Ponyville's little red schoolhouse was abuzz with activity as the Cutie Mark Crusaders trotted into their classroom. Snips and Snails were arguing about who was the coolest character their favorite show for little colts, Pipsqueak was running around playing a rambunctious game of tag with Featherweight, and Silver Spoon and Diamond Tiara were whispering just loudly enough for others to hear their condescending remarks. The cacophonous noise was instantly muted when Cheerilee stepped into the room, and all the little ponies zipped into their seats.
"GOOD MORNING, MS. CHEERILEE!"
"Good morning, class. We have a bit of a schedule change for today. I'm going to postpone our lesson on General Relativity to talk about a very exciting new discovery in Particle Physics. Has anypony here heard of the 'Higgs boson'?"
Apple Bloom's hoof shot up. "I heard Twilight Sparkle talking about it with my sister. It's a new particle that lots of scientist ponies are really excited about!"
"That's right. So I'm going to give a lesson to teach you all about what the Higgs boson is and why it's such an important finding. First off, do you all remember when we learned about the Standard Model of particle physics?"
Everypony nodded.
"Good. So who can explain what the model tells us about our world?"
The class was quiet for a bit, but Scootaloo cautiously raised her hoof. "It explains how the teeny tiniest kind of stuff works."
"Good job, that's a very nice way to put it! Now let's list some of those teeny tiny things." Cheerliee picked up some chalk with her teeth. "Who can give me the thix flavorth of quarkth?"
"Up, down, top, bottom, charm, strange!" called out Pipsqueak.
"Thath right!" said Cheerliee as she wrote them on the blackboard. "What are their colorth?"
"Red, green, and blue!"
"Right! Howth color change affect quarkth?"
"Ummm...."
"Thombody help him out."
"It makes them stick together," said Featherweight.
"How?"
"The strong nuclear force."
"Which ith carried by the..."
"...the gluon?"
"Right." Cheerliee took the chalk out of her mouth. "The Standard Model describes how particles interact with each other by exchanging force carrier particles. For instance, two up quarks and a down quark make up every proton in every atom in the galaxy. As the quarks constantly change color, the exchange of gluons will ensure there's always one quark of each color: red, green, and blue. This exchange binds the quarks together and ensures those quarks will stay together forever. All of the quarks in your body have been bound in together in color-changing triplets since the Big Bang over 13 billion years ago."
"Let's get a bit more organized." Putting the chalk back in her mouth, Cheerilee wrote "Matter" above the list of quarks, "Force Carrier" above "gluon", and "Forces" above "strong nuclear."
"Leth fill in the chart. What elth makth up matter?"
The class was completely silent.
"Come on, what elth ith in an atom?"
Sweetie Belle decided to be brave. "Neutrons and electrons?"
"Good. Which of them are elementary particleth?"
"Electrons?"
"Right. I'll give you the other two: 'muon' and 'tao'. Together, the three are the charged leptonth. What are the uncharged leptonth?"
"Oh yeah, the neutrinos! One for each kind of charged lepton."
"Good. We'll forget the antipartileth for now. What other forceth do we need?"
"Weak nuclear force, electromagnetic force, and gravity."
Cheerilee took the chalk out of her mouth once she finished writing. "I'm going to put a box around 'gravity' because it actually can't be explained with the Standard Model. Scientists speculate we may one day find a 'gravitron' and come up with a grand 'Theory of Everything', but we aren't there yet."
"Luckily, for the weak nuclear and electromagnetic, we've found the force carriers. Electromagnetic force is conveyed by Princess Celestia's favorite particle."
Sweetie Belle smiled. "Photons."
"Yes! And do you want to earn a special smiley star for today by giving me the weak nuclear force carriers?"
"The ones with letter names... the W and Z bosons?"
"Excellent!" Cheerilee finished off the chart and turned back to the class. "When we studied these particles, we learned about their intrinsic charge and spin. Each particle also has its own mass, but that isn't an intrinsic property. For the Standard Model to be true, the particles need to get their mass from another particle. With the exception of gluons and photons, there was no way to explain why some particles were more massive than others. That is until we got... the Higgs boson! The particle that completes the Standard Model!"
Cheerilee's enthusiasm was greeted by blank stares, but she was undeterred. "We've been sitting down too long. Who wants to be a proton that gets spun around in a particle accelerator?"
More blank stares.
"You get to wear these helmets and crash head first into each other."
Snips and Snails jumped out of their seats and Cheerilee got them set up for the demonstration. "Elementary particles are far too small for us to see directly. We detect them by sifting through the wreckage of particles that get smashed together. Snips, please give us a gentle trot going clockwise around the room; Snails, you can go counterclockwise." The ponies picked up speed as Cheerilee continued. "You all remember that E=mc^2, right? That equation means that energy can get converted to matter and vice versa. You're about to see that happen here: 3, 2, 1, smash!"
Snips and Snails met in a thunderous collision but came out of it laughing and relatively unhurt. "Thank you for your help, boys," said Cheerilee. "Please return to your seats."
"This is how we created enough energy to make particles like the Higgs Boson. Many particles are created in such a collision, and we can sift away the ones we already recognize to find one that's new. That's how scientist ponies detected the Higgs boson."
"But that's just a special laboratory setting. I need some more volunteers to demonstrate how the Higgs behaves everywhere else in the universe." Everypony wanted to volunteer this time, so Cheerilee said, "Let's have Pipsqueak and Featherweight be two particles of different mass. Everypony else can be a Higgs boson!"
That got everypony up and excited, but Cheerilee got them all corralled into an orderly group. "Let's start by reminding ourselves about how we can see the effects of mass. Everypony please push your desk to back of the room."
Once everyone had complied, Cheerilee said, "Now could someone come up here to push my desk?" Apple Bloom volunteered, and she managed to move the desk with the help of her applebucking legs.
"Good work! So Apple Bloom, why do you think it took more work to move my desk?"
"More mass?"
"Right, and we're ready to see how Higgs Boson can make it harder for massive particles to move."
"One of the most amazing things about the Higgs bosons is that they're absolutely everywhere. We can think of the universe as a great big party and the Higgs bosons are all the guests. Massive particles are like very friendly party-goers, and they want to stop and say 'hi' and chat with everyone they meet. Low mass particles are less friendly spend less time chatting. Everypony can start milling around the room now, and I'll get our two particles ready to meet you."
Once Cheerilee told him what to do, Featherweight made it across the room fairly quickly; he said 'hi' to each pony, but he didn't stop to chat. Pipsqueak moved a lot slower because he had to give a compliment to each pony he met before moving on. Despite this, he was grinning from ear to ear by the time he reached to other side of the room; he'd always been a bit shy, and this was a fun way to be outgoing for once.
"Good job everypony!" said Cheerilee. "Let's put our desks back in order and sit down." Once this one done, she said, "It's almost time for our morning snack and recess, so I hope you all have a bit more understanding of the Higgs boson and how our universe works. Are there any questions?"
Diamond Tiara raised her hoof. "Why do we have to learn this?"
"Good question. I try to give my students a very broad range of understanding about things they can study when they grow up. Finding a scientific discipline you like is kind of like finding a cutie mark; it helps to try out as much as you can."
"Well I already have my cutie mark, and I won't ever have any use for knowing about Higgs bosons."
"That may be true, but everypony's life can be enriched by learning more about the world we live in. It might seem strange and complicated, but it's scientific fact."
Diamond Tiara opened her mouth again, but a sharp look from Cheerilee made her close it. "Finally, there's one more reason why we should all try to learn about the Higgs boson: it was discovered through the magic of friendship. Over 10,000 scientists from over 100 countries all worked together to make this historic discovery. It's one of the largest and most elaborate experiments ever conducted, and it was successfully completed because enough ponies were willing to devote good chunk of their lives to it. Even if you aren't interested in the Higgs boson, you have to admire the ponies who discovered it and appreciate an accomplishment that all of ponykind can be proud of."
The bell rang, and all the little ponies rushed outside. The Cutie Mark Crusaders were all bursting with energy. "Congrats on your smiley star!" said Scootaloo.
"Thanks," said Sweetie Belle, "I really liked what Ms. Cheerilee said about how learning lots of stuff can help you find your cutie mark."
"Me too," said Apple Bloom, "After school we can build our own particle accelerator and be..."
All three fillies took up the cry: "CUTIE MARK CRUSADERS: PARTICLE PHYSICISTS!"
