Excerpted with permission from How to Teach Relativity to Your Dog, Chapter 8, "Looking for the Bacon Boson: E = MC2 and Particle Physics," by Chad Orzel. Available from Basic Books, a member of The Perseus Books Group. Copyright © 2012.
Looking for the Bacon Boson: E = MC2 and Particle Physics
Photo Credit: Steve Jacobs
I'M GRADING EXAM PAPERS at the dining room table when Emmy trots in. "Hey, dude," she says. "Where do we keep the superconducting wire?"
I'm not really paying attention, so I start to answer before I understand the question. "Hmm? Wire is in the basement, next to the—wait, what?"
"The superconducting wire. Where do we keep it?"
"We don't have any superconducting wire. And you're a dog. What do you need superconducting wire for, anyway?"
"I'm building a particle collider! I need superconducting wire for the beam-steering magnets."
"Again, you are a dog. Why are you building a superconducting particle accelerator?"
"Well, I've heard all this cool stuff about the Large Hadron Collider (LHC) over in Europe and how they're using it to make all sorts of new particles. And I thought to myself, 'That's a great idea. I should make one of those.' See, my food comes as particles of kibble, and I figure if I slam them together hard enough, I should be able to create whole new flavors of particles!" She's wagging her tail and drooling on the rug.
"Yeah. I might even be able to discover the elusive bacon boson. It's responsible for making other kinds of particles yummy."
"The bacon boson?"
"It's been predicted to exist for years, but it's never been observed by any dog. It'd be the most dramatic discovery in canine physics since . . . since . . . since, like, ever."
"There's no such thing as a bacon boson."
"You're only saying that because nobody has ever observed one. But once I make my Superconducting Kibble Collider, I'll be able to find it, and then I'll be famous."
"OK, look, that's not going to work. Particle accelerators do make new particles by converting kinetic energy into mass, but it takes an incredible amount of energy to do that, way more energy than we can get around here."
"No it doesn't."
"Yes, it does."
"No it doesn't. Look, the peak energy of the proton beams at the LHC now is around 7 trillion electron volts (TeV), which is only, like, 0.00000121J. That's about the kinetic energy of a mosquito. If you dropped a 1g piece of kibble off the kitchen counter, it would have ten thousand times the kinetic energy of a proton in the LHC. And E = mc2, so with that much
energy, we can make all kinds of new particles." She wags her tail, looking smug.
"Falling kibble has way more energy than an accelerated proton, true, but it still doesn't amount to much. Even if you could convert all of that kinetic energy into new mass, you'd only gain about 1.1 . 10-19 kg. That's maybe 10 million atoms worth of extra kibble, which wouldn't change the flavor of anything, even if it was all in the form of bacon bosons—which don't exist."
"But they create way more stuff than that at the LHC, don't they?"
"They do, but to get 7 TeV of kinetic energy into a single proton, it needs to move at 99.99999 percent of the speed of light—which is hard to do with protons, let alone chunks of kibble."
"And even when they do have the proton beams cranked all the way up, they don't manage to convert all that energy into mass every time out. They're lucky to get a tenth of that—maybe one collision in 400 million produces new particles with a mass energy equal to 5 percent of the energy of the collision. You'd need to run through an awful lot of kibble before you got any bacon bosons. If they existed. Which they don't."
"Oh." Her ears droop. "How much kibble would I need?"
"If each piece was 1g, you would need something like . . . twenty thousand of the 40 lb. bags I buy for you. At $30 a bag, that'd be about $600,000."
"And don't say that we could write a grant proposal for that. The National Science Foundation is not going to buy you kibble."
"So, forget about building a kibble accelerator to look for the bacon boson. It's not going to work."
"Let me hear you say it."
"I won't be building a particle accelerator in the backyard to look for the bacon boson."
"Thank you. You're a very good dog." I scratch behind her ears, then resume grading papers.
"I guess I'll have to go with my original plan, then."
"Building a particle accelerator in the backyard to look for the steak quark."
No other branch of physics has managed to capture and hold the general public's interest quite as effectively as particle physics, to the point where most people tend to think that all physicists are particle physicists.* Dozens of popular books and television programs attempt to explain the current state of particle physics to nonphysicists and offer speculative theories about what might come next.
While the emphasis on particle physics can seem a little excessive at times, the field has done a lot to earn its prominent place in the public imagination. The current best theory of fundamental physics, the Standard Model is phenomenally successful, combining quantum physics with special relativity to describe all the known particles in our universe and their interactions. In this chapter, we take a brief look at this "theory of almost everything"** and how it explains the objects we see around us. First, though, we need to look at what it says about the particles we don't see and how we know they're there.
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* Which isn't true—particle physicists account for a bit less than 10 percent of the membership of the American Physical Society. The largest single category of physicists comprises those working in "condensed matter," studying the properties of atoms and electrons in liquid and solid systems such as semiconductors.
** Borrowing the title of Robert Oerter's excellent book on the Standard Model.