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Popular topics on this page:
The Anthropic Principle
Lisp Machine "Space-Cadet Keyboard"
What I said on Facebook
Here comes Bayesian science
Panic and paranoia are not my hobby

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Panic and paranoia are not my hobby


Have you noticed how many people seem to have settled into a lifestyle of permanent panic, fueled by inflammatory news media and the Internet?

This article describes a case (although I think the article gives Fox too much credit; the poor gentleman was surely in touch with more extreme panic-mongers through the Web or other media). Chronic panic is common, and I refuse to be drawn into it. Some things to watch out for are:

  • Media that often report just one side of a controversy, especially lawsuits that haven't gone to trial.
  • The attitude that only a few news sources are to be believed — the rest are lying or concealing things.
  • A compulsion to "spread the word" on Facebook and other forums. Some people on Facebook say nothing of their own — they just copy-and-repost or share links. In my experience, information that travels through "pass it on" or "copy and repost" is false 99.9% of the time.
  • The feeling that every issue is a moral issue and that civilization will collapse if the wrong side wins.
  • Above all, the notion that everyone has a duty to pay attention to this issue right now or something terrible will happen.

The term "culture war" is often used. Well, yes, there is a constant struggle between good and evil in our culture. But not every little dispute is part of it. I am not one of those who feel that every little opinion of mine is the will of God, and every opinion contrary to it must be straight from the devil. Sometimes opinions are just opinions. When morality is perfectly clear, we can still differ about what will actually happen if a policy is adopted, or even whether the background facts have been gathered adequately.

Anyhow, when one has a moral conviction, often the right thing to do is hold it, firmly and quietly, rather than chattering constantly and trying to debate everyone, or (worse) shunning everyone who doesn't agree.

It is not my job to pay attention immediately to everything that anybody on Fox, CNN, or Facebook tells me to. I run my own mind — they don't. I won't let other people keep me in a state of panic and exhaustion with one artificial crisis after another. We weren't killed off by race riots in 1960, nuclear war in 1975, an environmental crisis in 1990, or the recession in 2008. Calamities commonly fail to happen as predicted.

I think part of what's going on is psychological — some people get undue enjoyment from making themselves and others panic. In fact, some people are attached to the emotion that comes from dire warnings that they don't even actually believe. Have you seen people circulating warnings on Facebook and not acting upon them themselves? It's common. It's unhealthy. Personally, I don't want my emotions to be out of sync with my knowledge and beliefs.

As for actually making the world a better place, you're not much help unless you understand an issue deeply, and that means not all issues are your job. Superficial panic about 1000 things that you don't really understand isn't going to do anybody any good. Stick with a few things that you do understand, and leave the rest to others.

And avoid an excessive diet of panicky media even if it means being less accessible to your friends.

(I thank Ron Wodaski for the link to the Salon article.)


Here comes Bayesian science

An important shift in scientific method has been taking place, in many different fields of study, over the past twenty years or more. It's based on Bayesian reasoning and Bayesian statistics, by which we mean an approach to statistics derived from a theorem that was formulated by Rev. Thomas Bayes (1701-1761).

One of the most obvious uses of Bayes' Theorem is in medical diagnosis, so that's where I'll start. Suppose you have a patient with a headache. Headaches can be caused by brain tumors. How likely is it that your patient has a brain tumor? It depends on:

  • How common headaches are;
  • How common brain tumors are; and
  • How often a brain tumor produces a headache.

The hypothesis H is that the patient has a brain tumor. The evidence E is the headache. We want to find the probability of H given E, which is written P(H|E). To find it, we need to know the three things I just mentioned, which are P(E) (probability of a headache), P(H) (probability of a brain tumor), and P(E|H) (probability of a headache given a brain tumor). The formula is:

(Sorry if I've confused you. Note that in my example, H stands for Hypothesis, not for Headache. The headache is E, the Evidence.)

So if headaches are really common, and brain tumors are rare, Bayes' Theorem tells us that a headache is not a very strong sign of a brain tumor.

In the past I wrote about classical statistics. Bayesian statistics is different. In classical statistics, an experiment stands alone, and you use it to test whether a hypothesis is true. In Bayesian statistics, you use successive experiments to adjust your estimate of the probability that the hypothesis is true. That is, you start with an estimate of P(H) (which could even be that P(H) is totally unknown, but need not be), and you use the evidence to adjust your estimate so that it fits the evidence better.

This requires mathematics that goes beyond Bayes' Theorem, of course, but is closely derived from it. Crucially, you normally start with a distribution of possible values of P(H), not just a single value, and you adjust this distribution to be more compatible with the evidence. If P(H) is totally unknown, the distribution is flat (all values are considered equally likely until the evidence tells you that they're not).

The estimate of P(H) or the estimated distribution of P(H) is called the prior.

That's enough mathematics. I'd like to focus on some practical and philosophical consequences of using Bayesian statistics.

First: Bayes' Theorem is not the least bit controversial. It definitely does what it says it does. It's easy to re-derive from simple probability theory. In fact, for a while, I had to do this every time I used the formula, which I had trouble memorizing.

Second: "Probability" in Bayesian reasoning means more than just relative frequency. We are not looking at experiments carried out over and over like coin flips. Bayesian probability is more like degree of belief — not just a subjective feeling, but something subject to mathematical consistency. Roughly, a probability of 1/4 means that you know you are in one of four different situations, none of which is more likely than the others, and you can't tell which one, but the hypothesis is only true in one of them. It's rather like saying the probability that a coin is lying face-up is 1/2 before you look at it.

Third: Unlike classical statistics, Bayesian statistics models the gradual growth of knowledge. In classical statistics, every experiment is considered perfect and stands in isolation, unless it is so identical to another experiment that they can be combined. Its purpose is to yield a yes-no answer. The answer cannot be any more informative than the hypothesis. Ask a stupid question, get a stupid answer. In Bayesian statistics, the answer can be more than yes or no; it can be something you genuinely didn't foresee.

In fact, Bayesian statistics doesn't work if you're closed-minded. If P(H) is exactly 0 or exactly 1, P(H|E) will be the same; the evidence has no effect on it. So if you actually want to know anything, you have to assume that P(H) is at least a smidgeon greater than 0 and at least a smidgeon less than 1. This is called Cromwell's rule ("I beseech you...think it possible that you may be mistaken," Oliver Cromwell, 1650).

(In detail: If P(H) = 0 then, obviously, the whole formula comes out zero. If P(H) = 1, then P(E|H) = P(E) and the whole formula comes out 1.)

Fourth: Bayesian statistics strikes a balance between extreme empiricism and postmodernism. The empiricist says the mind is a blank slate and we learn from evidence. The postmodernist says that the mind is so enslaved to its preconceptions that we can never learn anything objectively true. The Bayesian says the mind has preconceptions but evidence can force them to be altered to almost any extent.

The graphical rendition of Bayes' formula is from Wikipedia.


Untrustworthy calculator

I've heard scattered stories about bugs in calculator apps for smartphones and tablets, and the other day I actually encountered one.

I was using Calculator• for iPhone, an older app that I bought back in my iPod days. It's in the App Store but the vendor's web site appears to be down. I have the current version (5.1.1).

I punched in 1 divided by 2.97 and got what you see above, about 0.214. The correct answer is about 0.337.

I am somewhat at a loss as to exactly what programming error they made. (Maybe some mathematically inclined reader can figure it out!) But what if I hadn't noticed?

Calculators are normally very reliable for many reasons. Many of them are built around hardware that is designed for nothing else. But I keep hearing that calculator apps for portable devices — that is, calculators that consist of software — are substantially less reliable.

The App Store page for this calculator mentions previous bug fixes to correct other incorrect results. To which I say: If the software haphazardly outputs the wrong numbers under obscure conditions, it's badly designed. Why does the Apple community tolerate any calculators with any known errors? A calculator is simple. It should work.

I bought this calculator app back when one wasn't bundled with iOS. Now there is one, and I have switched to it. I also use Pcalc Lite, which is a free preview of a commercial scientific calculator app.

But should I trust any of them?


What I said on Facebook

In response to a correspondent who was offended by my open advocacy of Christianity on my personal Facebook page, I posted the following message, which is, I think, my most popular Facebook posting ever. I have made one small improvement to the wording before posting it here:

Everyone: You are reading my personal Facebook page. I am a Christian and am not afraid to say so, right here. I've been told today that I should either (1) stop talking about my Christian beliefs, or (2) accompany them with a disclaimer that I don't claim my beliefs are actually true and it doesn't matter what you really believe.

Well, (2) is illogical and (1) would be hypocrisy. Not wishing to be either illogical or a hypocrite, I'm not going to do either of those things.

When I make a statement, it is not an attack on people. If I say God exists, I am not making a personal attack on people who say God does not exist. I am simply saying God exists. It would work the same way if I were saying the earth is round, or the sky is cloudy, or the angles of a triangle always add up to 180 degrees.

Quite a few scientists more prominent than myself are outspoken Christians. Examples include Francis Collins (Human Genome Project), Owen Gingerich (Harvard astronomer), and D. E. Knuth (arguably the greatest living computer scientist). I do not think that being a scientist requires me to keep quiet about religion.

At the same time, I will strongly defend other people's right to express and discuss beliefs different from my own. That is how thinking people arrive at truth. Your freedom is my freedom, and vice versa. I am surprised when people tell me that I shouldn't exercise my own freedom of speech, or that it should be taken away.

Finally, though I value a diverse group of friends, I want to remind everybody that no one is required to read this page at all. If it bothers you, you are welcome to refrain from reading it.


The "couponing" racket

Can't live with 'em, can't live without 'em. I'm talking about grocery store coupons, with which Americans have been inundated since the start of the Great Recession. Sometimes the savings are quite substantial. The labor of organizing the coupons, however, has become substantial.

People tell me how much money they save by "couponing." I reply: "Couponing" is not productive economic activity. It is a game the merchants are making you play. It may be to your benefit to play it, but only because they artificially created it.

I would much rather just have competitive low prices, without coupons.




For the first time in my life I have experienced an earthquake as more than a vague rumble. A couple of times in the past, I have heard rumblings and found out later that they were earthquakes. This one, however, was obvious.

On the evening of February 14, I was sitting at the breakfast table, surfing the Internet with my laptop computer. The house suddenly shook in an east-west direction; in fact, the wave seemed to enter the house on the west and travel to the east (opposite its real direction of travel; this may have been an illusion). There was little or no noise audible inside the house, and the whole event lasted less than five seconds. The shaking was much slower than the usual "truck-rumbling" earthquake. It was like one or two cycles of a sine wave at maybe 2 Hz.

I immediately looked up at the clock, which read 10:24 p.m. but turned out to be about one minute fast. At first I thought it had been an unusual wind gust, but it did not persist (and in fact the weather station is reporting little wind at present). I thought a tree might have fallen, but there was no thud. Then I thought it might have been an ice sheet coming off the roof, so I went outside but could not identify a place where that could have happened. (Most of our snow and ice has melted.) Then I saw that friends were posting on Facebook about a possible earthquake, and on the police scanner, I heard a few reports of the ground shaking.

Curiously, the dogs didn't react.

The U.S. Geological Survey confirms a 4.1-magnitude earthquake 7 miles WNW of Edgefield, South Carolina (about 23 miles north of Augusta, Georgia), centered 2.9 miles below the surface. Event page here.


Never too young

Who says girls can't be interested in electronics?


After snow

We survived, confined to the house more than 48 hours, and nearly so for four days total. The power stayed on, the Internet kept working, I kept working, and the granddaughter kept entertaining us.

The problem was not snow but ice, a heavy accumulation of ice on roads and on cars and buildings. Sheets of ice are sliding off buildings and cars today and doing damage.

[Addendum:] It has been pointed out that a big difference between this week's snowstorm and the one two weeks earlier is that this time, the snow started at night, when people were at home. Two weeks ago, it started during the day, when people were at work and school. The same is true of Snowjam 1982.

The Oconee County Sheriff, as a joke, announced that St. Valentine's Day was cancelled due to the storm. National news picked it up, and now he's getting hate mail from all over the country. Some are saying it makes Georgians look ignorant. Even if it weren't a joke, it wouldn't be ignorant: St. Valentine's Day is a human celebration, not a physical event, and human beings can perfectly well change the date of it.

Happy Valentine's Day, Melody, Cathy, Sharon, and Mary!


Snow #2

Two weeks ago, our "snowjam" was a mild snowstorm with some ice, coupled with Atlanta's notorious inability to handle its own traffic even under the best of conditions.

Now we're having something worse. The University of Georgia took the unprecedented step of announcing on the evening of Feb. 10 that it would be closed on the 11th. (Such announcements are normally made early on the morning of the day of closure.) The National Weather Service is using language it has never used before — we had a winter storm warning, superseded by an ice storm warning. Today (the 11th) we have only had some snow and rain, but tonight, ice is going to start condensing on trees, power lines, and pavement. It should be exciting. Especially with Cathy, Nathaniel, and baby Mary here for a visit!


Lisp Machine "Space-Cadet Keyboard"

Back in the 1980s, the Institute for Artificial Intelligence (or rather its predecessor, the Advanced Computational Methods Center) had three LMI Lisp machines housed in a single box. These were special-purpose minicomputers, programmed in Lisp and designed, from the CPU up, for object-oriented programming. (Almost all present-day CPUs are designed for something very much like the C language, which is not object-oriented.)

The keyboard of the Lisp machine was quite a sight. Here's what it looked like:

As far as I know, some of these keys were never actually assigned meanings. Note the wild character set, and the eight "Bucky bits" (Ctrl, Meta, Super, and Hyper on each side, all separately readable by the CPU). For more about these strange keyboards, click here.

I don't know why the Institute only has one of the three original keyboards. I certainly don't have the others. They are quite valuable artifacts now.

(Photo by Charles Wardell, visiting the Institute on February 7.)

Granddaughter time

Some other activities are on hold while we enjoy a visit from Mary and her parents and even her dog Tycho (whom you have seen in these pages many years ago, when he was our dog).


Start of an avalanche

The CVS pharmacy chain has announced plan to stop selling tobacco products. I think this was a wise decision, and I also think it's the start of an avalanche.

The reason is, there are indications that they have economic motives, not just a concern for health. They're just not selling as many cigarettes as they used to, and they'd rather do something more profitable with the same amount of space and labor.

That doesn't make their decision any less virtuous, of course. But it does mean that a lot of other merchants may quickly follow suit. This may be the hot new trend of 2014.


The Anthropic Principle

One of the least satisfying parts of present-day cosmology, to me, is an assertion called the Anthropic Principle.

It's supposed to explain why the universe is able to support intelligent life. After all, if any of several fundamental physical constants were even slightly different, we couldn't have existed. Everything would be either too hot and gaseous or too cold and inert, or in some other way, the conditions necessary for life (and other complex chemistry) would not be met.

The Anthropic Principle says: The universe has to support intelligent life, because if it didn't, we wouldn't be here to observe it.

I think that is trivially true but not much of an explanation. Here is an analogy.

The other day I lost my jacket, and then I eventually found it at the gymnasium where I exercise.

A reasonable person might ask why my jacket was at the gym.

A satisfying answer would be that I left it there the previous day.

But an answer in the style of the Anthropic Principle would be this: The jacket had to be at the gym because that's where I was looking when I found it.

Not very satisfying, is it?

Ham and Rye, er, Nye

I didn't watch the debate between Ken Ham and Bill Nye about young-earth creationism. Others tell me that the two sides didn't really engage — it was more of an exchange of assertions. But I'm glad to hear that Mr. Nye pointed out that numerous Christian believers are not young-earthers; and Mr. Ham pointed out that a correct opinion about the age of the earth is not necessary for salvation.

I was, of course, questioned by lots of people immediately after the debate, and I want to make two observations.

First: Non-Christians may not realize that the Bible is far from clear about the age of the earth. There is no Bible verse that says how old the earth is. Jesus and the Apostles are never quoted as saying "Four thousand years ago, when the earth was created..." or anything like that. Quite a bit of calculation is needed to extract an age of the earth from the Bible, and you have to assume that the numbers you're adding up are complete and are intended to be used that way.

Second: I've seen two styles of thinking. One of them, which is mine, is to weigh evidence and say after a while that one alternative seems more likely than the other. The other style of thinking is to demand The Answer Right Now and not tolerate any further questioning.

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