Month: November 2009

Mistaken Consensus in Physics?

Seth Roberts18 Comments

Steven Sheets writes:

I can’t really think of an area in physics where a consensus has been achieved only to be shown to be completely wrong.

Good point. I know little about physics but I tend to agree. Work awarded the Nobel Prize in Physics is more trustworthy than work awarded the Nobel Prize in Medicine, for example. I think a big reason that a consensus presented to the public is wrong is because there is outside pressure to get it right — pressure to find a way to lose weight, pressure to find how to reduce heart disease, and so on. Whereas there is no public pressure to get this or that physics question right. Less is at stake and the physics community can take as long as it wants.

Still, physicists make mistakes and other physicists go along with those mistakes. I can think of three examples:

1. When calculating the charge on an electron, Millikan famously used the wrong value for the viscosity of air. This didn’t prevent those using other methods from getting the same answer.

2. It was a rather bold title: How Nature Works (1996) by Per Bak. Yet the sand avalanche models on which the whole thing was based turned out to be wrong. Actual sand didn’t behave as predicted. There wasn’t consensus in the physics community that Bak was right, but many physicists took him seriously. (As far I can tell from a distance.) I’ve worked on explaining power-law data (the subject of Bak’s book) and the ideas in that book weren’t helpful.

3. Long ago, lots of physicists – if astronomy is part of physics — believed that the sun revolved around the earth.

There’s plenty of pressure and a lot at stake to get climate predictions right. So I think climate models are in the territory where big consensus mistakes are made. As Patrik points out, the story of the Yamal tree-ring data — which I wasn’t thinking of when I wrote the Elizabeth Kolbert post, or I would have mentioned it — is a very good reason to think that what Kolbert writes about climate is less certain than Kolbert thinks.

Three Things Elizabeth Kolbert Doesn’t Know

Seth Roberts28 Comments

A staff position at The New Yorker is the best journalistic job in the world. Elizabeth Kolbert, a very good writer and reporter, has one of them. In the current issue, criticizing Superfreakonomics, she writes:

To be skeptical of climate models and credulous about things like carbon-eating trees and cloudmaking machinery and hoses that shoot sulfur into the sky is to replace a faith in science with a belief in science fiction.

I cannot discuss engineering (“carbon-eating trees”, etc.) but I can discuss science (“climate models”). Here Kolbert shows the same limitation that practically every science journalist shows (the big exceptions are Gary Taubes and John Crewdson): They take the consensus view too seriously. In case after case — so many that it’s hard not to draw sweeping conclusions — the consensus view about difficult topics is more fragile than an outsider would ever guess. It’s not necessarily wrong, just less certain.

Kolbert places too much faith in those climate models. Here are three things Kolbert doesn’t know:

1. For years, as I’ve blogged, Leonard Syme, an epidemiology prof at Berkeley, taught his students to distrust one mainstream public-health conclusion after another. Maybe 12 examples in all. He showed them facts they didn’t know. All of a sudden the picture wasn’t so clear any more. That he could do this in so many cases, one case per week, is what’s telling.

2. If you believe mainstream ideas about weight control, the Shangri-La Diet is absurd. It can’t possibly work. Since it has actually worked in countless cases — more than half the time, as far as I can judge — the experts, it appears, got it utterly wrong. Long before me, Michel Cabanac, a professor of physiology at Laval University, was saying the same thing — that the consensus view about how to lose weight was wrong. No matter how many millions of times journalists repeated it. The Shangri-La Diet merely makes it vividly clear he was right.

3. Hal Pashler and I wrote a paper about how mental models based on fitting data were delusional. The data that supposedly supported them did not. To take seriously a model because it could fit data was a mistake, we pointed out; what matters is correct predictions. It isn’t easy to figure out the predictions of a model with many adjustable parameters; and the modelers in these cases never did. These models were accepted professionally for half a century; perhaps they still are.

It is possible that climate modelers have a different psychology than scientists in other areas — that the evidence for the consensus presented to outsiders is as strong as the scientists involved say it is — but it seems highly unlikely. For example, I doubt the climate models Kolbert places such faith in have been tested (their predictions, not just their fits, compared with reality).

There’s no doubt that carbon dioxide concentration and global temperature are correlated, but you may not know that carbon dioxide concentration lagged temperature for a long time. Because of this, I’m sure the temperature change caused the carbon-dioxide change. It isn’t mysterious; as water changes temperature, the amount of carbon dioxide it can dissolve changes. As water heats, carbon dioxide is released into the air.

This means that something powerful — not carbon dioxide — has been producing changes in global temperature so large they cause carbon dioxide to rise and fall in amounts as large as those we are now worried about. Until we know what this is there is no way to allow for it. To subtract it from observed carbon dioxide and temperature changes, see what remains, and try to draw conclusions from the residuals. And we don’t know what it is, no matter how closely this or that climate model fits data. (How closely they fit data depends on how many parameters they have, not merely how truthful they are. More adjustable parameters –> closer fit.) Until we know what it is, it is entirely possible that this force, not man-made emissions, is behind recent increases in global temperature and carbon dioxide. If man-made emissions are not causing the change in temperature, reducing them is unlikely to do much. (Sure, there are a hundred blog posts dismissing the inconvenient backward lag. I’ve been unable to find even one that addresses the point I’m making here.)

This is like what Richard Herrnstein and Charles Murray failed to understand in The Bell Curve. They had a whole chapter on the Flynn Effect (the large increase in IQ over years) but they failed to grasp that until the Flynn Effect was correctly explained — until we knew what caused it — there was a big environmental contribution to IQ that they didn’t understand. Perhaps it was this powerful environmental factor that caused the between-race differences in IQ that they attributed to genes. They were unable to equate different races for this factor — to take its effect into account.

Herrnstein and Murray might have been smart enough to see the problem — but, in any case, they ignored it. Kolbert is smart enough to understand that the climate scientists she talks to have a vested interest in overstating their case — but, at least in her writing, she ignores this. If she stopped ignoring the vested-interest problem and tried to think for herself — to sort out for herself conflicting claims, to stop believing everything a mainstream thinker tells her — her job would be much harder. (It took Gary Taubes seven long years to write Good Calories Bad Calories.) Given Kolbert’s lack of scientific background (at The New Yorker she originally covered politics), perhaps her job would be impossible. Kolbert’s faith is not in science, as she pompously says, but in scientists.

FDA Hid Research Showing that Aspartame is Dangerous

Seth Roberts10 Comments

Here is a lot of information about this. The commercial name for aspartame is Nutrasweet. Because of worries about its neurotoxicity I switched to Splenda long ago. But if the FDA approval process is so deeply flawed they approved Nutrasweet, how safe is Splenda? In China, I’ve managed to pretty much avoid artificial sweeteners.

More Animal Fat, Better Sleep

Seth Roberts7 Comments

After I wrote about eating a lot of pork fat and sleeping better, David Shackelford commented that he had had a similar experience: After he started eating much more animal fat and meat, he too slept better. (He posted about this before he read my post.) I asked him for details. He answered:

About three weeks ago, I started a carnivorous diet. I did this primarily for its supposed benefit to insulin sensitivity, energy levels, and general health, and also because I wanted to see if it was really possible to thrive on nothing but meat.

Immediately after starting, I noticed that I was sleeping easier, longer, and deeper, and having more vivid dreams than usual. I’ve had a hard time falling asleep for my entire life, usually taking 45 minutes to two hours after going to bed, and occasionally not being able to sleep at all, so this was a very pleasant surprise.

At first I thought that this was due to standing on one foot, which I had started a few days prior, but I stopped one-foot-standing and the effect persisted. The all-meat diet has been pretty great all around-food is delicious, I’ve got a ton of energy, and I’m rarely hungry-but the sleep has been the best part.

Me
21 years old (senior in college)
130-ish lbs
5’4″
12-15% body fat
Moderately active, fairly good shape.

My diet
-Breakfast of 3-4 egg omelette, with 1-2 oz cheese and occasionally bacon.
-Lunch: chicken breast, sausage, or eggs.
-Dinner: 1lb+ steak.
-Snacks: nuts and/or cheese.

Approximate macronutrient composition
Before: 50% carbohydrate / 30% protein / 20% fat (at least half unsaturated olive oil)
After: 60-70% fat (all animal fat), 30-40% protein;10% carbohydrates (nuts and the occasional glass of wine, plus trace amounts in sauces and cheeses). Unsure of my caloric intake; I think it varies between 1500 and 2000 a day.

Other
-I cook chicken, beef, and eggs in butter.
-I drink coffee 1-2 times a day, and tea about once a day.
-I take a multivitamin (I don’t know why), 5,000 IU Vitamin D (I live in Oregon, which gets very little sunlight), and 2.5g fish oil (the grain-fed beef I eat has low 3:6 ratios; if I could afford grass-fed, I probably wouldn’t need the fish oil).
-I let the diet go on weekends, for the sake of social life. I probably have 3-5 drinks on Friday and Saturday night, as well as some junk food (pizza/chips/fries). I feel like I don’t sleep quite as well on these days, but there are so many confounding variables (alcohol, staying up later than usual, seeing faces later into the night, sex) that isolating a cause of the difference is tough.

Exercise
-I lift weights for about 30 minutes, twice a week.
-I go out social dancing for about four hours, once to twice a week.
-Sleep does not seem to vary with whether I exercise or not.

He blogs about this at meatsaur.us. His story is more evidence that the animal fat/sleep connection is cause and effect (animal fat –> better sleep), and suggests that the effect is not limited to me.

My self-experiment about this.

Why Are Colds and Flu More Common in Winter?

Seth Roberts8 Comments

The effect is so large, so easy to notice, it is enshrined in the word cold. We get far more colds and flu in the winter (“flu season”) than in the summer. In this excellent interview, epidemiologist Thomas Jefferson asks:

Why, for example, do we not get influenza in the summertime?

All of the possible explanations listed in this Wikipedia article assume that it is cold weather that makes flu more common in winter. However, an impressive 1981 study found that flu peaked during the light minimum, not the temperature minimum, contradicting all of these explanations.

My proposed explanation is that flu is less common in the summer because people sleep better during the summer. They sleep better in the summer because they get more morning light. More morning light causes your circadian system to have a greater amplitude, which means you sleep more deeply. Better sleep –> better immune function. When I started to sleep much better, I stopped getting noticeable colds and flu.

When I wrote my paper it was essentially impossible to test my idea. You need to measure a lot of sleep — and sleep scientists, intent on making it hard to do what they do, have made this nearly impossible. Perhaps it will soon be easier. To begin with, to test my idea you’d need to improve sleep somehow. To get more light exposure during winter is easy enough with a light box but measuring quality of sleep is much harder. Maybe FitBit (which will start shipping in a few months) will make this possible. I tried using SleepTracker to measure my sleep but after a few months I gave up. There were four big problems: 1. The interface didn’t work very well. It was often hard to get the data from the device into my computer. 2. The whole thing wasn’t designed to measure sleep, it was designed to wake you at a better time than you would wake up without it. 3. The way it measured sleep was a secret. 4. The output — the measure of sleep — was binary. All you were told was whether movement was above or below some threshold. And I had no idea how that threshold was determined.

Assorted Links

Seth Roberts4 Comments

Thanks to Carl Willat, Peter McDonnell, Stephen Marsh, and someone else whose name I cannot find.

How to Base Medicine on Evidence

Seth RobertsLeave a comment

The thing to notice about what the New York Times calls “ the evidence-based medicine practiced at Intermountain hospital” is how different it is than the movement called evidence-based medicine. The Intermountain stuff, above all, is not black-and-white thinking. It is a good example of what the opposite looks like. The rules aren’t simple, they are complex, and not fixed. It is what engineers in other areas have been doing since Deming.

So many scientists — not to mention everyone else — are completely paralyzed, rendered completely useless, by their black-and-white thinking. It feels good to them — they love the certainty of it, and the power it gives them to look down on others — and they never quite realize what it has done to them. The notion of using evidence to improve health care made perfect sense — until black-and-white thinkers got a hold of it.

Any class in scientific method should be at least half about avoiding black-and-white thinking. They never are.

Saturated-Fat Epidemiology

Seth Roberts22 Comments

Here, at Free the Animal, are three scatterplots that show better health (less heart disease, less stroke) correlated with more saturated fat (= animal fat) in the diet. Each point is a different European country (Albania, Bulgaria, etc.). Small and large countries show the same relationship.

The obvious confounding is with wealth — rich people eat more meat than poor people. Were this data submitted for publication, I imagine someone would say how dare you fail account for that! and reject the paper. That would be a mistake. Because it is hard to look at this data and continue to think that saturated fat is the evil it is made out to be. And of course whatever the weaknesses of my sleep/fat experiment (which showed animal fat improved my sleep), confounding with wealth was not one of them.

Jiaweishop.com Scam

Seth Roberts38 Comments

If you look on this blog you will find several other website names that this site has used to scam people, such as myshopinsun.com. You will pay via PayPal, complain to PayPal, PayPal will “investigate”, decide you were right — and not give you your money back. That PayPal keeps helping whoever is behind this is curious and infuriating to anyone scammed.