Seth's Blog

ROBERTS I have some questions about details of the book. What was the hardest part of writing the book? . . . there were no hard parts?

MLODINOW Well, I’m thinking about it and also thinking about how I interpret the word ‘hard.’ Usually ‘hard’ would mean that you’re struggling with it and I’m not sure I exactly struggled with any particular part, in a sense of . . . with all the negative connotations of the word ‘struggle,’ where I’m unsure of victory and battling and becoming exhausted and fear for my life.

I guess the part that comes to mind that I had the most doubts about whether I could get through it was the structure of the book because it weaves together three areas that are historically not that smoothly tied together–probability, statistics and the random processes. Or one united subject, like geometry, that you can see the fairly linear development and here it was more intertwined strands. I did have some trouble at first seeing the segue both in concept and tone of the book, from probability to statistics and at the end when I’m talking more about random processes and very specifically about peoples’ lives. To make that a smooth transition so it doesn’t seem like two books, a book on the concepts and another book on peoples’ lives. There was a lot about peoples’ lives in the earlier parts, too, but in the latter parts of the book, I had less and less actual mathematical concepts and almost solely psychology and sociology and discussion of peoples’ lives. Figuring out exactly how to do that–I do remember struggling with that part–I guess that was the hardest part, I would say.

One other difficult thing was that I went back–when I was talking about the Central Limit Theorem and the Law of Large Numbers–I went back and looked at the very specific work that was done by DeMoivre, Laplace, Gauss etc.  That was difficult because what they actually did is not in the form that is often attributed to them today.  I went back and tried to disentangle what they actually showed and tried to figure out what they were thinking, rather than just talking about the modern form of the theorem in textbooks and attributing it to them.

ROBERTS I see.

MLODINOW That took a lot of effort to figure out. I actually went back and found some of the original calculations.

ROBERTS In a library somewhere? In a manuscript?

MLODINOW They’re in academic books–there are several academic books, so I found some academic books (academic press books, I mean) that presented their actual calculations. I went through those in order to figure out and explain the differences between what they actually did and what the offshoot of their work looks like today.

Interview directory.

Every year Saveur magazine has a list of 100 “favorite people, places, and things.” This year’s list is the “home cook edition” — meaning related to home cooking. Only one entry is about fermented food: making wine vinegar, which takes 2 months.

Given that there are hundreds of fermented foods, many much easier to make, this is unfortunate — just as bad as Paul Goldberger, the New Yorker‘s architecture critic, ignoring green buildings on his list of the top ten buildings of 2008. (A museum with a garden on its roof doesn’t count. Green building is about better houses and businesses.)

In an informative op-ed piece in the New York Times, Michael Alderman, an epidemiologist, questions a government campaign to reduce salt in processed food. His piece raises two (wildly different) questions.

1. Several studies have correlated less salt with worse health. Why? Alderman writes:

Nine [observational] studies, looking at a total of more than 100,000 participants who consume as much sodium as New Yorkers do, have had mixed results. In four of them, reduced dietary salt was associated with an increased incidence of death and disability from heart attacks and strokes. In one that focused on obese people, more salt was associated with increased cardiovascular mortality. And in the remaining four, no association between salt and health was seen.

And in the one experimental study that Alderman knows of, “the group that adhered to a lower sodium diet actually suffered significantly more cardiovascular deaths and hospitalizations than did the one assigned to the higher sodium diet.”

Those are useful facts. Alderman gives a few possible explanations. Here’s another one: Several popular fermented foods, including sauerkraut, buttermilk, miso, and cheese, are high in salt, and fermented foods protect against heart disease. I haven’t read the experimental study Alderman describes but it is unlikely that the two groups in that study ate food that was the same in every way except for salt content. What probably happened is that one group was instructed to choose a low-salt diet and the other group wasn’t. The low-salt group ate less salt in part by avoiding high-salt fermented foods (such as cheese).

2. Alderman writes:

[Observational] research can justify action only when multiple studies produce consistent, robust findings across a wide range of circumstances, as the research on tobacco and lung and cardiovascular health has done.

The puzzle is why he writes like this, which I find irritating. Most of the editorial is good, which makes this lapse especially interesting. I call this black-and-white speak, talking as if something complex was black and white and — always associated with this — people on one side are better than people on the other side. In my professional life, I hear black-and-white speak from some statisticians, who divide analyses into “correct” and “incorrect.” According to them you should analyze your data by following a set of black-and-white rules. Here is a less-irritating version of Alderman’s statement:

Successful public health campaigns have been built on observational studies but in the best-known case — the danger of smoking — the findings were consistent and robust across a wide range of circumstances.

See: no need to moralize. Alderman’s statement, of course, is just one example of something very common.

Ben Casnocha on another example of moralizing in the Times.

Pagophagia is an eating disorder where you chew a lot of ice. A friend of mine had it. After she discovered she loved crunching ice cubes, she started going through several trays of ice cubes per day. A trip to Russia, where ice cubes were unavailable, was highly unpleasant. Eventually my friend learned that pagophagia is caused by iron deficiency. When she started eating more iron, her ice craving went away.

Why do we work this way? The evolutionary reason, I think, is that in the ancient world where this tendency evolved, a desire to crunch something was usually satisfied by crunching bones. After you discovered how pleasant it was to crunch bones, you sought them out. Bone marrow is high in iron. Crunching those sought-out bones increased your iron intake.

The umami hypothesis says that we like umami tastes, sour tastes and complex flavors so that we will consume more harmless-bacteria-laden food (which keeps our immune system on its toes). In the ancient environment where these tendencies evolved, in other words, a desire to eat food with these characteristics led us to eat bacteria-laden food. At the Fancy Food Show, I met a maker of sparkling tea who was unable to get enough complexity without using bacteria.

Just as a person with pagophagia chews ice, most of us do one or more of these:

• add monosodium glutamate (e.g., Accent) for umami taste
• add vinegar for sourness (I put a few drops of vinegar in coffee-like drinks)
• add many spices for complexity

The result, I suspect, is that most of us have immune systems with plenty of room for improvement. I stopped getting easy-to-notice colds when I started sleeping better so the high frequency of reported colds (the average American adult gets about three per year) may be a sign that this is true.

• you are your data
• student-eye view of the Chinese educational system

Thanks to Dave Lull.