## An addictive game

I have spent too much time playing this game.

## R in the news

I’m sure everyone and his brother will be posting a link to this article from Steve McNally’s blog on Forbes. The post contains a lot of interesting links, as do the comments.

## Impressions of Moscow

I emailed a friend today that this city is pretty much as I expected: a mixture of Soviet-style architecture and beautiful old churches and palaces from the czarist era. As a slogan for the local tourism industry, it just might work: Moscow. It’s just what you expected.

Since I will only be here for two days there isn’t much time to see the sights. Today I walked to Red Square, which is a few blocks from my hotel. The first obstacle was crossing Tverskaya and Okhotny Streets. There were no crosswalks that I could see. Then I noticed a little sign with a stick figure walking down steps, and figured it out: pedestrian underpasses, tied in with subway entrances. Nearly lost my way in the maze of tunnels and shops down below, but finally emerged on the other side of the street. Walked past souvenir stalls and a Vladimir Lenin impersonator who would let you take his picture for 100 rubles.

Red Square looked pretty impressive with the setting sun reflecting off the spires of St. Basil’s cathedral. Took a few photos, then wandered into the Gum department store. In a souvenir shop I decided that even in rubles, the cheapest items were too expensive for my budget. I figured I could afford 100 rubles so I had my photo taken with some guys dressed up like medieval Russian knights. Decided to pass on the ersatz Lenin. I’d rather see him “in the flesh” in his tomb. I’ll try to get there tomorrow if I have time.

I was too jet lagged to do much more walking. My legs still feel like rubber after being cramped up in tourist class for 10 hours. Добрый вечер!

Moscow

## The Hacker’s Diet

I’ve struggled a bit with my weight over the years. I try to keep my BMI around 25, but if I don’t watch what I eat it tends to creep upwards towards 27 and even 28 before I even notice. Hence I’m always looking for new techniques to control my diet. This morning I came across an on-line book called The Hacker’s Diet. Written by John Walker, the founder of Autodesk, Inc., it’s a geeky, data-driven approach to maintaining your weight.

I liked this book right away, because Walker seems to have come to some of the same conclusions I’ve reached over the years. First of all, what you eat makes little difference to your body. Whole wheat, organic, natural, vegetarian, high carb, low carb, raw, Paleolithic or Neolithic, it doesn’t matter. Human beings are omnivores, and we can thrive on almost anything. Weight control is all about calories, and to lose weight you have to eat fewer of them. As an aside, take look at this article about a guy who lost 27 pounds on a diet of Twinkies and Doritos.

I’ve also come to the conclusion that while exercise is great for maintaining health, it has little effect on your weight. The book makes this clear: there just aren’t enough hours in the day to perform enough exercise for it to have a significant effect on your weight. Walking for an hour burns as many calories as there are in a single donut. So why not just skip the donut?

Not long ago (see this post), I came to the conclusion that dieting is a matter of weight, not calories. I still think there’s something to this idea — after all, there’s nothing relativistic happening in our bodies, so the principle of conservation of mass has to hold — but The Hacker’s Diet, and this figure showed me that the situation is a bit more complicated. The intake and excretion of water has too great an effect on the mass balance. As Walker writes:

On a day to day basis, the water you consume, whether directly in beverages or as part of the foods you eat, and the water you excrete in your various excursions to the hydraulic accommodations, dwarfs the weight of the food you eat and the solid waste you dispose of … Most of the changes in weight you see have nothing to do with how many calories you’re eating or burning. Instead, all you’re seeing is how many pounds of water happen to be inside (your body) at the moment.

In addition, foods vary greatly in the amount of water they contain, so you can’t focus strictly on the mass of what you’re eating.

As far as I can tell — and I haven’t read all the way through yet — the diet depends on calorie counting and daily tracking of weight, coupled with exponential smoothing to even out the daily variations. It looks very promising.

## Something new under the sun

Interesting article about a new type of heat engine that could double the efficiency of photovoltaic power generation and make it competitive with coal. Apart from the exciting technical possibilities, it’s a wonderful rags-to-riches story of a poor kid from Mobile, AL.

Other links for background: 1) Wikipedia article about the Johnson thermoelectric energy converter. 2) Web page for Johnson ElectroMechanical Systems.

## The mathematics of weight loss

There’s something about the following that doesn’t seem quite right:

The mathematics of weight loss is, in fact, quite simple, involving only subtraction. “Take in fewer calories than you burn, put yourself in negative energy balance, lose weight,” says Braun, who has been studying exercise and weight loss for years. (from this recent article)

I’ve read variations of that statement for years, and always assumed it to be a basic truth. However, after reading that article it occurred to me that there’s nothing relativistic happening at the macro scale in the human body: energy is not converted into mass, and mass is not converted into energy. So why the focus on calories? Dieters are trying to lose body mass, not energy.

Which weighs more: a ton of feathers or a ton of bricks? I’ll bet you fell for that one the first time you heard it (probably back in elementary school if you’re like me). The dieting analogy would be as follows: which will cause you to gain more weight: eating a pound of spinach or a pound of steak? You’ll be one pound heavier after consuming either one of course.

Which is not to say that eating steak is the same as eating spinach. The spinach contains more water, which your body will eventually excrete (unless you happen to be dehydrated). But why not think in terms of a mass balance instead of an energy balance? A simple mass balance for the human body would look something like this:

$\Delta m = \Delta m_i - \Delta m_o$

where m is your body mass, mi is what you drink and eat, and mo is what you excrete. What this says in words is that the change in body mass over a given period of time equals what you consume, minus what you excrete.

That is the basic equation of weight loss, and it’s not a simple subtraction problem because there are two unknowns. If I eat a pound of steak, nobody can tell me precisely how much of that pound I will eventually excrete and how much my body will retain. It all depends, certainly, on how much exercise I do. But it also depends on my rate of metabolism — that is, how many calories my body consumes during its resting state. It also depends, I’m sure, on what my body happens to need at the moment. If I’m already full, my body doesn’t need the steak, so most of the mass will be excreted. But if I’m hungry and haven’t eaten in a while, my body will retain as much of that mass as it can and convert it into nutrients for my cells.

## On the hot hand in basketball

I always thought pareidolia involved seeing faces (e.g., Jesus in a tortilla) but Wikipedia defines it as a psychological phenomenon involving a vague and random stimulus (often an image or sound) being perceived as significant. By this definition, it’s something a lot of sportscasters (and many sports fans) are guilty of. How many times have you heard that a certain player is “on a hitting streak” or has a “hot hand”? This article from Skeptic examines the role of irrational thinking in basketball and other sports.