Thursday, September 29, 2016

Time travel

James Gleick's article in Nautilus about time travel is a good overview of what people have been thinking and hoping about the subject, but he omits Larry Niven's demonstration that past-altering time travel will not happen. (Note that Niven did not argue "is impossible.")

For those not familiar with the argument: If time travel can change the past, then the present also changes. This can happen again and again (see Dinosaur Beach for an excellent story on the subject), until some random grandfather biting the dust prematurely means the time travel method is no longer discovered. A "no time travel" state is the only stable history, and will therefore become the only one that exists.

And he concluded with a flourish—the kind of thing Hawking could get away with in the Physical Review. He had more than a theory. He had "evidence": "There is also strong experimental evidence in favor of the conjecture from the fact that we have not been invaded by hordes of tourists from the future."

Of course you might ask whether UFO's were visiting from the future instead of Proxima Centauri.

FWIW, there are some features of quantum mechanics that seem to allow states that are a little ambiguous about time. But even if that's what they turn out to be, at human scales you wouldn't notice. h is small.

Friday, September 23, 2016

Cotton Kingdom

AVI referenced a First Things article about Frederick Law Olmstead, which mentioned some of his books. He was described as an excellent observer, so I looked up Volume 1 of Cotton Kingdom (Volume 2 is hard to find by itself).

FYI, I found it inconvenient to use the laptop to read it, so I downloaded the EPUB version to read on a portable system. It was handier to carry around, but the OCR was terrible: Red River frequently turned into Eed Eiver or Eed Kiver, and footnotes got mingled with the regular text. I wish the OCR programs would put in a symbol for end-of-page--that would help get the lower bound on a footnote, at any rate.

He started in Virginia, and found startlingly poor people and transportation. He considered slavery evil, but testified accurately about what he saw and heard--when it supported his opinions and when it didn't seem to.

Some things happen "off-stage:" he didn't see much whipping, though people talked about it. The poor whites were almost always not just poor but feckless. Most slaveowners weren't rich, and not all approved of slavery. On many farms slaves got financial incentives to perform. Conversations are jarring. Travel was fraught with difficulties: one trip by riverboat didn't leave on time, or the next day, or the next day, or the next day...

Read it.

Scrolls again

The Herculaneum scrolls I wrote about may be even closer to being read. The Ein Gedi Scroll turned out to be Leviticus, which we already have. The Herculaneum scrolls may be the writings of the house philosopher (and probably only of very specialized academic interest), but I'll be interested to find out.


Madison is in the middle of an ancient glacial lake, and good solid stone can be quite a ways down. Sand. Builders drive deep pilings when they're building more than a few stories high.

Our home is on the edge of a (I suspect somewhat graded and shaped) ridge, and part of the foundation for the garage wants to move in a different direction than the rest of the place. Not badly--maybe in a decade or so we'll mudjack. Or maybe not.

That leads inexorably to the question: when you're building wide buildings on land that stands a chance of shifting in slightly different directions sometime in the next century, how do you plan the foundation to allow for movement? Cast one giant thick slab and trust it doesn't crack? Or put a buffer layer between the foundation and the construction?

Wednesday, September 21, 2016


We took the kids to Old World Wisconsin from time to time. It turns out that it is possible to fit a family in a room not much bigger than one of the kid's bedrooms.

I remember a little about some of the places we lived in before moving to Africa, and I remember visiting some relative's houses now and then. As a general rule, they weren't very big. But now: "Likewise, the median-size home has increased in size by almost 1,000 square feet, from 1,525 square feet in 1973 to 2,506 last year." (Our duplex seems to be less than 800 square feet--military housing from the 60's. We succeeded in making the basement legally habitable, though, so maybe our house is growing too.)

It makes housing a little pricey.

This story is strongly black-and-white--probably the regulators have something to say on their behalf--but it makes fascinating reading. Plausible-sounding rules have far-reaching consequences, and some groups seem hostile to the entire idea of small housing.

Revised micro-housing legislation proposes more expansive changes, including prohibiting congregate housing development in places zoned for neighborhood commercial centers and for low-rise multi-family buildings, such as small apartment buildings and duplexes. Such zones are exactly the parts of the city where most micro-housing was previously built and where it makes economic sense.

The linked article is about micro-housing--apartments, basically. When we moved to Illinois, we couldn't afford a 3-bedroom apartment, and were lucky that the third child wasn't yet born, because rules prohibited renting a 2-bedroom to 5 people.

Zoning rules push for more space between a new house and the street (old houses were grandfathered in), wider sidewalks, wider driveways--more land and more expensive. (The lots our duplexes were built on are now almost too small to lawfully build a house on!) Which presumably helps make apartments more expensive too, though there are some fixed expenses to recoup. In the middle, and especially the lower middle, housing eats up a huge chunk of the income, and leaves a lot of us "one paycheck away from disaster." (Ill health has driven several people out of homes in this neighborhood.) Or a fire, or a tree landing on the roof, or something else that has you paying for both the original house and for a place to live...

At the low income end once you drop below trailer court prices there doesn't seem to be anything left except public assistance.

True, some people don't do themselves any favors (the feckless, the slovenly, and the jerks), but there should be some sink-or-swim ways for them to fend for themselves. There's no place to build-your-own in the city (maybe in Detroit). There are tiny houses. (I'm not sure wood is a good choice for building rental tiny-houses--too easily damaged.) Policing is an issue in collections of small housing--the predatory have to be driven out, and if they're homeless as a result that's sad, but not unendurably so. (Those with serious mental illness are another matter--if it is severe enough there's not much we can do short of locking them in, and for others we can think of halfway homes.)

There's a lady who lives on a corner of the Capitol Square. Over the years she has accumulated a fair pile of blankets and whatnot. She's peaceful and clean and seems to get out of the way without hassle when there's an event on the Square, so I guess people just let her stay. On campus, groundsmen accidentally found a tunnel where someone had been living for at least a couple of years. They never showed up again, so nobody knows if this was a squatter or a student trying to save on housing costs.

This year's "Go Big Read" at UW Madison is Evicted. I gather it focuses on the landlords, if the NYT review is any guide. There may be other players involved.

Friday, September 16, 2016

Fluent in Math

How I Rewired My Brain to Become Fluent in Math

Anybody want to try to replicate the experiment?

I suppose by symmetry I should be willing to try to become fluent in Arabic (I just didn't have time to spare) or figuring out which colors go with which.


In the article circulating the past few days, Carlo Cipolla suffers from a slight poverty of language. Part of what he writes about is not stupidity but evil. His evil "bandits" are just one category of evil--other-destructive. Another is self-destructive. Or both. Dante had quite a list.

Thursday, September 15, 2016

Touch and autism

Lots of folks on the autism spectrum are uncomfortable with touching (bundling tightly is a different kind of sensation), and a Flemish group had a look at one aspect of touching: namely the difference between what you expect to touch when you grasp someone and what extra sensations you feel. They used hands and touched different fingers. (If I poke something with my index finger, I don't expect sensation on my pinky, and interpret that as whoever-it-is touching back.)

OK, interesting idea. They see a difference in reaction. It's a small study, and I wasn't overwhelmed with the differences, but maybe they're onto a connection there.

Comet busting

Have a look at a comet breaking up. Or at any rate having chunks come off. Hubble got some good pictures. The breakup is slow, and some of the smaller chunks seem to break up to invisibility themselves.

Gaudium et spes

Gaudium et spes (joy and hope) is one of those Vatican-II documents you hear referenced now and again, and I figured I should see what the scoop was.

It is wordy. Very wordy. In some ways that's inevitable, because they were trying to draft something that could be applicable in some way from slums in South America to the super-wealthy of Washington DC. Each section is more or less stand-alone. It would have been much more readable if they'd taken examples and illustrated their religious and social points from the examples.

Some of the things may have been surprises to people ("If one is in extreme necessity, he has the right to procure for himself what he needs out of the riches of others."), but I'd heard of them before. I gather that the emphasis on self-determination was relatively new.

One section was rather startling. It emphasized that men are broken and sinful, and that men's governments are oppressive and greedy and violent, and then went on to assume that international organizations would give pure and righteous correction to us all.

Maybe my lack of surprise for the rest was because I wasn't immersed in pre-Vatican-II attitudes.

UPDATE: Yes, I know they were probably thinking of themselves in the role of "international organization", or of people like or inspired by themselves.

Wednesday, September 14, 2016

Separating images

This looks interesting: using a kind of dual measurement to try to distinguish two very close sources. Rayleigh showed that two point sources couldn't be distinguished if their angular separation were less than a factor times the wavelength divided by the lens diameter. But their research suggests that if you are not doing direct imaging, it may be possible to do much better. Unfortunately I don't understand their paper well enough to say how practical this is likely to be, but I'll keep an eye on it. Maybe we'll be able to--well, "get a look" is direct imaging. How about "detect" binary star systems? OK, we detect them with doppler shifts and with occlusion effects if we're lucky. You know what I mean.

New particle?

Researchers using older LHC results from Atlas and CMS claim there is room for a new heavy boson that couple to dark matter. So said reports last week. The arXiv article is from last year, and garnered little attention until the authors made statements at ICHEP last week. Um.

As others (e.g. Motls and Dorigo have noted, there was room for a lot of low-significance guesses in the early data. Most of those bumps have gone away with more data. And though the article says the team showed their recent work at ICHEP, the linked papers had nothing to do with their arXiv article from last year--just stuff about what you could do with a new collider. (Since they don't have direct access to the latest LHC data, it's not terribly surprising that they don't have anything new to say yet.) It sounds like they are just touting a little "bump-hunting" from last year that nobody paid much attention to at the time.

I skimmed the paper, and didn't see much that jumped out at me--and I don't think I'll be going back to slog through it.

They're quite correct that there's a big problem with dark matter and normal matter--the latest results are squeezing the most popular models (WIMPs) out of the picture. Me? I suspect that dark matter interacts with neutrinos. That leaves room for them to interact with normal matter in the early universe when temperatures were high, and means that it will be next to impossible to detect their interactions now. Which isn't very encouraging to grad students looking for a thesis, or hoping for a Nobel for discovery.

Saturday, September 10, 2016

I'm shocked, shocked!

Apparently policemen have a macabre sense of humor. A dry-erase board soliciting suggestions for dealing with problems caused by the homeless who congregate at the end of State Street wound up including "Burmese tiger trap," "swarms of bees," and similar ideas. The administration is apologizing, of course, and some outsiders said this doesn't reflect the attitude officers on the street show in real life. Well, no, of course it doesn't.

I'm told med students and ER workers have a wacky sense of humor too. I'd bet that most folks working in life-or-death occupations blow off steam with jokes that would freak out peaceful desk jockeys. I work in IT these days, and even on the worst days(*), as one of our guys says, "Babies ain't dyin'." But at lunch some of our jokes might make the system users shiver. We have a team of people who like to help, but when the same (otherwise brilliant) fellow keeps coming back with the same problem, he can expect there to be a little behind-the-scenes merriment. But we'll cheerfully keep fixing the problem.

Prediction: Among themselves park rangers will have wry jokes about bears and over-confident hikers, ambulance drivers will have coarse phrases for frequently visited locations, and firemen will have theirs about places and stupid people tricks.

(*)E.g. When we lost an un-backed-up 3PB filesystem. We were saying to each other "Well, they needed more disk space, and now look--3PB of free space!" We got the system fixed, and only lost about 100,000 files, almost all of which were reconstruct-able--not too shabby.

Friday, September 09, 2016

Thief of time

Scanning the news stories about student demands at college, and the latest limit in the search for dark matter, reminded me of a fun book. "Contrary to the headmistress's instructions, Miss Susan did not let the children do what they liked. She let them do what she liked. It turned out to be a lot more interesting for everyone."
For something to exist, it has to be observed.
For something to exist, it has to have a position in time and space.
And this explains why nine-tenths of the mass of the universe is unaccounted for.
Nine-tenths of the universe is the knowledge of the position and direction of everything in the other tenth. Every atom has its biography, every star its file, every chemical exchange its equivalent of the inspector with a clipboard. It is unaccounted for because it is doing the accounting for the rest of it, and you cannot see the back of your own head.
Nine-tenths of the universe, in fact, is paperwork

You have to be careful with your training sample

If you don't choose wisely, your Artificial Intelligence beauty contest judge will wind up famous for the wrong reasons.
"The idea that you could come up with a culturally neutral, racially neutral conception of beauty is simply mind-boggling."

The case is a reminder that "humans are really doing the thinking, even when it’s couched as algorithms and we think it’s neutral and scientific," he said.

In counting aspects of beauty, do you weight a symmetrical aquiline nose more heavily than steatopygy? There's a good chance some other culture disagrees.

The article goes on to complain about algorithm-based law enforcement tactics, but that's a bit different--most people fear violent crime more than white-collar theft, and the unhappiness arises from the fact that the loci of violent crimes tend to cluster, and so do the side effects from policing.

But an algorithm for most beautiful? I remember one day waiting for a ride at Union South, and looking at the people around. One young lady seemed more attractive than the rest, and for want of more noble things to think about I tried to figure out why. I finally realized that she resembled my wife.

Thursday, September 08, 2016

Cell phone gun

You all probably heard about the gun that folds up to look like a cell phone. I saw reactions from "cool, I should get one" to "what evil-minded people those gun weirdos are." One thing I did not see was a use case.

  • Home Defense? Why bother with a fold-up?
  • Concealed carry to prevent a mugging? By the time you unfold the thing, the mugger will have shot you three times and be halfway down the block with anything valuable.
  • Parthian shot at a mugger? Do you think a mugger is going to leave you your "cell phones"? Anyway, judges frown on shooting people running away from you.
  • Assassination? You're going to get this past metal detectors, and then unfold it undetected, and then get close enough so you can hit the broadside of a barn. Yep, sure. A derringer would be smaller; or use a ceramic knife if you expect metal detectors.
  • Because it's a cool novelty? OK, impressing people is a valid use case. Still.

It finally struck me: You conceal it from your boss in a "No firearms" establishment where you have reason to expect random shooters. Chances are you won't be targeted first, so you have time to duck and unfold and fire.

I made notes but never actually posted about this one.


Malaria Capers is a very interesting history of the disease and its attempted cures, and its use (to cure syphilis). There've been many attempts at a vaccine, and plenty of treatments. BBC reports on a new attempt that shows promise in animals, attacking the parasite in a couple of stages of its development and, the article says, suppressing it for about a month. Pretty good--chloroquine we had to take every week. Over the years so many drugs have shown promise and failed, or begun to fail as the organism adapted, that it is hard to get excited. But who knows? Maybe this will be able to replace artemisinin, or maybe even be a long-term cure.

Monday, September 05, 2016

Race around the Pole

I've never been to the South Pole, but I work with others who have--and some even wintered-over. When IceCube was drilling its 2.5km deep holes in the ice, we had a lot of people in the drilling crew. They stood 8 hours shifts--the system kept running 24/7 (OK, there were a lot more than 24 hours in the day). If you work for 8 and sleep for 7 or 8 hours--what do you do with the rest of the time? Remember that these are clever, adventurous (or they'd not have taken a job at the Pole), creative, and very good at making and fixing things--and repurposing things.

Once upon a time, the Race Around The Pole was a bigger deal than it is now--a recreation for people sitting in the middle of nowhere.(*) It is still an important event--people devise some costumes and run/walk/whatever on this year's track around the South Pole. But a few years ago things had gotten a little competitive.

How about a dragon racing around? And yes, that's a hot tub in the back. I presume the ladies represent captive princesses. Hot water is gold there, btw.

Or perhaps a chariot?

It looks to me like the chariot wheels were made from the leftover spools that held the cable we shipped down.

Unfortunately, although we all cheer for the creativity, funding agencies tend not to have a sense of humor, and I gather word came down to scale it back. Since the drilling's done we don't have as many engineers down there anymore, so it's probably moot. But it would be cool to spend time working alongside a group like that.

I got the images from, but I couldn't link them directly--see them for more.

(*) I'm tolerably sure the airlines try to time various in-flight activities to keep the passengers from going stir-crazy. Food, ads, movies, whatever -- to break up the noisy monotony of an 8-hour flight.

Thursday, September 01, 2016

Squirrel tastes

This morning while we were getting breakfast together I noticed a squirrel out by the bird feeders eating a mushroom. I'd not realized they did that. Apparently they do. He was picky, though--the relic looked a little ratty and notched when I photographed it later. (Lots of glare, but you can learn something from the fact that the original mushroom was round.)