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Does a Refrigerator Make a Good Faraday Cage?

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The other week, the New York Times reported that NSA whistleblower Edward Snowden was understandably cautious about planning his departure from Hong Kong to Russia (emphasis mine):

“It was a cloak-and-dagger affair. Mr. Snowden wore a cap and sunglasses and insisted that the assembled lawyers hide their cellphones in the refrigerator of the home where he was staying, to block any eavesdropping. Then began a two-hour conversation during which Mr. Snowden was deeply dismayed to learn that he could spend years in prison without access to a computer during litigation over whether he would be granted asylum here or surrendered to the United States.

Wait. What? Why are the cellphones getting chilled? Snowden’s idea, presumably, was that the refrigerator would act as a Faraday cage. As I explained last year when talking about the effectiveness of tin foil helmets, a Faraday cage is an enclosure made up of a conducting material that shields its interior from external electrostatic charges and electromagnetic radiation by distributing them around its exterior and dissipating them. While these enclosures are sometimes actual cages, they come in many forms, and most of us have probably dealt with one type or another. The scan rooms that MRI machines sit in and the shielding on USB cables, for example, both provide protection as Faraday cages. Inside such a cage, signals to and from these lawyers’ cellphones would be blocked, preventing them from being used to surveil the meeting.

In theory, a sturdy metal fridge should make a good Faraday cage. In practice, some fridges don’t really cut a cell phone off from the rest of the world. Make magazine writer Michael Colombo tried it out with his home refrigerator, and was able to make a call to a phone inside of it. He had better results with a metal cocktail shaker.

I put my fridge to the test, too, and got the same result. Calls and data transmissions went right through. I have a glass cocktail shaker, so that's not an option for me if I'm trying to stay hidden. I wondered if there was a decent kitchen Faraday cage available to people like me, or the poor souls who have no cocktail shaker at all.

I lurked on some survivalist message boards for a while (not an activity I can recommend) and learned that a lot of doomsday hobbyists plan on relying on their microwave to protect their electronics if the government/aliens/New World Order tries to mess with them with an electromagnetic pulse. This makes sense, since, unlike a fridge, a microwave oven is actually designed specifically to shield the electromagnetic radiation of microwaves and keep them from getting out of the appliance. If electromagnetic radiation can’t get out, then it shouldn’t be able to get in either.

Sure enough, calls and data sent to my phone while it sat in my old GE microwave never went through. I could see it sitting in there, but there was no ring, no alerts. When I pulled it out, there was no missed call notification, either. So, the next time you need to keep prying eyes and ears away from your phone, your best bet seems to be tossing it in the microwave or a (metal) cocktail shaker. Just don’t forget about it when you heat up some leftovers or make a Manhattan.

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Big Questions
Why Can't Dogs Eat Chocolate?
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Even if you don’t have a dog, you probably know that they can’t eat chocolate; it’s one of the most well-known toxic substances for canines (and felines, for that matter). But just what is it about chocolate that is so toxic to dogs? Why can't dogs eat chocolate when we eat it all the time without incident?

It comes down to theobromine, a chemical in chocolate that humans can metabolize easily, but dogs cannot. “They just can’t break it down as fast as humans and so therefore, when they consume it, it can cause illness,” Mike Topper, president of the American Veterinary Medical Association, tells Mental Floss.

The toxic effects of this slow metabolization can range from a mild upset stomach to seizures, heart failure, and even death. If your dog does eat chocolate, they may get thirsty, have diarrhea, and become hyperactive and shaky. If things get really bad, that hyperactivity could turn into seizures, and they could develop an arrhythmia and have a heart attack.

While cats are even more sensitive to theobromine, they’re less likely to eat chocolate in the first place. They’re much more picky eaters, and some research has found that they can’t taste sweetness. Dogs, on the other hand, are much more likely to sit at your feet with those big, mournful eyes begging for a taste of whatever you're eating, including chocolate. (They've also been known to just swipe it off the counter when you’re not looking.)

If your dog gets a hold of your favorite candy bar, it’s best to get them to the vet within two hours. The theobromine is metabolized slowly, “therefore, if we can get it out of the stomach there will be less there to metabolize,” Topper says. Your vet might be able to induce vomiting and give your dog activated charcoal to block the absorption of the theobromine. Intravenous fluids can also help flush it out of your dog’s system before it becomes lethal.

The toxicity varies based on what kind of chocolate it is (milk chocolate has a lower dose of theobromine than dark chocolate, and baking chocolate has an especially concentrated dose), the size of your dog, and whether or not the dog has preexisting health problems, like kidney or heart issues. While any dog is going to get sick, a small, old, or unhealthy dog won't be able to handle the toxic effects as well as a large, young, healthy dog could. “A Great Dane who eats two Hershey’s kisses may not have the same [reaction] that a miniature Chihuahua that eats four Hershey’s kisses has,” Topper explains. The former might only get diarrhea, while the latter probably needs veterinary attention.

Even if you have a big dog, you shouldn’t just play it by ear, though. PetMD has a handy calculator to see just what risk levels your dog faces if he or she eats chocolate, based on the dog’s size and the amount eaten. But if your dog has already ingested chocolate, petMD shouldn’t be your go-to source. Call your vet's office, where they are already familiar with your dog’s size, age, and condition. They can give you the best advice on how toxic the dose might be and how urgent the situation is.

So if your dog eats chocolate, you’re better off paying a few hundred dollars at the vet to make your dog puke than waiting until it’s too late.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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Big Questions
What is Duck Sauce?
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A plate of Chinese takeout with egg rolls and duck sauce
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We know that our favorite Chinese takeout is not really authentically Chinese, but more of an Americanized series of menu options very loosely derived from overseas inspiration. (Chinese citizens probably wouldn’t recognize chop suey or orange-glazed chicken, and fortune cookies are of Japanese origin.) It would also be unusual for "real" Chinese meals to be accompanied by a generous amount of sauce packets.

Here in the U.S., these condiments are a staple of Chinese takeout. But one in particular—“duck sauce”—doesn’t really offer a lot of information about itself. What exactly is it that we’re pouring over our egg rolls?

Smithsonian.com conducted a sauce-related investigation and made an interesting discovery, particularly if you’re not prone to sampling Chinese takeout when traveling cross-country. On the East Coast, duck sauce is similar to sweet-and-sour sauce, only fruitier; in New England, it’s brown, chunky, and served on tables; and on the West Coast, it’s almost unheard of.

While the name can describe different sauces, associating it with duck probably stems from the fact that the popular Chinese dish Peking duck is typically served with a soybean-based sauce. When dishes began to be imported to the States, the Americanization of the food involved creating a sweeter alternative using apricots that was dubbed duck sauce. (In New England, using applesauce and molasses was more common.)

But why isn’t it easily found on the West Coast? Many sauce companies are based in New York and were in operation after Chinese food had already gained a foothold in California. Attempts to expand didn’t go well, and so Chinese food aficionados will experience slightly different tastes depending on their geography. But regardless of where they are, or whether they're using the condiment as a dipping sauce for their egg rolls or a dressing for their duck, diners can rest assured that no ducks were harmed in the making of their duck sauce.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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