Scientists at CERN have announced that it's quite likely they've finally cornered the primary quarry of their latest and biggest machine, the Large Hadron Collider. I'd like to call it the Higgs, but others will insist on calling it "The God Particle."
If you remember nothing else from this article, I'd like you to remember this: please don't call it The God Particle. According to Rutgers University physics professor Matt Strassler, who knows a lot more about this stuff than I do, "The origin of the nickname is about as non-religious and non-scientific as one could imagine: it was invented as advertising... I have never heard or seen a physicist refer to the Higgs particle in this way in the context of a scientific paper, a talk at a conference, or even an informal scientific discussion. There’s nothing in the mathematical equations, in the interpretation of the physics, in any philosophy of which I am aware, or in any religious text or tradition with which I am familiar that connects the Higgs particle or the Higgs field with any notion of religion or divinity. The nickname is pure invention."
Now that that's out of the way, what is the Higgs? To answer that question, we need to go back in time to 1932 and a discovery of something called the neutron. Scientists already knew about protons and electrons, two of the basic building blocks of matter. Electrons and protons both have something called electric charge. You can get an electric charge by touching the Electrostatic Generator at COSI, or by rubbing your socks across the carpet on a dry day.
The neutron was a third building block of matter, but with no (or neutral) electric charge. That neutral charge gave the neutron its name.
The weirdest thing about the neutron, though was that it was unstable. Put a billion neutrons in a box, and in around fifteen minutes half of them will have decayed into a proton, an electron, and another particle called a neutrino (I wrote about neutrinos a little while ago here.) It took around thirty years for scientists to really understand what was happening when a neutron broke down this way. When they finally understood it, scientists received a shock. When looked at in the right way, the breakdown of the neutron looked a lot like the interactions between electrically charged particles.
The breakdown of the neutron and other similar events had been named the weak interaction, for reasons we don't have to worry about here. When scientists realized that the weak interaction looked a lot like the electric interaction they already understood, they renamed the whole works the "electroweak interaction." Those scientists and their clever names!
Anyway, though they look a lot alike up close, from our vantage point electricity and the weak interaction look very different. Why?
Imagine you are a fish living in a very strange ocean. This ocean has no surface, no floor, no islands or continents or anything at all to break it up. It is nothing but water as far as the fins can stretch. All you've ever experienced is this ocean all around you all the time.
This is exactly the situation scientists say we are in. In the 1960s a large number of scientists (including one named - wait for it - Higgs!) proposed that we are living in an ocean of sorts, an ocean they call the Higgs field.
To go back to our fish analogy, how would you ever learn that you're living in water? Well, one way would be to do experiments. Maybe this water affects some objects more or less than others. Maybe some objects feel the stickiness of water more than other objects.
Remember our neutron? Higgs and others proposed that the reason the neutron's weak interaction looks so different from ordinary electricity is that the pieces that make the weak interaction happen called the "W" (for weak, get it?) and the Z (for - OK, I don't know what that's for. I guess they were running out of letters), "stick" to the Higgs field. This stickiness we see as heaviness. And because these particles are heavy, the weak interaction behaves differently from electricity.
But wait, there's more. Scientists realized that not only the W and Z's would be sticky in the Higgs field. Almost every other particle, including protons, electrons, and neutrons would be sticky, too. The reason any of us weigh anything, it turns out, is because the stuff we're made of feels this invisible ocean all the time!
This may sound crazy, but here's the thing: Scientists predicted the W and Z particles must exist. Then they went looking for them, in just the way theory said they ought to be found. What happened? The W's and Z's were really there! Doing so well with the W's and Z's gave scientists confidence that they were on to something, and so they starting looking for the Higgs, a much harder thing to find. In fact, it's been nearly fifty years since ideas about the Higgs first formed. Finally, scientists were able to build the right tools to find the Higgs, and lo and behold, there it was!
It's an amazing time for physics. The discovery of the Higgs after all these years may well mean we're on the verge of new breakthroughs that we never dreamed of. Only time can tell what the scientists will discover next.
I said scientists wanted to find the Higgs field. Yet you've probably been reading about the Higgs particle instead. What gives?
The particle is just one property of a field. Think of it as a bump in the Higgs field, that lets us learn about the field's properties. It's the field the scientists are after, not so much the particle.
Finding the Higgs required some of the most complex machinery ever built on this planet, but believe it or not the basic idea can be found in an exhibit at COSI!
In our Gadgets area we have an exhibit called "Crazy TV." In the olden days when 'Skype' would get you a red squiggly line from your spell checker, televisions were huge, clunky things as deep as they were wide. This was to make room for the picture tube.
Picture tubes are really electron guns. Electrons come flying out of the back of the tube and hit the screen, making a flash of light. Enough flashes in just the right place, and you've got "I Love Lucy." At COSI, guests use a magnet to change the place electrons hit the screen. Magnets make electrons change their path, just like a stiff wind might blow you off a sidewalk. When the electrons hit an unexpected place on the screen, the picture there goes crazy.
In the Large Hadron Collider, scientists do the same thing. Instead of electrons, though, they fire protons (that other building block of matter). And instead of just one gun, scientists use two, so that protons fly toward one another. Giant electromagnets bend the paths of the protons into a circle, until every once in a while they collide head-on. A few of those collisions are just right to make a "bump" in the Higgs field. That bump is the Higgs particle!
Science is a long and beautifully connected story of discovery after discovery, each one revealing a bit more of this amazing universe. Congratulations go out to all those scientists who've given us another precious bit called the Higgs. What can we discover next?
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