The dog is standing at the window, wagging her tail excitedly. I look outside, and the back yard is empty. “What are you looking at?” I ask.
“Bunnies made of cheese!,” she says. I look again, and the yard is still empty.
“There are no bunnies out there,” I say, “and there are certainly not any bunnies made of cheese. The back yard is empty.”
“But particles are created out of empty space all the time, right?”
“Have you been reading my quantum physics books again?”
“It’s boring here when you’re not home. Anyway, answer the question.”
“Well, yes, in a sense. They’re called ‘virtual particles,’ and the zero-point energy of the vacuum can occasionally manifest as particle-anti-particle pairs.”
“See?” she says, wagging her tail harder, “Bunnies made of cheese!”
“I’m not sure how that helps you,” I say. “The virtual particles that are created from vacuum fluctiations have to annihiliate in a very short time, in order to satisfy the energy-time uncertainty relationship. A virtual electron-positron pair lasts something like 10-20 seconds before it disappears. They’re not real particles.”
“But they can become real, right?” She looks a little concerned. “I mean, what about Hawking radiation?”
“Well, yeah, in a sense. The idea is that a virtual pair created near the event horizon of a black hole can have one of its members sucked into the black hole, at which point, the other particle zips off and becomes real. The energy to account for the mass has to come from somewhere, so the black hole loses a tiny bit of mass.”
The tail-wagging picks back up. “Bunnies made of cheese!”
She gives an exasperated sigh. “Look, virtual particles are created all the time, right? Including in our back yard?”
“Yes, that’s right.”
“Including bunnies, yes?”
“Well, technically, it would have to be a bunny-anti-bunny pair…”
“And these bunnies, they could be made of cheese.”
“It’s not very likely, but I suppose in a Max Tegmark sort of ‘everything possible must exist’ kind of universe, then yes, there’s a possibility that a bunny-anti-bunny pair made of cheese (and anti-cheese) might be created in the back yard, but…”
“And if I eat one, the other becomes real.” She’s wagging her tail so hard that her whole rear end is shaking.
“Yeah, but they wouldn’t last very long before they annihiliated…”
“I’m very fast.”
“Given the mass of a bunny, they’d only last 10-34 seconds. If that.”
“In that case, you’d better let me outside. So I can catch the bunnies made of cheese.”
I sigh. “If you wanted to go outside, why didn’t you just say that?”
“What sort of blog post would that be? Anyway, bunnies made of cheese!”
I look out the window again. “I still don’t see any bunnies, but there is a squirrel by the bird feeder.”
“Ooooo! Squirrels!” I open the door, and she goes charging outside, in the wrong direction.
She’s a very silly dog.
Texto tomado del libro
“How to teach physics to your dog” de Chad Orzel