If to die is to lose the game of life then we all lose. You can play the game with joy and style or not, but, really, if there is no way to win then there is also no way to lose. Don't be afraid.
Nothing is perfect, so you don't need to be perfect. There is no such thing as a perfect person. Improving yourself in one way necessarily entails forgoing another, and some “improvements” are outright contradictory. An extraordinary weight lifter is not an extraordinary runner. Life is about figuring out how much time and effort you wish to spend on disparate goals. You will probably be very far from the best at most things. That is okay and to be expected. Achieve what you can in those areas that most interest you. Do your best, but don't worry.
Those ideals, such as justice, which humans value most highly are not intrinsic to the world. They are not enforced by nature nor by any higher power. Men can and often do act against these ideals without being punished for their actions. Many ideals are also contrary to self interest. And yet, if we cherish some ideal then we can seek to make it a reality. We can work for justice and liberty and the common good. We can strive to be honest and loving and courageous. And what better justification could we have for our existence? Mankind is more valuable than any of those ideas because they exist only through him. Follow your ideals.
There is no god. No higher being will save you, but none will torment you either. The universe isn't cheering for you, but it's also not out to get you. Frankly, it's oblivious, insensate. The path of your life is a mixture of your own actions, the actions of others, and impersonal physical processes. When you suffer at the hands of chance, take solace in the fact that it was only that. Bad things happen to good people, not because deep down there was something wrong with them or because they've angered a vengeful god but because there is no plan behind existence. Don't take it personally; press on.
|Monday, May 4th, 2009|
|Condoleezza Rice on torture
Somehow I feel that the phrase
“When the president does it, that means that it is not illegal.” ought to send shivers down the spine of any American, regardless of political creed. Is there some implied technical argument about the Geneva convention that I'm missing here?
|Thursday, December 18th, 2008|
|Your Quotes for Today
At the end of the evening someone turned to the brilliant Wolfgang Pauli and said, "You have been very quiet tonight, Pauli. What do you think of what Dirac has been telling us?" Pauli responded, "If I understand Dirac correctly, his meaning is this: there is no God, and Dirac is his Prophet."
The closer to the truth, the better the lie, and the truth itself, when it can be used, is the best lie.
- Isaac Asimov
If we knew what it was we were doing, it would not be called research, would it?
- Albert Einstein
|Tuesday, September 30th, 2008|
|Your Quotes for Today
I am an atheist, out and out. It took me a long time to say it. I've been an atheist for years and years, but somehow I felt it was intellectually unrespectable to say that one is an atheist, because it assumed knowledge that one didn't have. Somehow it was better to say one was a humanist or agnostic. I don't have the evidence to prove that God doesn't exist, but I so strongly suspect that he doesn't that I don't want to waste my time.
- Isaac Asimov
The whole problem with the world is that fools and fanatics are always so certain of themselves, but wiser people so full of doubts.
- Bertrand Russell
You know the watch argument was Paley's greatest effort. A man finds a watch and it is so wonderful that he concludes that it must have had a maker. He finds the maker and he is so much more wonderful than the watch that he says he must have had a maker. Then he finds God, the maker of the man, and he is so much more wonderful than the man that he could not have had a maker. This is what the lawyers call a departure in pleading.
- Robert Green Ingersoll
|Thursday, June 19th, 2008|
|Scientific papers and community generated errata
I painstakingly verified equation 38 in the paper "Exact performance of concatenated quantum codes" by Benjamin Rahn, Andrew Doherty, and Hideo Mabuchi. I found that it was correct, but that the result they give which specializes the equation to X errors was wrong.
I feel that I should be able to post this information somewhere to save future researchers the trouble, but there does not appear to be any way for me, the reader, to note minor errata. I am surprised that this is the case. It could be as easy as adding a comments section to either publisher or preprint websites.
|Saturday, June 7th, 2008|
|Magnetic catapults: Orbital insertion and arrogance
I ran across a neat article this afternoon (so many hours ago) about a variant on the super-conducting coil gun as a method of launching materials (people wouldn't survive) into space. Basically, the idea is to instill a current in the individual coils such that the resultant magnetic field (and consequently the current) is just canceled when the projectile (which carries it's own magnetic field) is in the middle of the a coil; at that instant you switch off the coil, thereby avoiding energy loss and serious switching and heating problems. The preparation is arranged by placing the projectile in the coil at the end of the launcher (with the projectile's magnetic field already in place), cooling that coil till it becomes superconducting, winching the projectile backwards to the next coil, and repeating. Superconducting rings trap magnetic field lines, so, as the projectile is removed, a current is generated in each coil maintaining the magnetic flux. Since it is in a superconductor, the current will stick around. No energy storage mechanism beyond the coils in the launcher is required. To fire the gun you let the projectile go at the front end and break the electrical connection for each coil as it passes. The projectile gets sucked into each coil successively. The paper spends a lot of time on the tricky parts, finding superconductors with the right properties and breaking the connection in a non-destructive fashion.
You can find the article, written by Warren Smith, at http://www.math.temple.edu/~wds/homepage/launcher.ps
Though I didn't check every equation and every listed material property, I read the paper with some care, and I was impressed with the level detail and (so far as I can tell and ignoring a few obvious typos) accuracy. Unfortunately, Dr. Smith only grudgingly acknowledges anyone (you'd almost think he invented the coil gun) and generally dishes out a lot of unnecessary vitriol. Ironically, I just found out that he is also one of the founders of the primary website advocating range voting, and I've been reading a lot of discussions of voting methods lately that suffer from the same problem.
I'm really impressed by this guy, but I'd be a lot more impressed if he wasn't such a jerk.
Anyhow, here are some entertaining details of the proposal: The launcher is a 9 km long evacuated tube lined with superconducting coils and cooled to at least liquid nitrogen temperatures. The launcher exits from the peak of one of the tallest mountains on earth so as to avoid as much atmosphere as possible. The force experienced by the cargo is estimated at roughly 2000 g's. The cost of construction is very roughly estimated to be between 2 billion and 20 billion dollars, and yearly maintenance is estimated at 10 million to 100 million dollars. Amazingly, this seems to be a bargain compared to the cost of our current space endeavors. Oh, and Smith guesses that the sonic boom produced by a launch would be audible from a distance of over 100 km.
|Thursday, April 10th, 2008|
|Friday, January 18th, 2008|
|Converting HTML to text
I just spent a day figuring out how to force Python to convert html entities (escape sequences) into acceptable 8-bit characters while losing as little information as possible (e.g. I wanted 'ř' to appear as 'r' not 'ř', but I wanted 'ô' to appear as 'ô' since that is an acceptable 8-bit character). For some reason, this is not an easy thing to do. I eventually hacked out the following solution however.
"""Replace all html entities (escape sequences) in the string s with their
ISO Latin-1 (or bytecode) equivalent. If no such equivalent can be found
then the entity is decomposed into its normal form and the constituent
latin characters are retained. Failing that, the entity is deleted."""
i = s.find('&',i)
j = s.find(';',i)+1
identifier = s[i+1:j-1]
if not j==0:
replacement = ''
if identifier in htmlentitydefs.entitydefs:
identifier = htmlentitydefs.entitydefs[identifier]
replacement = identifier
identifier = identifier.strip('&;')
if (len(identifier)>1) and (identifier == '#'):
identifier = identifier[1:]
identifier = int('0'+identifier,16)
identifier = int(identifier)
replacement = chr(identifier)
replacement = unicodedata.normalize('NFKD',
s = s[:i] + replacement + s[j:]
i += len(replacement)
|Saturday, January 5th, 2008|
|Your Quotes for Today
"How much energy do we modern Christians put into condemning sexual sins compared to avoiding the judgmental, Pharisaical attitude of those with rocks in their hands? Who killed Jesus, adulterers or Pharisees?"
And two I don't know the origin of:
A person once asked Confucius, "What surprises you most about mankind?" Confucius answered, "They lose their health to make money and then lose their money to restore health. By thinking anxiously about the future, they forget the present, such that they live neither for the present nor the future and they live as if they will never die, and they die as if they never lived."
Life should not be a journey to the grave with the intention of arriving safely in a nice looking and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming, "WOW! WHAT A RIDE!"
|Sunday, December 30th, 2007|
|Transit, radiation, and Mars
Today I dug up some good news and bad news for prospective Martian tourists and colonists. Mainly I looked up radiation, but I've included some other fun facts below.
First, the good news. From what I can tell, solar flares do not seem to be as much of a problem for interplanetary travel as they have been portrayed. According to a NASA article, http://science.nasa.gov/headlines/y2005/07oct_afraid.htm
, solar radiation is adequately shielded by standard hull materials for spacecraft. Even a sizable flare should only result in moderate radiation sickness for the occupants of a spaceship with the 10 to 11 g/cm^2 of shielding used in current short-range craft, http://www.nasa.gov/mission_pages/stereo/news/stereo_astronauts.html
. In fact, it may be a good idea to plan trips during maxima of solar activity since increased solar particle radiation deflects galactic radiation, which is much more difficult to shield against.
Now for some bad news. A round-trip to Mars is estimated by Robert Brit at Space.com, http://www.space.com/scienceastronomy/mars_dangers_040120.html
, to entail (presumably for current spaceship hulls) something like 60 rem of radiation (1 sievert = 1 Sv = 100 rem). According to http://www.nasaexplores.com/show_912_student_st.php?id=04032381148
, the monthly, yearly, and lifetime radiation dosages for astronauts considered acceptable by NASA are 25 rem, 50 rem, and 100-400 rem (lifetime numbers depend on your age and sex). Moreover, he claims that each year on the surface of Mars you can expect to soak up on the order of 30 rem. Thus, if you decide to stick around (above ground), you can expect to exceed NASA's lifetime radiation allowance within about a decade.
In addition to abundant particle radiation, Mars sports an atmosphere consisting of 95% carbon dioxide with a pressure of less than 1 KPa (c.f. earth's sea-level pressure of 101 kPa and the 30 kPa pressure on top of the Himalayas), http://en.wikipedia.org/wiki/Mars_(planet)
. Finally, while Mars receives only 44% percent as much light as the earth, its thin atmosphere ensures an amount of UVB electromagnetic radiation exceeding that of earth, http://mpfwww.jpl.nasa.gov/mgs/sci/fifthconf99/6128.pdf
Oh, and the temperature? It ranges from −140 °C during the polar winters to highs of up to 20 °C.
|Tuesday, December 18th, 2007|
|Monday, December 3rd, 2007|
Today I saw a man dance in his motorized wheelchair. He was an older man with some sort of palsy that mostly paralyzed his right side. His wife sat in his lap and, among a host of other dancers, they circled, twirling slowly to a lovely waltz. It touched me very deeply, and I was compelled to comment, “Life is very beautiful. And sad.”
I saw this at the birthday party of a 79 year old woman whom I met at swing dance. I've danced with her on perhaps three occasions. On the last she invited me to her birthday party.
I'd estimate there were 200-300 people there. The event included five-plus kinds of dancing. When I showed up they were starting what is called, I believe, a dance of universal peace. There were three concentric circles, and the dance consisted of simple footwork performed, with accompaniment and direction, to a kind of group hymn. In the beginning of each round of singing you looked in to the eyes of the person on your right (for me) and, with emotive gestures (and frequently faces), sang the first four lines of the verse below.
Through your eyes shines the light
wonder of god in you
wonder of god in you
maaaa shaaa la mashalla
maa sha la mashalla
maaaa shaaa la mashalla
wonder of god in you-u-u
wonder of god in you
That done, you clasped hands with that person and sang while the two of you danced a half circle. Each verse was completed with everyone holding hands, and the cycle began again with your new neighbor. Periodically this was punctuated with individual steps.
It was all very harmonic, and I found it surprisingly enjoyable.