Monday, May 31, 2010

Neutrino mixing

From a CERN press release today:

Geneva, 31 May 2010. Researchers on the OPERA experiment at the INFN[1]'s Gran Sasso laboratory in Italy today announced the first direct observation of a tau particle in a muon neutrino beam sent through the Earth from CERN[2], 730km away. This is a significant result, providing the final missing piece of a puzzle that has been challenging science since the 1960s, and giving tantalizing hints of new physics to come.

The neutrino puzzle began with a pioneering and ultimately Nobel Prize winning experiment conducted by US scientist Ray Davies beginning in the 1960s. He observed far fewer neutrinos arriving at the Earth from the Sun than solar models predicted: either solar models were wrong, or something was happening to the neutrinos on their way. A possible solution to the puzzle was provided in 1969 by the theorists Bruno Pontecorvo and Vladimir Gribov, who first suggested that chameleon-like oscillatory changes between different types of neutrinos could be responsible for the apparent neutrino deficit.

Several experiments since have observed the disappearance of muon-neutrinos, confirming the oscillation hypothesis, but until now no observations of the appearance of a tau-neutrino in a pure muon-neutrino beam have been observed: this is the first time that the neutrino chameleon has been caught in the act of changing from muon-type to tau-type.

Antonio Ereditato, Spokesperson of the OPERA collaboration described the development as: "an important result which rewards the entire OPERA collaboration for its years of commitment and which confirms that we have made sound experimental choices. We are confident that this first event will be followed by others that will fully demonstrate the appearance of neutrino oscillation".

"The OPERA experiment has reached its first goal: the detection of a tau neutrino obtained from the transformation of a muon neutrino, which occurred during the journey from Geneva to the Gran Sasso Laboratory," added Lucia Votano, Director Gran Sasso laboratories. "This important result comes after a decade of intense work performed by the Collaboration, with the support of the Laboratory, and it again confirms that LNGS is a leading laboratory in Astroparticle Physics".

This is good news, as it means they may be able in another year or so to collect enough data to measure the mixing between those two neutrino flavors.

You may wonder why one type of neutrino would change into another; and rightly so because this is certainly an odd sort of phenomenon.

First notice that, contrary to the accepted wisdom up until '69, neutrinos turn out to have a mass. If they had been truly massless particles, they would always move at the speed of light and never have the opportunity to turn into anything else.

Second: it isn't just neutrinos that can change type.

We find there are "families" of particles that have the same sort of arrangements. Within the "first generation" family you have the electron (charge=-1), electron neutrino (charge=0), up quark (charge=+2/3), and down quark (charge=-1/3); plus of course their antiparticles. The "second generation" family has the muon, muon neutrino, charm quark, and strange quark having the same relation; and the third has the tau, tau neutrino, top and bottom quarks respectively. These aren't the same particles, and nobody has succeeded in finding a structure to them that would make the electron a ground state, muon an excited state, and tau an even more excited state of some primal "preonic atom." People have tried (me too) and they seem to be fundamentally different.

So a meson made of a bottom quark and an anti-strange quark is different from one made of a strange quark and an anti-bottom quark, but it turns out that they can and do transform into each other at a measurable rate. The trick is that they can temporarily transform into an intermediate state, which can then transform into the other type. Notice that electric charge stays the same: 0=0. It also appears as though a particular type (flavor) of quark doesn't have a well-defined mass, and a quark with a well-defined mass doesn't have a clearly defined type. This "flavor mixing" is an area of active research, and you can easily imagine why.

Neutrinos can do the same kind of thing for apparently the same reason. The neutrino masses are small (though the tau neutrino mass isn't known well), and difference in masses between neutrino types are also very small, but the masses of their partner particles vary a lot. We don't have any neat way to make a beam of tau neutrinos, because tau's are so unstable and hard to work with. Beams of electron neutrinos from reactors (or the sun) are easy and intense and, unfortunately, of such low energy that you haven't a prayer of seeing one turn into a tau neutrino and generate a tau in a subsequent reaction. So you need beams of electron neutrinos from anti muon beams--which also give you anti muon neutrinos to contaminate the signal with. It takes some careful analysis to make sure you can tell one from the other, but muon neutrino and electron neutrino mixing has been seen.

You can pick up more details on how this is modeled, but it helps to know a little about matrices.

Saturday, May 29, 2010

Advice for the great

I cannot find the original, but I remember reading story this years ago. I will paraphrase.

It occurred one day to an avaricious and headstrong monarch that perhaps he should think about how posterity would see him, so he summoned a wise man of the kingdom and asked him: "What can I do to benefit the world?"

The wise man answered "The best single deed within your power is to sleep until noon, so that for that interval you will not afflict mankind."

Friday, May 28, 2010

Why Politics Is Unjust

Daniel Jackson at Sense of Events, a blog he shares with Donald Sensing, explains in two posts Bailey's Stratagems and Spoils and an example of how it plays out in the real world. Essentially, there are two kinds of rules: "normative rules" describing how things are supposed to be and "pragmatic rules" for how to win; honestly or not. (I'll have to read the book sometime.) To win requires knowing how to mix the two: playing to the house with the normative rules (make yourself sound good or victimized) and getting your licks in with something not quite ethical. He illustrates why having officers required to keep the peace tends to mean that the side that threatens more violence first tends to win: why having easily mobilized thugs is so useful in a peaceful society.

It isn't just limited to the ancient history of coal company goons: you can read about the same sort of tactics every other week in your local paper. Somebody "lacks advancement," and the threat of demonstrators looms.

Sunday, May 23, 2010

Good News on Ebola

Researchers have a start on a monkey vaccine. This is all preliminary, but so far it seems to offer some protection to macaques. They were immunized and then exposed to a new strain that wasn't part of the vaccine preparation.

The fly in the ointment is the problem of human testing. There can't be a control group for a disease with 60% kill rate, and I'm not sure how many volunteers there would be for a test group.

Saturday, May 22, 2010

Where the needs are

Germany has over 30 Autobahnkirche.
Wolfgang Fritz: "In my life I have to fight all day. In the construction business, we fight about everything. But I also have to fight to stay a human being."

One site is family-owned:

And at Exit 76 I find one of Germany's biggest motorway services. It is owned by Manuela Strohofer and her family.

"We have three gas stations, a garage, a hotel, a swimming pool, three restaurants - and our church, of course!" reveals Manuela.

The Strohofers decided to build their motorway church after Manuela's younger brother Anton was killed in a road accident.

"Our church has a motto," says Manuela. "It's from Matthew chapter 11; verse 28 where Jesus says 'Come to me, all of you. You're tired from carrying heavy loads and I will give you rest'."

R&R or R&W?

Tuesday, May 18, 2010


Eve Tushnet wrote how sin is like a child. She's an interesting and lively writer:

"I've done a lot of awful stuff in public, because I'm awesome like that, so if you know me just assume that this post is about something worse than the thing you're thinking of."

Monday, May 17, 2010

What do Zombies mean?

\I’m told that "Invasion of the Body Snatchers" drew on Cold War themes, in particular the fear of alien traitors among us who look just like friends. Or at any rate, this contributed to its popularity: it touched a nerve.

I’m not in close touch with pop culture, but it seems to me as though every few weeks there’s some new zombie-themed book or movie or game; and I frequently hear about "preparing for the zombie invasion."

We all know (I hope!) that zombies are fiction, but their popularity says something about what people are feeling. In this version zombies are living dead who reproduce by killing or infecting others. One zombie becomes many, and your only hope for survival is to physically isolate yourself, maybe with a few trusted allies, and kill everything outside that comes close, because they are probably zombies. All civilization disintegrates.

The coming of the zombies begins small, with only one or two, but avalanches into a complete breakdown of trust as those we thought were friends become poisoned and band together against us in mindless hatred. In some stories the zombie infection could have been contained at the start if the powers that be had acted wisely or decisively, but they never do.

I take it that zombies are a symbol of something many of us worry about. Not that we’re terrified, or we’d give over symbols and tell the stories straight out; but worried: something is happening, something is coming, and it is very bad. Perhaps the "end of civilization," just as in the stories, is what we see looming.

There seem to be a few parallels in modern society. I find less and less of a "we’re all in this together" feeling. Race relations are in some places better than ever with opportunities galore and a well-off black middle class; but with a third of blacks locked into a ghetto culture, and with demagogues hard at work, I can’t say that I find the black/white climate overall is very good. Hispanic/white and Hispanic/black relations are pretty uneven too.

But I don’t think race relations are the whole story, or even most of it. There’s a universality to the zombie invasion that doesn’t map onto "us vs them" racial splits. Even the intense political/philosophical divides don’t have that same universal threat. It doesn’t make artistic sense to equate them.

Despite the many electronic means of connecting with each other I see less interaction with neighbors than a few decades ago (I’m part of the problem myself here), and although we know more about people we don’t know them as well. By itself that’s hardly a thing to fear, but our inchoate sense of isolation magnifies other threats. Still, that doesn’t seem quite enough to justify the zombie myth.

But if we flip the order of events in the zombie story, the zombies start to make excellent sense. Suppose the economy collapses. Who can you trust? Nobody you don’t know (and in a city that is essentially everybody), and not even all of those you think you know. This isn’t an exaggeration: civilization can quickly break down: it did in Argentina.

Perhaps the zombie myth reflects the fear that we, already somewhat isolated, will be living in an "every man for himself" wilderness if the powers that be continue their feckless course.

Sunday, May 16, 2010

Bon Mots

Youngest Son noted that up-to-date New Age types try to find a Spirit GPS instead of an old-fashioned Spirit Guide

Friday, May 14, 2010

Book of Days by Gene Wolfe

This is a collection of short stories organized by holiday: Arbor Day has a story involving a tree, Lincoln's birthday is commemorated with a story called "How the Whip Came Back," and so on. The longest story is "Forlesen" (for Labor Day), a Kafka-esque piece about work in middle management with an acrid edge that suggests bitter experience with management fads. "St. Brandon" is a wonderful sendup of Irish folk tales.

You won't find many cheerful stories among them, but Wolfe is a skillful writer. I'd say "read it," but with the caveat that when I said that to my better half she found the stories she read depressing.

Double life

You should get to know the head of the Social Security Administration. Really. Go read it.

Friday, May 07, 2010

Morgan Hill

What in the world is going on in Morgan Hill High School? The administration claims they were trying to forestall possible violence, but if they were really that afraid of violence they should have cancelled Cinco de Mayo entirely (and if scuttlebutt is true, good riddance to a fake holiday).

I find no defensible reason for Mexican students at a US school to take umbrage at US students wearing US flags during an unofficial celebration of a foreign sort-of holiday. If they consider that to be "in your face" offensive, they’ve got a whole world of surprises waiting for them. I’ve seen substantially worse than that as an American visiting in Europe, and that’s a moderately friendly region.

Soldier of Arete by Gene Wolfe

Years ago I read The Shadow of the Torturer and the three subsequent volumes (I hear there are more now), patiently waiting for the appropriate volumes to be returned to the library so I could read them in sequence. I thought it a very good series, and never got around to acquiring the set myself. (An odd contradiction, I know) His name came up recently and I figured I should see what he’d written recently.

Soldier of Arete turns out to have been the middle volume in a series—and it turns out not to matter much. Latro is a warrior, of hero caliber, who often sees the gods—but who cannot remember anything but the current day, and must rely on his papyrus diary as his memory when he has time to read it. The era is shortly after the defeat of the Great King by the Greek alliance. Wolfe has fun with the Greek names: which group is "Thought" and which is "Rope" and so on. Latro is traveling with his loyal slave girl, a mantis, a soiled dryad (shouldn’t have done that, Latro—now Artemis is mad at you), and "the black man" on what initially seems a simple but difficult mission, but gets deeply complicated by his new directive from Artemis. Gods and ghosts and magic are central to the book, and I suspect the confusing ending is related to the missing first volume.

Were it not for the ending I’d confidently say "read it," but I think I need to find the first volume before I can properly judge it. Wolfe is imaginative, has done his homework on ancient Greece and Thrace, and has the chutzpah and skill to pull off a prose passage by Pindar.

May and scrapings

I called Youngest Daughter to look at a bedraggled wet baby rabbit on our sidewalk at the garden border. It was no larger than my fist, and didn’t move a muscle. We’d had a steady light rain all day, and the temperature didn’t get above 46F all day. I set off on my errands, figuring that as soon as we were gone the rabbit would high-tail it for the burrow. I’d forgotten that most of the rabbits in the area seem to favor scrapings instead—and scrapings offer no shelter from rain and cold. It was fallen on its side when I came back with Youngest Son, and is now buried in the new garden I’m digging where the tree used to be. May in Wisconsin…

Wednesday, May 05, 2010

Bon Mots

Youngest Son noted that in contrast to books, you can tell a pop singer by her covers.

Sometimes by her physical covers too... she may even bald herself or streak if she's gaga for attention.

Sunday, May 02, 2010

Worship Servants

The motto of a worship team needs to be "He must increase and I must decrease." The team stands before the congregation and plays and sings the songs they've practiced all week—and instead of looking for applause the way every other musician does they hope the congregation sings praises to the Lord and forgets about the team.

C.S. Lewis wrote in The Weight of Glory

It is a serious thing to live in a society of possible gods and goddesses to remember that the dullest and most uninteresting person you may talk to may one day be a creature which, if you saw it now, you would be strongly tempted to worship, or else a horror and corruption such as you now meet if at all only in a nightmare.

All day long we are in some degree helping each other to one or the other of these destinations. It is in light of these overwhelming possibilities it is with awe and the circumspection proper to them, that we should conduct all our dealings with one another, all friendships, all loves, all play, all politics. There are no ordinary people. You have never met a mere mortal, Nations, cultures, arts, civilizations, these are mortal, and their life is to ours as the life of a gnat. But it is immortals whom we joke with, work with, marry, snub, and exploit -- immortal horrors or ever lasting splendours.

When we look out at the congregation we see saints: priests appointed by God to sing praises and authorized to bring petitions and thanks before His throne. He hears them when they call. There is not an "ordinary" human in the group, and they have assembled to worship God in a special way together; with songs and prayer and blessing and recitation and instruction and a holy meal.

Our job is to shape the service and sing and pray and play our instruments to make it easier for the congregation to pray and sing their worship together. Applause is not a reward but a defeat.

Our brothers and sisters don't always have musical training, so we guide them in songs so they can sing their best. Some are shy to speak out in service or have trouble pronouncing long words—no matter, they are priests and we their servants in worship. Perhaps some have never thought before to pronounce God's blessing on their neighbor—we can model it for them.

That worshiper whose voice drifts between keys is an exemplar of humble service to poor children, and whose holiness I do not come close to emulating. Dare I interpose announcements about potlucks in between his praise to God and the reading of God's word?

No matter whether the culture has the congregants dancing the aisles or kneeling at the mourner's bench—our task is just to make it easier. They do not need us: God hears them just as well when they pray without a leader, or sing a capella without a director.

As for me—I enjoy being the center of attention and praise. So my current job is nearly ideal—the more perfectly I anticipate needs and adjust the monitors, the more invisible I am.

Saturday, May 01, 2010


I've said before that I've never seen a science report on a subject I was familiar with that didn't contain at least one misunderstanding--unless it was an entirely fluff piece like some of the recent LHC stories. I don't think I can describe this effects of this better than Michael Crichton. Go read his speech about speculations. The "Murray Gell-Mann Amnesia effect" is just a side note, but a good one.