Monthly Archives: August 2009

Death to Exponential Growth

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Your body wasn’t built to last: a lesson from human mortality rates

What do you think are the odds that you will die during the next year? Try to put a number to it — 1 in 100? 1 in 10,000? Whatever it is, it will be twice as large 8 years from now.

This startling fact was first noticed by the British actuary Benjamin Gompertz in 1825 and is now called the “Gompertz Law of human mortality.” Your probability of dying during a given year doubles every 8 years. For me, a 25-year-old American, the probability of dying during the next year is a fairly miniscule 0.03% — about 1 in 3,000. When I’m 33 it will be about 1 in 1,500, when I’m 42 it will be about 1 in 750, and so on. By the time I reach age 100 (and I do plan on it) the probability of living to 101 will only be about 50%. This is seriously fast growth — my mortality rate is increasing exponentially with age.

This is News?

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Tyrannosaurus rex ‘picked on baby dinosaurs and ate them whole’

Research into the predatory habits and diet of the biggest of the dinosaurs has concluded that T.rex and other members of its carnivorous theropod family preferred to dine on juveniles, preferably small enough to eat whole.

It shatters the notion that the giant battled with animals of a similar or even larger size, an image reinforced by its portrayal in Steven Spielberg’s 1993 film Jurassic Park.

Really? Jurassic Park, a work of fiction wherein the T. rex never battled anything of similar, much less larger, size? And why would anyone expect T. rex to behave any differently than modern carnivores, who prey on the young and weak? Certainly not the researchers:

Dr Hone, who works at the Institute of Vertebrate Palaeontology and Palaeoanthropology in Beijing, said: “Modern predators mainly attack vulnerable, young animals as they are inexperienced in evading predators, and this was probably the same in dinosaurs. Young prey are easier to bring down and the risk of injury to the predator is much lower.

Eye of Newt and Toe of Frog

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Ingredients: What’s in the stuff we buy?

A project started by the question, “Why is there salt in my shampoo?”

There are thousands of chemical compounds in the ingredients lists of products we buy every day. Knowing what each one is doing in the product has obvious benefits in comparison-shopping. However, it also provides a sneaky way of teaching simple chemistry to people who had no idea they would find it so interesting. I am always looking for ways to make science more interesting to people who think it is only for people who use masking tape on their eyeglasses.

Here’s part of an example —

Sodium benzoate is used in acidic foods and products to control bacteria, mold, yeasts, and other microbes. It interferes with their ability to make energy.

Because it only converts to benzoic acid in acidic environments, it is not used for its anti-microbial action unless the pH is below about 3.6. In the food industry, it is used in items such as jams, salad dressing, juices, pickles, and carbonated drinks.

Thinking Outside the Ball

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Physicists trap light in a bottle

To get light into an optical cavity, it has to fit. That is, when the photon travels a complete circuit of the sphere, it must travel a whole number of half-wavelengths. The spheres are tiny, so the color difference between two wavelengths that fit is huge. This becomes a problem because we can’t precisely control the size of the spheres during manufacture, and nature chooses which colors of light atoms will interact with—the two rarely end up matching.

The usual solution is to make a bajillion spheres and find one that is close to right. Then you can heat the sphere so that it expands until you get to exactly the right color. It would be much better to just have a resonator that could adapt itself to any color of light.

Treekiller!

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How did I miss this? XKCD is coming out (no, not like that) — as a real book. Oh, the humanity! Trees! RUN FOR YOUR LIVES! Oh, gawd, they can’t!

NY Times: When Pixels Find New Life on Real Paper

“It’s not supposed to be a punch line, but hopefully if you didn’t laugh, you’ll laugh at this,” he said. The title text will appear where the tiny copyright notice would appear on a traditional strip.

Does that mean that the book won’t carry a traditional copyright and instead take its lead from the online comic strip itself, which Mr. Munroe licenses under Creative Commons, allowing noncommercial re-use as long as credit is given?

“To anyone who wants to photocopy, bind, and give a copy of the book to their loved one — more power to them,” he said. “He/She will likely be disappointed that you’re so cheap, though.”

Randall notes on his blag

Note: Some of the stuff in the article is no longer accurate – since then, I’ve gone back and redone the layout and comic selection myself.