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Relativity goes to the dogs

Teaching relativity to a dog may sound like a hopeless mental exercise, but physics professor Chad Orzel says it actually makes the job of teaching relativity to humans easier.

"It makes the whole thing seem much more approachable," Orzel explains. "If you think like a dog, dogs have fewer preconceptions about how things work."

And Orzel's dog, a German shepherd mix named Emmy, won't let him get away with hand-waving gobbledygook. "A lot of the things that she interjects with, those are points where people reading along would say, 'Wait a minute! That doesn't make sense!'" he said.

Of course, Orzel isn't really teaching relativity to his dog. Rather, Emmy serves as the straight man — er, dog — for a scientific dialogue that makes the equations go down more easily. Such dialogues are standard rhetorical devices that go back to Democritus, Socrates, Plato and all those cats in ancient Greece. It's a technique that Orzel used to crowd-pleasing effect in his 2009 book about quantum mechanics, "How to Teach Physics to Your Dog" — and now Emmy is back for more in the newly published sequel, "How to Teach Relativity to Your Dog."

"If you've already talked about quantum physics, relativity is the obvious way to go," Orzel told me. "It's the other great theory of modern physics."

Orzel, who teaches physics at Union College in New York, said that Albert Einstein's special and general theories of relativity can actually be boiled down to one sentence. "All of the weird stuff you hear about E=mc2, clocks running slow when they move, time moving at different rates near a black hole ... all of that weird stuff is just a consequence of the fact that the laws of physics do not depend on how you're moving," he said.

And if there's one thing dogs know a lot about, it's moving. So Orzel casts his explanations of the weird stuff in terms a dog just might be able to understand: For example, when he refers to the speed of light in a vacuum as remaining constant, no matter how it's measured in a moving frame of reference, he doesn't use the standard example of moving rocket ships. Instead, Orzel talks to Emmy about bunnies, cats and dogs in motion.

At times, Emmy tries to jump into the driver's seat with her inquiries into the Unified Theory of Critters, or her plans to build the Superconducting Kibble Collider and search for the bacon boson. ("It's responsible for making other kinds of particles yummy," she explains in the book.) Then it's Orzel's job to tug on the leash and get Emmy's head back in the game. And after a chuckle or two, we're ready to press on as well.

"Because of the dog, I'm able to get away putting some stuff in there that I otherwise wouldn't be able to," Orzel told me. "You can put in some heavy stuff and lighten the tone quite a bit."

That's not to say Orzel has turned relativity into a romp in the park. The book still poses quite a few mental agility trials — particularly when it comes to the counterintuitive aspects of relativistic phenomena, such as the famous "twin paradox." But as much as possible, Orzel highlights the concrete, real-world examples of relativity at work, such as the fact that a height difference of just 12 inches has an ever-so-slight impact on timekeeping, due to the relativistic effects of our planet's gravitational field. The same effects have to be accounted for in GPS satellite navigation systems.

"That shows that this isn't purely some incredibly exotic thing," Orzel said. "It's something that happens in everyday situations. It's just that the effects are usually too small to measure."

So now that Chad Orzel and his dog Emmy have run circles around the two great pillars of modern physics — quantum mechanics and relativity theory — what's next?

"We'll have to see what the dog wants to talk about," Orzel joked. "A few people have asked about statistical physics, but I'm thinking I don't know if even the dog wants to do that."

More about Einstein and relativity:

Alan Boyle is's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter or adding Cosmic Log's Google+ page to your circle. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for other worlds.