Monthly Archives: October 2010

The Magnetism of Light

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Measuring the Magnetism of Light

When light interacts with matter, the dominant action is often a “shaking” up and down of electrons in response to the electric field. This interaction is typically 10,000 times larger than the “swirling” action from a light wave’s magnetic field. The case is different in metamaterials, which contain small components like metal rings that are often tailored to have an enhanced response to magnetic fields. Thanks to this sensitivity, light traveling through a metamaterial can bend in unusual ways, making feasible such devices as super-lenses and invisibility cloaks.

I See What You Did There

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Sound can leap across a vacuum after all

I saw this retweeted by Jennifer, but sorry — No, it can’t.

When a sound wave reaches the edge of one crystal, the electric field associated with it can stretch across the gap and deform the crystal on the other side, creating sound waves in that second crystal (Physical Review Letters, vol 105, p 125501). “It is as if the sound waves don’t even recognise the vacuum – they just go through,” says Prunnila.

This is the kind of writing that really, really annoys me. Redefining terms in order to sensationalize the material. Sound doesn’t jump across the vacuum barrier — an electric field does, and that’s perfectly cromulent. The electric field causes the piezoelectric transducer on the other side to vibrate and recreate the sound. Neat. But if this counts as sound going through a vacuum, then transmissions using a satellite has to count, too. We’ve been doing this for more than 50 years.

Experts are Called "Experts" for a Reason

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Don’t Listen to the Newspapers

Presented in terms of the climate “debate,” but the thrust is true in general.

97.6% of publishing climatologists, 100% of studies in scientific journals, and every scientific organization in the world now agree that humans are changing the climate.

Compare this to the media coverage of climate change. The majority of articles in respected newspapers like The New York Times or The Wall Street Journal give roughly equal time to the “two sides” of the so-called “scientific debate”. Balance in journalism is all very well when the issue is one of political or social nature, but for matters of science, giving fringe opinions the same weight as a robust consensus is misleading. Being objective is not always the same as being neutral.

(emphasis added, just because)

The Relativity of Wrong

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Isaac Asimov: The Relativity of Wrong

“If I am the wisest man,” said Socrates, “it is because I alone know that I know nothing.” the implication was that I was very foolish because I was under the impression I knew a great deal.

My answer to him was, “John, when people thought the earth was flat, they were wrong. When people thought the earth was spherical, they were wrong. But if you think that thinking the earth is spherical is just as wrong as thinking the earth is flat, then your view is wronger than both of them put together.”

The basic trouble, you see, is that people think that “right” and “wrong” are absolute; that everything that isn’t perfectly and completely right is totally and equally wrong.

This is old-ish, but I just ran across it; I had written something vaguely similar recently in response to a Feynman video about there being varying degrees of wrong, but Asimov goes into some nice detail in quantifying “wrong,” and filling in the shades of grey to contrast with the black-and-white of right vs. wrong. It is reminiscent of George Box’s quote, All models are wrong, but some are useful