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Saturday, May 21, 2011

How to Teach Physics to Your Dog

This is about the book "How to Teach Physics to Your Dog".

A guy named Chad Orzel with an interesting blog about physics wrote a book about teaching physics to your dog. He was asked about his book. The following conversation followed:

So, why do you talk to your dog about physics?
Lots of reasons, but the main one is that I'm a physics professor. Talking about physics is what I do. Sooner or later I talk to everybody about physics.

OK, but why the dog?
Talking to the dog about physics is worthwhile because it can help me see how to explain physics to my human students. Humans all come at the subject with the same set of preconceptions about how the world works, and what "should" happen, and it can be very hard to shake those off. That's a big barrier to understanding something like quantum physics.

Dogs look at the world in a very different way. To a dog, the world is a never ending source of wonder and amazement. You can walk your dog past the same rock every morning, and every morning, she'll sniff that rock like she's never sniffed it before. Dogs are surprised by things we take for granted, and they take in stride things that would leave us completely baffled.

Can you give an example?
Well, take the dog's bowl, for example. Every now and then, we put scraps from dinner in the bowl when she's not looking, and she's become convinced that her bowl is magic-- that tasty food just appears in it out of nowhere. She'll wander over a couple of times a day, and look just to see if anything good has turned up, even when we haven't been anywhere near the bowl in hours.

This puts her in a better position to understand quantum electrodynamics than many humans.

It does?
Sure. One of the most surprising features of QED, in Feynman's formulation, is the idea of "virtual particles." You have an electron that's moving along, minding its own business, and every now and then, particle-antiparticle pairs just pop into existence for a very short time. They don't stick around very long, but they have a real and measurable influence on the way electrons interact with each other, and with other particles.

You're making this up, right?
No, not at all. One set of these interactions is described by a number called the "g-factor" of the electron, and this has been measured to something like fifteen decimal places, and the experimental measurement agrees perfectly with the theoretical prediction. If there weren't electrons and positrons popping out of nowhere, there's no way you could get that sort of agreement.

So, what's this have to do with the dog?
Well, like I said, the dog is perfectly comfortable with the idea of stuff popping into existence out of nowhere. If a great big steak were to suddenly appear on your dining room table, you'd probably be a little perturbed. The dog, on the other hand, would feel it was nothing more than her due.

So she's perfectly ok with the idea of virtual particles, unlike most humans, who tend to say things like "You're making this up, right?" She was already convinced that there were bunnies made of cheese popping in and out of the backyard, and just regards QED as a solid theoretical justification for her beliefs.

So that's why people should teach quantum physics to their dogs?
Exactly. Also, it's just about the coolest thing ever.

Hope you enjoyed the conversation!

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