Fun family science project — electric lighting from trash

The Joule Thief is a way of producing enough electricity to run small, but useful, electric lights using cast-off trash like pop-can tabs and "dead" batteries. It's especially handy in the Himalayas, writes inventor and Google Science Fair judge T.H. Culhane. There, electricity is a precious resource. But the components needed to build a Joule Thief are abundant, thanks to climbers and tourists who leave behind all sorts of surprisingly useful litter.

Last week, Culhane joined a G+ hangout sponsored by National Geographic and Girlstart to talk about the value in things we throw away and walk viewers through the construction of their very own Joule Thief. You can watched the video of the event, or read the instructions for building a Joule Thief at Culhane's blog.

The fact that the Joule thief allows one to run a 3V LED from a 1.5 or 1.2 Volt battery would itself be astounding, because it means you only need half the number of batteries to get the same light.

Some of you are thinking "wait, maybe it enables you to use a single 1.5 volt battery to light a 3V LED instead of the usual two, but doesn't it just make that battery last half as long? Great question, but the answer is that the Joule Thief, which works by building up and collapsing a magnetic field around the torus (which acts as an electromagnetic inductor) actually is more efficient than using a battery directly because it PULSES the energy to the LED.

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How experimental design can create conflicting results

Is coffee bad for you or good for you? Does acupuncture actually work, or does it produce a placebo effect? Do kids with autism have different microbes living in their intestines, or are their gut flora largely the same as neurotypical children? These are all good examples of topics that have produced wildly conflicting results from one study to another. (Side-note: This is why knowing what a single study says about something doesn't actually tell you much. And, frankly, when you have a lot of conflicting results on anything, it's really easy for somebody to pick the five that support a given hypothesis and not tell you about the 10 that don't.)

But why do conflicting results happen? One big factor is experimental design. Turns out, there's more than one way to study the same thing. How you set up an experiment can have a big effect on the outcome. And if lots of people are using different experimental designs, it becomes difficult to accurately compare their results. At the Wonderland blog, Emily Anthes has an excellent piece about this problem, using the aforementioned research on gut flora in kids with autism as an example.

For instance, in studies of autism and microbes, investigators must decide what kind of control group they want to use. Some scientists have chosen to compare the guts of autistic kids to those of their neurotypical siblings while others have used unrelated children as controls. This choice of control group can influence the strength of the effect that researchers find–or whether they find one at all.

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Obedience and fear: What makes people hurt other people?

Stanley Milgram's "Obedience to Authority" experiments are infamous classics of psychology and social behavior. Back in the 1960s, Milgram set up a series of tests that showed seemingly normal people would be totally willing to torture another human being if prodded into it by an authority figure.

The basic set-up is probably familiar to you. Milgram told his test subjects that they were part of a study on learning. They were tasked with asking questions to another person, who was rigged up to an electric shock generator. When the other person got the questions wrong, the subject was supposed to zap them and then turn up the voltage. The catch was that the person getting "zapped" was actually an actor. So was the authority figure, whose job it was to tell the test subject that they must continue the experiment, no matter how much the other person pleaded for them to stop. In Milgram's original study, 65% of the subjects continued to the end of the session, eventually "administering" 450-volt shocks.

But they weren't doing it calmly. If you read Milgram's paper, you find that these people were trembling, and digging nails into their own flesh. Some of them even had seizure-like fits. Which is interesting to know when you sit down to read about Michael Shermer's recent attempt to replicate the Milgram experiments for a Dateline segment. Told they were trying out for a new reality show, the six subjects were set up to "shock" an actor, just like in Milgram's experiments. Read the rest

Evidence suggests: Don't bother brining your turkey

J. Kenji Lopez-Alt, the chief creative officer at the Serious Eats Blog, is a mad kitchen-science genius. Here at BoingBoing, we've posted about his past experiments demonstrating that there's no reason to waste money on expensive cleavers; that foie gras isn't necessarily evil; and that McDonald's hamburgers will, in fact, rot (under the right conditions).

Now, just in time for your Thanksgiving planning, Lopez-Alt puts turkey brining to the test, running a series of trials comparing the meat-moistening results of various brining solutions, dry salt rub, tap water, and a plain control turkey breast. His conclusion: Don't bother with the brine. Not because it doesn't work — brined turkey does produce nice, moist meat. But because it also produces meat that's kind of soggy. You'll get nearly as good results, without the texture problems, out of dry salt.

I particularly enjoyed this part, where Lopez-Alt explains why the results of brining with water aren't any different from the results of brining with broth.

There are two principles at work here. The first is that to the naked eye, broth is a pure liquid, in reality, broth consists of water with a vast array of dissolved solids in it that contribute to its flavor. Most of these flavorful molecules are organic compounds that are relatively large in size—on a molecular scale, that is—while salt molecules are quite small. So while salt can easily pass across the semi-permeable membranes that make up the cells in animal tissue, larger molecules cannot.

Additionally, there's an effect called salting out, which occurs in water-based solutions containing both proteins and salt.

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Water bubbles orbiting a knitting needle on the ISS

Astronaut Don Pettit is a national treasure. He's been to space three times—once for a six-month stay on the ISS. On every mission, he's found time to make huge contributions to the public communication of science, including making a series of amazing "Science Saturday" videos and inventing (from spare parts he found lying around the ISS) a system to help the space station take clearer, sharper pictures of the Earth at night.

Pettit went to space with an international crew in December 2011 and is currently in space. This new video—where he demonstrates the way a small electric charge can manipulate the behavior of water droplets in microgravity—is a great addition to his oeuvre!

Thanks for Submitterating, James!

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Invention of the space-coffee-cup Saturday Morning Science Experiment: Gravity Is For Suckers Saturday Morning Science Experiment: Gyroscopes in space HOWTO Drink Coffee in Space (video demo) Astronaut in Antarctica to conduct fun experiments for the public Soap bubbles in space: cool online experiment logs from the ISS Astronaut describes what space smells like Five questions with astronaut Rex Walheim Read the rest