The blog of John D. Cook
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From Albert Einstein’s address to the Seventh German Radio Exhibition at Berlin (1930):
One ought to be ashamed to make use of the wonders of science embodied in a radio set, the while appreciating them as little as a cow appreciates the botanic marvels in the plants she munches.
Source: The Science of Radio by Paul Nahin, first edition
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Richard Feynman on imagining electromagnetic waves:
I’ll tell you what I see. I see some kind of vague showy, wiggling lines — here and there an E and a B written on them somehow, and perhaps some of the lines have arrows on them — an arrow here or there which disappears when I look too closely at it. When I talk about the fields swishing through space, I have a terrible confusion between the symbols I use to describe the objects and the objects themselves. I cannot really make a picture that is even nearly like the true waves. So if you have difficulty making such a picture, you should not be worried that your difficulty is unusual.
From The Feynman Lectures on Physics, volume II.
Other Feynman posts:
Richard Feynman and Captain Picard try to prove Fermat’s Last Theorem
Most important event of the 19th century
God is in the details
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This is the most encouraging thing I’ve seen in cancer research in some time: a way to make tumors fluoresce. This allows surgeons to see tumor boundaries.
From TED
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After I finished an electromagnetism course in college, I said that one day I’d go back and really understand the subject. Now I’m starting to do that. I want to understand theory and practical applications, from Maxwell’s equations to Radio Shack.
I’m starting by reading the Feynman lectures on E&M. After that I plan to read something on electronics. If you have resources you recommend, please let me know.
I’ve started new Twitter account, @GrokEM. I figure that tweeting about E&M will help me stick to my goal. My other Twitter accounts post on a regular schedule (plus a few extras) and are scheduled weeks in advance. GrokEM will be more erratic, at least for now. (In case you’re not familiar with grok, it’s a slang for knowing something thoroughly and intuitively.)
Here’s what Feynman said about mathematicians learning physics, particularly E&M.
Mathematicians, or people who have very mathematical minds, are often led astray when “studying” physics because they loose sight of the physics. They say: “Look, these differential equations — the Maxwell equations — are all there is to electrodynamics … if I understand them mathematically inside out, I will understand the physics inside out.” Only it doesn’t work that way. … They fail because the actual physical situations in the real world are so complicated that it is necessary to have a much broader understanding of the equations. … A physical understanding is a completely unmathematical, imprecise, and inexact thing, but absolutely necessary for a physicist.
Heinlein coined grok around the same time that Feynman made the above remarks. Otherwise, Feynman might have said that only studying differential equations is not the way to grok electrodynamics.
Related posts:
What it means to understand an equation
Most important event of the 19th century
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Stigler’s law says that no scientific discovery is named after its original discoverer. Stigler attributed his law to Robert Merton, acknowledging that Stigler’s law obeys Stigler’s law.
Avogadro’s number may be an example of Stigler’s law, depending on your perspective. An episode of Engines of our Ingenuity on Josef Loschmidt explains.
The Italian, Romano Amadeo Carlo Avogadro, had suggested [in 1811] that all gases have the same number of molecules in a given volume. Loschmidt figured out [in 1865] how many molecules that would be.
You could argue that Avogadro’s constant should be named after Loschmidt, and some use the symbol L for the constant in honor of Loschmidt. Jean Perrin came up with more accurate estimates and proposed in 1909 that the constant should be named after Avogadro. Loschmidt made several important contributions to science that are now known by other’s names.
As I’d mentioned in an earlier post, there are some fun coincidences with Avogadro’s number.
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Andrew Gelman added a couple more types of error to the standard repertoire of type I and type II errors. He suggests using type S error to describe a result that gets a sign backward, reporting that A is bigger than B when in fact B is bigger than A. He also suggests using type M error for results that get the magnitude of a result wrong.
Maybe we could add to this list type R for reification error: treating an abstraction as if it were real, forgetting that a model is a model and stretching it beyond its limits.
Related links:
Just an approximation
Floating point error is the least of my worries
The Pretense of Knowledge
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In a recent interview, Gary Taubes calls picking data that support your conclusion “Bing Crosby science.” This comes from a song by Bing Crosby that begins “You’ve got to accentuate the positive, eliminate the negative.”
Taubes uses the phrase to refer specifically to epidemiology, though it applies to all science. He credits “a Scottish researcher” with coining the phrase, but doesn’t say any more about who this researcher was.
Related post:
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Seth Roberts writes this morning:
How can you tell when an expert is exaggerating? His lips move.
Some people will misunderstand his point. Roberts is not saying experts exaggerate their conclusions per se. He’s saying experts exaggerate their confidence in their conclusions.
If an expert says that playing a harmonica decreases your risk of influenza by 10%, she’s probably not making that figure up out of thin air (though I am). There probably was some data that implied the 10% figure. It’s not that the data suggested 5% and the scientist said “Let’s call it 10%.” But the quality and quantity of the data may not justify rushing out to buy a harmonica.
One reason experts exaggerate their confidence is that they may be at a loss for words to explain their degree of uncertainty to a popular audience. Journalists can understand “Harmonica playing is good for you” though they probably cannot understand confidence intervals, Bayes factors, or the differences between retrospective versus prospective experiments. (The experts may not really unstand these things either.)
Another reason for exaggeration is that you don’t get the attention of the press by making tentative claims. This creates an incentive to suppress uncertainty. But even if experts were transparent regarding their uncertainty, there would still be a selection bias: experts who are sincerely more confident are more likely to be heard.
There are numerous other reasons experts may be wrong, some psychological and some statistical.
I liked the first comment on Roberts’ post:
I tended to rate my colleagues partly by how often the words “I don’t know” passed they lips. Often = good.
Related posts:
Three reasons expert predictions are often wrong
The most powerful people are right
Most published research results are false
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If you’re not interested in a subject, do cartoons make it more palatable?
My guess is that cartoons may help keep your attention if you’re moderately interested in a subject. If you’re fascinated by something, cartoons get in the way. And if you’re not interested at all, cartoons don’t help. The cartoons may help in the sweet spot in between.
No Starch Press has given me review copies of several of their Manga Guide books. The first three were guides to the universe, physics, and relativity. I’ve reviewed these here and here. Recently they sent a copy of the newest book in the series, The Manga Guide to Biochemistry.
I’m much more interested in physics than biology, so I thought this would be a good test: Would a manga book make it more interesting to read about something I’m not very interested in studying? Apparently not. It didn’t seem that the entertaining format created much of an on-ramp to unfamiliar material.
It seemed like the information density of the book was erratic. Material I was familiar with was discussed in light dialog, then came a slab of chemical equations. Reading the book felt like having a casual conversation with a lawyer who periodically interrupts and asks you to read a contract.
Someone more interested in biochemistry would probably enjoy the book. Please understand that the title of this post refers to the fact that I find biochemistry uninteresting, not the book. If I had to study a biochemistry book, the Manga Guide to Biochemistry might be my first choice. At times I’ve found biochemistry interesting in small doses, describing a specific problem. But it would be nearly impossible for me to read a book on it cover to cover.
O’Reilly’s “Head First” series is similar to the Manga guide series, though the former has more content and less entertainment. I enjoyed the first Head First book I read, Head First HTML with XHTML & CSS. Maybe I enjoyed it because the subject matter was in the sweet spot, a topic I was moderately interested in. The cartoons and humor helped me stick with a dry subject.
When I tried another Head First book, I was hoping for more that same push to keep going through tedious content. The books clearly had the same template though with different content. What was interesting the first time was annoying the second time, like hearing someone tell a joke you just heard. So at least for me, the Head First gimmick lost some of its effectiveness after the first book.
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Joseph Fourier is perhaps best known for his work studying heat conduction. He developed what we now call Fourier series as part of this work.
I recently learned that Fourier had a personal problem with heat.
Even though Fourier conducted foundational work on heat transfer, he was never good at regulating his own heat. He was always so cold, even in the summer, that he wore several large overcoats.
Source: The Physics Book
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The previous post mentioned that Avogadro’s constant is approximately 24!. Are there other physical constants that are nearly factorials?
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Avogadro’s number NA is the number of atoms in 12 grams of carbon-12. It’s about 6.02 × 1023.
Here are a few fun coincidences with Avogadro’s number.
The first observation comes from here. I forget where I first heard the second. The third comes from Andrew Dalke in the comments below, verified by WolframAlpha.
For more constants that approximately equal factorials, see the next post.
Related posts:
Pi seconds is one nanocentury
There isn’t a googol of anything
Simpler version of Stirling’s approximation
What is the shape of the Earth?
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From Seth Roberts:
If you ignore data, the answer to every hard question is the same: the most powerful people are right. That way lies stagnation (problems build up unsolved because powerful people prefer the status quo) and collapse (when the problems become overwhelming).
Science is far more political than I had imagined before starting a career in science. Data trumps politics eventually, but it may take a long time.
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Last week I stayed in a hotel where I noticed this sign:
This building contains chemicals, including tobacco smoke, known to the State of California to cause cancer, birth defects, or other reproductive harm.
I saw similar signs elsewhere during my visit to California, though without the tobacco phrase.
The most amusing part of the sign to me was “known to the State of California.” In other words, the jury may still be out elsewhere, but the State of California knows what does and does not cause cancer, birth defects, and other reproductive harm.
Now this sign was not on the front of the hotel. You’d think that if the State of California knew that I faced certain and grievous harm from entering this hotel, they might have required the sign to be prominently displayed at the entrance. Instead, the sign was an afterthought, inconspicuously posted outside a restroom. “By the way, staying here will give you cancer and curse your offspring. Have a nice day.”
As far as the building containing tobacco smoke, you couldn’t prove it by me. I had a non-smoking room. I never saw anyone smoke in the common areas and assumed smoking was not allowed. But perhaps someone had once smoked in the hotel and therefore the public should be warned.
Related post:
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