The new age of ignorance

Another interesting recently released book is discussed by Tim Adams in The Observer today in an article titled “The new age of ignorance,” which begins:

We take our young children to science museums, then as they get older we stop. In spite of threats like global warming and avian flu, most adults have very little understanding of how the world works. So, 50 years on from CP Snow’s famous ‘Two Cultures’ essay, is the old divide between arts and sciences deeper than ever?

The book discussed is The Canon: A Whirligig Tour of the Beautiful Basics of Science by NY Times science journalist Natalie Angier. As a little test of our scientific literacy, Tim Adams also interviewed scientists and non-scientists with 6 basic science questions:

We asked three writers, three scientists (2 biologists and a geologist) and two broadcasters to answer six basic scientific questions, and their answers appear to confirm the arts/science divide.

One of the questions was one I asked in my own dissertation study, more or less: “What happens when you turn on a light?” Interestingly, even the scientists didn’t answer the question that well, although in all due respect none of them were physicists or electrical engineers. Even the “answer” given in the article still hides a popular misconception:

Answer: The switch controls the flow of electricity through a circuit – a complete, unbroken loop through which electric charges can move. When the light switch is on, these electric charges can move in an endless loop. This loop begins at a power station where the charges pick up electric energy. They then flow through wires to the light switch, then to the light bulb where they deliver their electric energy, and finally back to the power company to obtain more energy.

The misconception is that when you flip a switch, electrons travel from the power station all the way to your house (at light speed) to turn things on. This misconception derives from another misconception: That wires are like empty pipes. In fact, they are “filled” with electrons even when the circuit is off. It is more like a closed water or hydraulic pipe system, not an empty pipe system. When you flip the switch, it is like opening a valve or connecting two pipes, which simply allows the electrons already inside the wire to move. That motion (which is slow, not at light speed) allows transfer of energy (which happens fast, via electrical and magnetic fields). It is like pushing a train on a circular track. Almost as soon as you push a car at one end, the car at the other end and the cars in between move too, even though the cars themselves are not moving fast at all. So when you flip on a switch, electrons don’t bolt from the power station down to your house at light speed and then turn on the lights.

Posted in education
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