So what is this Higgs boson thing all the kids are talking about?
So you know how in high school physics you learned that atoms were made up of the fundamental building blocks of matter: the electron, the neutron, and the proton? That was all a filthy, filthy lie. See, even these particles are made up by even smaller subatomic particles, such as quarks, leptons, fermions, and the lesser known but delicious croutons. Chemists have their precious elements all plotted out nicely in a periodic table, and physicists have tried to copy this model, as seen below:
The fermions (quarks and leptons) can combine to make all the matter we see in the universe. The bosons you see there in the rightmost column give this matter their “forces” (thank you Obi Wan). They carry “forces” like how the photon carries electromagnetism/light, the Z and W bosons carry weak nuclear interaction (a form of radioactive decay), and the gluon carries insults that bounce off me but stick to you. Then you have the Higgs boson, which gives particles mass. Without it you just have particles that take up space (i.e. volume), but have no mass whatsoever. Basically the Higgs boson is the horizontal stripes of subatomic particles. It totally makes the other particles look fat.
Mass is kind of a big deal because without it everything would fly around at the speed of light, which clearly isn’t what happens in the universe. Particle physicists had always theorized about the existence of this Higgs boson–after all, without it their whole explanation of how the universe works via the “Standard Model” (more on that below) falls apart–and they’d seen evidence of all the other bosons except this one. That was, until quite possibly, very recently.
Ok that sounds like a pretty big deal. But how does this Higgs thing work anyway?
The way the whole mass thing works is that there’s actually a “Higgs field” that all matter in the universe flows through. When something flows through it smoothly like, say, a warm knife through butter, it meets little resistance from this “field” and zips right through it. If something goes through this not-so-smoothly like, say, a warm knife through butterscotch candy, there’s more resistance from this “field.” Something that goes through this field with more resistance has more mass, and vice-versa. Differences between condiment spreads and hard candy aside, why does one thing meet more resistance and get more “mass” than another?
The example physicists love to use–possibly because it involves fantasies of parties devoid of social awkwardness–is how crowds gather around a “popular” person at a party. Let’s say some physicist walks in. He’s well-dressed with looks that could kill and charm (of the non-quark variety) that could talk him out of those murder charges. He’s the life of the party, regales people with tales of time travel, and attracts a throng of people to him so much so that it’s virtually impossible to break free of them to get a drink at the bar. Then on the other hand, you have another physicist who walks in. His clothes are shabby and covered with pet hair from his half-alive-half-dead Schroedinger cat. His eyes are bloodshot from staring at a computer screen for 12-hours straight, and despite his attempts at mingling, can’t get anyone to talk to him without excusing themselves to answer a phone call that’s probably fake. He’s free to go back and forth to the bar with ease–which he does, since it’s open bar and the vet says there’s nothing he can do to improve his cat’s condition.
So what does that have to do with the Higgs boson and mass? The people surrounding the popular physician are the Higgs bosons–basically parts of the Higgs “field.” They latch onto him, slowing him down, and in effect, give him more mass. Basically the more popular you are, the more Higgs bosons you gather, and the more mass you get. Or conversely, the more mass you have, the more popular you are. It’s like how they decide the winners of beauty pageants. Except the exact opposite.
What’s with the name of this thing? I’ve heard it referred to as both the “Higgs boson particle” and the “God particle?”
Good question. You see, this subatomic entity was first proposed by the Prussian scientist, Johannes von Particle. He suffered from a rare messianic personality disorder where he thought he could turn a regular street woman into a model of high society–essentially “playing God,” if you will–known as Henry Higgins disorder. This was later shortened to Higgs disorder. Hence the dual names.
Hmm, that’s different from what I’ve read. I thought it was named after the University of Edinburgh physicist Peter Higgs who originally proposed it in a 1964 publication that was rejected.
That is certainly one theory. One that may be more historically accurate and/ or true. Though it should be noted that Prof. Higgs never called it the “God particle” himself. That came from a book by the physicist Leon Lederman who gave it that name and it stuck because it’s a hell of a lot catchier than “Higgs boson.” Interestingly, Lederman claims he settled on that title because his original submissions for the title, “the goddam particle” (since they had been trying unsuccessfully for decades to find it) and the alternative “bigger than Jesus particle” (he was dating a Japanese experimental artist at the time) were both rejected by his publisher. “God particle” stuck though because it’s sort of the “missing link” in the whole Standard Model thing, which in turns explains the entire universe.
So you say they found the Higgs boson? How did they do that?
Actually it’s a pretty sweet gig these particle physicists have. You know how as a kid you would smash things together to see what would happen? That’s what these physicists do at this massive Large Hadron Collider (LHC) in Switzerland. Except instead of smashing matchbox cars into each other or triple-dog-daring the scrawny kid to run head first instead the fat kid, they run two protons through this crazy 17-mile contraption and smash them together traveling near the speed of light.
When these two protons collide they don’t just break into their subatomic parts (a combination of some quarks and leptons and whatnot), they bash into each other and create pure energy the amounts of which exist in parts of the solar system that we’ve never been able to recreate here until we built particle accelerators like the LHC. The idea is that at these really high levels of energy we’ll be able to see evidence of some of these subatomic particles, most of which we have seen, except the elusive Higgs boson.
The tricky thing is you never actually get to “see” the Higgs boson. These bursts of energy last for an absurdly small amount of time–it’s OK though, it happens to a lot of subatomic particles. So you only get to witness what goes into the smashing–2 photons–and what comes out of it after that big energy explosion–two bottom quarks, which is what Higgs boson would almost instantaneously decay into.
Unfortunately it’s not as easy as saying, “Look, we made two bottom quarks! Higgs boson in the house!” The two bottom quarks that stagger away from this wreckage could be created by a number of things aside from the Higgs boson. So these physicists had to run millions and millions of these collisions, chart the amount of energy that was produced from each of the tests, and then compare these results with the results they would expect if these two bottom quarks didn’t come from a decaying Higgs boson.
So they did this many, many times. Smashed a bunch of perfectly good protons together, measured the energy of each of these collisions, and then finally came to an agreement that with 95% certainty (if you want an FAQ on confidence intervals, check this handy link here) they’d found evidence of a Higgs-like particle. They say “Higgs-like” because again, they didn’t actually “see” the particle, and there could be some crazy boson or double-secret-probation-boson that acts just like the Higgs particle but is actually a Higgs boson imposter.
So now that they found the Higgs boson, particle physics is all done, right?
Not by a longshot. There are some people who were kind of hoping they wouldn’t be able to find the Higgs boson because it would mean the Standard Model wouldn’t be right, and they could get cracking on a new model of the universe–possibly through a reality TV show called America’s Next Esoteric Cosmological Model. But even though the Standard Model looks to be holding water, particle physicists are going to have their hands full for the next few years to make sure what they’ve observed is the Higgs boson and not just a Higgs-like boson (some theories say there could be up to five of them). Then they need to go all these crazy tests and probably intrusive probes involving stirrups to make sure it’s interacting with the other particles as the Standard Model predicts. So basically they need to first confirm they did find this elusive shiny new toy, and then they get to test drive it for a while to make sure its not a lemon.
Plus on top of that, there are two other really cool things left to explain. The first is gravity, which is extremely weak compared to all the other forces (e.g. mass, electromagnetism, etc) and–get ready for this–may be because most of it exists in extra hidden dimensions! Hello 8-D movies! The second and much larger issue is that matter (volume + mass) may only account for 4% of the observable universe. The rest could be filled with dark matter, dark energy, and if we’re lucky, some sort of dark chocolate filling. The first two are pretty tricky since as their name would imply, you can’t exactly see them. They’re just hypothesized to make sense of, well, the vast majority of the matter and mass-energy of the universe whose effects we see (e.g. expanding universe) but don’t see the things themselves. So yeah, physicists will need to figure out how to prove the existence of invisible things. That’ll keep them busy for a while.
Gee that sure sounds swell! I’m gonna be a particle physicist when I grow up! Any advice?
Eat your vegetables and stay in school! Also, hurry up and get your PhD in physics ASAP because we’ll probably have robots doing all this work for us in no time.