Wednesday, May 24, 2017

Medicine Wheel

I was tasked with finding things to do/see in Big Horn in the summer(*), and one of the first places that popped up (as opposed to generic activities) was the Medicine Wheel. Archaeology has always been an interest of mine, so...

Stanford has a web page. There one learns that:

n 1974, an archaeoastronomer named Jack Eddy visited this Medicine Wheel and studied its alignments, that is, its arrangements of rocks, cairns, and spokes. He found the arrangements point to the rising and setting places of the Sun at summer solstice, as well as the rising places of Aldebaran in Taurus, Rigel in Orion, and Sirius in Canis Major -- all bright, important stars associated with the Solstice. Later another astronomer, Jack Robinson, found a cairn pair that marked the bright star Fomalhaut's rising point with the Sun 28 days before solstice.

and

The dawn or heliacal rising of a star is important because it pinpoints a date exactly. This is the day a star is first seen, just before dawn, after it has been behind the Sun for an entire season. From about 1200 AD to 1700 AD, these 4 stars would have acted as solstice markers for the Native Americans - Fomalhaut (F to D) would rise 28 days before the Summer Solstice, Aldebaran (F to A) would rise during the 2 days just before the solstice, Rigel (F to B) would rise 28 days after the solstice, and Sirius (F to C) 28 days after that, at the end of August and hence marking the end of summer and time to leave the mountain.

Which sounds quite complicated and interesting, but the diagram associated with it is not so promising

The cairns aren't exactly neat geometric points, and the resolution doesn't look much better than 5 degrees. And the cairn orientations don't seem to line up with their putative use as observation points. If Jack started with a list of stars significant to the Cheyenne and found things that lined up with each of them, I'd be OK with describing it as a rough-and-ready calendar--though not 100% convinced. If he got a list of stars that were "pointed at" and then went looking for which were significant, I'd be less convinced. "look elsewhere effect"


(*) Things that don't involve strenuous hikes, and preferably also no precipices.

Wednesday, May 17, 2017

Whole hog

That phrase. "I do not think it means what you think it means."

Tuesday, May 16, 2017

Memorable but unremembered

On I65 one of the side roads leads to Walesboro. That name always reminds me of the line in "A man for all seasons": "Why Richard, it profits a man nothing to give his soul for the whole world... but for Wales?" Except, of course, that I generally only remember the last 3 words, and have to reconstruct the rest. It's a memorable line, but I can't remember it. I'm even worse at getting all the bits in order for the unforgettable passage that ends "Yes, I'd give the Devil benefit of law, for my own safety's sake!"

I've an excuse when an earworm of Hava Nagila turns into mud (or into Halva Nagila, or into Harvey and Sheila, or just repeats like a scratched record), since I never learned the actual words and my ear isn't tuned to pick out the phonemes of Hebrew.

But English is my native language. When my mind says "This is important; stuff it in one of the quick-access slots," how come half of it falls on the floor? I summon up a teaser or key line or executive summary, but most of the details are missing.

Credentialling

On I74 headed east to Indianapolis, there is a billboard touting the services of a law firm that promises to help you after an injury or similar loss. What caught my eye as I drove by was that they describe themselves as "an award-winning law firm."

Not "a case-winning law firm?" Or does that not matter until validated by some awards committee?

Wednesday, May 10, 2017

Two timing

Back in high school I read a book by Eddington in which he was explaining space-time. In one section, he suggested that different universes, with different numbers of space and time dimensions, would be limited in the ways they could intersect: that you could have a portal from a universe with 3 space and 1 time to one with 3 time and 1 space, but not to one with 2 time and 2 space dimensions. To this day I have no idea why he thought that.

However, it left this science fiction fan with a nagging idea for a setting: suppose we had 2 time dimensions? What sorts of things could happen?

Solving that puzzle had to wait until I got around to working out some of the dynamics, and when I finally did it turned out some other folks had already been playing with the idea. Including Sharshakavili (sp) and somebody named Bars.

To solve the dynamics you first have to decide whether you can violate causality on a macroscopic level--can somehow make your grandfather decide to become a monk before he met your grandmother? (Never mind quantum non-causality; I don't think I want to go there right now.)

I said no, and used a framework like the one Einstein used but with two time coordinates. Then you run into the question--how do you interact with a photon that's running along a slightly different timeline?

Hmm. I guessed that you would still be able to see it--but there'd be some probability that you'd miss seeing it entirely.

That was even cooler--you automatically would have trouble seeing some of the matter in the universe--it would be dark to you.

Presumably near things are mostly on the same timeline, and you'd only start to get major differences far away. OK, so what would a photon look like that came from a distant galaxy with a different timeline?

Oops. It would have the same number of "vibrations" in what would look like a shorter time--meaning it would be blue-shifted. Distant galaxies are red-shifted due to the expansion of the universe, and apparently the expansion is increasing (unless the supernova distribution is wrong somehow), which would make the redshift stronger, not bluer.

Plus, the blue shift complicates energy conservation. I think there might be a way to finesse that, but without either blue-shifted light or disappearing photons I think it safe to say we don't have macroscopic extra time dimensions. I gave up on the study. (If somebody wants to play around with a sci-fi setting in which multiple timelines interleave, feel free.)

On the other hand, if you've got 10 dimensions curled up in M-theory, Dr. Bars suggests that you can spare one for an extra time dimensions. He uses a formalism that uses position and momentum in symmetric ways, and argues from that symmetry that there should be another time dimension. (I think.) Unfortunately I don't share his optimizm about CERN discovering supersymmetry anytime soon--or anytime at all, for that matter.

Sunday, May 07, 2017

Doing good

From Sidelights:
What embitters the world is not excess of criticism, but absence of self-criticism. It is comparatively of little consequence that you occasionally break out and abuse other people, so long as you do not absolve yourself. The former is a natural collapse of human weakness; the latter is a blasphemous assumption of divine power. And in the modern world, where everybody is quarrelling about the urgent necessity of peace, nobody notices how this notion has really poisoned the relations of nations and men.

Thus the Irishman would never have minded the English saying he was mad; or even that he was murderous and slanderous and cruel. There was something to be said for the assertion; and Irishmen were often ready, if not to admit it about themselves, at least to admit it about each other. The trouble began when the Englishman advanced the obviously ludicrous proposition that he himself was sane; that he was practical and sensible and well-balanced. No wonder a whole nation went wild at so fantastic a fancy as that.

What the Prussian said about the French or the other Latins was simply ignorance: the ignorance found only among the seriously educated. It was what the Prussian said about the Prussian, that made half the world smell afar off something that stank with spiritual pride.

The moral is the same about much milder and more amiable things; indeed it is rather specially true about mild and amiable things. The trouble with the philanthropist is not that he does not love all men moderately, but rather that he generally loves one man too well. And, contemplating the sort of philanthropist who is also an egoist, I am tempted to recommend him to try being a man-hater, that men may more easily love him. I am tempted to say to him: Hate men as a sort of holiday; beat and kick them for a reasonable interval; burn down their houses, in moderation, and lay waste all civilization within reasonable limits: But do not be kind merely to exhibit your own kindness; for that is an insult that is never forgiven.

When you are helping people, pray for a spirit of humility; I had almost said, when you are helping them, pray for an appearance of helplessness. The deadly word ‘patronage’ is, like so many such, a word that has decayed from a much nobler meaning. But in this sense we may find another significance in the old conception of patron saints. It may mean that a man has jolly well got to be a saint, before he ventures to be a patron.

Chesterton nodded a bit here: he did not predict the rise of pat-your-self-on-the-back-for-being-so-observant self-criticism.

Friday, May 05, 2017

Good ideas

One of the talks concentrated on how we should try to organize analyses, and not keep re-inventing the wheel. She showed lists of related analyses, and urged us to make sure that all code was in the repository and not private sandboxes. And that students should learn how to have their code reviewed.

All noble goals. (She has led a working group, is one of the young big names in the experiment, and is a pleasure to work with.)

However, several people who've trained more students than she pointed out a few problems. Part of the apprenticeship is to do some of the exercises yourself, and there's no better way to learn how to minimize a log likelihood function on a complicated data set than to do it yourself. And, then, when you want to try a full-blown analysis, you'll tend to use what you developed and understand the best.

Another problem is validation--are you sure you don't have some subtle bugs in your code or your procedures? They do a lot of cross-checking, but often there's no substitute for an independent analysis. Sam Ting tries to make sure that two independent analysis groups don't communicate with each other. He allegedly is the only one that sees both.

On the other hand, my analyses over the years would have been improved by some better coding practices and review. I kept a record of all my coding errors over a year, and found that the plurality were cut-and-paste errors. She's quite right about that.

And private code from somebody's sandbox is hard to maintain, or re-use when the student has graduated and somebody else wants to process a couple more years' data.

Reconnection

One of the talks was on the possibility of seeing solar flares with the IceCube neutrino detector. That might seem a little counter-intuitive: how do big magnetic disturbances manage to make neutrinos?

A plasma with a magnetic field in it will carry that magnetic field around with it as it moves. (The magnetic field acts on the plasma and the plasma acts on the magnetic field--plasma physics is hard.) So far so good--the plasma erupts from the Sun, and carries some of the Sun's magnetic field with it. Think of it stretching those field lines further out into space.

But it turns out there's a lot of turbulence there too, so the plasma sometimes gets whirled around on itself. What happens when the magnetic field lines cross?

You get what you might think of as a magnetic short circuit. The magnetic field "lines" join and shift--quite rapidly. And this happens over a fairly sizeable chunk of space.

A rapidly changing magnetic field produces an electric field (and vice versa, of course). So out in the middle of Nowhereville-By-The-Sun, a bit of the flying plasma experiences a strong electric field. The protons move one way, the electrons another. Most of them bounce off other things and slow down and go back to balancing each other's charge eventually, but some luck out and keep getting accelerated (remember that the reconnection region can be large). Acceleration over a long distance builds up speed.

Some of those protons (electrons tend to get scattered away more easily) head out in our direction, and eventually may hit the Earth's magnetic field and spiral in to be part of an aurora.

The protons of interest here head back to the Sun, where some of them smash into another nucleus. Those kinds of smashes usually produce pions, and the charged pions eventually decay into a muon and a few neutrinos. And we can maybe see some of those neutrinos. They aren't terribly high energy, but they're higher energy than those usually produced in the Sun--maybe 10 times higher.

It's ironic--neutrinos produced in the center of the Sun are ordinary low-ish energy, but those produced on the outside during flares can be quite a bit peppier. I can't think of any everyday examples, but I notice that boiling water in a pot only really splashes you when bubbles reach the surface and pop. The pop can really fling hot water around. Remember boiling something dry too fast back in chemistry class, and getting "bumping?"

We expect similar sorts of things to happen, but on even larger scales, when the blast wave from a supernova crashes into interstellar gas. Some of the neutrinos IceCube detected were over 10,000,000 times more energetic than ordinary solar neutrinos.

Thursday, May 04, 2017

Limits

It isn't a great secret, though the latest negatives haven't been officially published. I suspect we won't have a smoking gun unless/until a Gamma Ray Burster or supernova lets loose in our galaxy. IceCube is designed to detect higher energy neutrinos than a supernova is likely to produce in its explosion, though the resulting shock wave hitting matter nearby is another matter.

Yes, I know it's odd, but the reactions that produce the supernova explosion are supposed to be the ordinary nuclear ones. When the shock wave from the blast (with magnetic field embedded) later interacts with gas (expelled from the star years before), the resulting interactions can accelerate particles to extremely high energies.

What that means, if I understand the matter correctly, is that the most likely neutrinos are too weak to ring up unless there are boat-loads of them, and we'll only get boat-loads if the source is close. And we might have to wait a while for the really high energy stuff to show up, since it isn't produced right away. And even longer for the protons and other nuclei to arrive. (If a source 50,000 light-years away produces iron nuclei whose trajectory is bent a mere three degrees, they'll arrive over three months after the light and neutrinos do. And we don't know in any detail what the magnetic field are out there, so we can't predict when.)

So we see GRBs in other detectors (SWIFT), but don't see anything out of the ordinary in IceCube. So far. Maybe there's an unnoticed glitch in the analyses: I'm not in a position to tell. I just sit through the talks, which show large p-values after unblinding.

There are plenty of things we can do, but some of the tantalizing problems are staying that way.

Tuesday, May 02, 2017

Elders

You presumably pick elders as leaders because experience has given those of them willing to learn some perspective, an understanding of what patience means, some sense of proportion, and accumulated knowledge. Not that we have a habit of doing that in this country, but think about organizations of smaller scale than the state, and you may see instances of what I mean.

You'd also hope that habits of virtue would provide some inertia against the pulls of temptations.

Maybe they do--somewhat. But I suppose that power has its own set of temptations that most of us haven't been exposed to: to listen to sycophants, to be flattered by groupies, to come to enjoy arbitrary exercise of power. But history and literature (and, sometimes, our acquaintances) are full of the theme of a worker/conqueror who builds a fortune/dominates an empire only to have the children/grandchildren (born to power) fritter it all away. (Yes, I know I'm defining virtue a bit widely when talking about warlords, but they have to have at least some self-discipline and courage.)

I'm not sure there's a simple and robust way to survey this. If, for example, you looked at the history of family businesses, you might have some difficulty, from outside the family, in distinguishing mere lack of skill from carelessness.