On July 4, 2012, CERN (the European Organization for Nuclear Research) announced a major breakthrough in the search for the Higgs boson. After years of smashing subatomic particles in the LHC (Large Hadron Collider, a $10 billion particle accelerator near Geneva that stretches for 17 miles underground) and no shortage of setbacks, they have finally made headway into what exactly gives particles mass. In a press release, Fabiola Gianotti and Joe Incandela, two spokesmen for CERN, stated that:
“We observe in our data clear signs of a new particle…The results are preliminary but the 5 sigma signal at around 126.5 GeV we’re seeing is dramatic. This is indeed a new particle. We know it must be a boson and it’s the heaviest boson ever found. The implications are very significant and it is precisely for this reason that we must be extremely diligent in all of our studies and cross-checks.”
What does it mean?
This short quote is laced with a lot of science-babble and hard-to understand language. What is a boson? Why is its discovery important? And what is 125 GeV? How can a person without a PhD in particle physics understand the Higgs?
Let’s start at the beginning.
What are we made of?
You, me, a coffee table, even the milky way galaxy can all be broken down into atoms, the fundamental building blocks of matter. Atoms are incredibly small; for instance, if the carbon atoms in a 1cm length of pencil graphite were blown up to the size of peas, they could cover the earth’s surface in a pea carpet 3 meters deep. The video below puts it another way:
Okay, atoms are really tiny, but they’re mostly empty space. So the parts of an atom-the protons, neutrons and electrons-are very very tiny. However, that isn’t the whole story. Protons and neutrons are made up of even smaller stuff, called quarks (of which there are six flavors, like ice cream but called things like ‘up,’ ‘down,’ ‘strange,’ and ‘charm’ quarks) and held together by something called gluons (which are a type of boson). Now, this is only important to the Higgs question in explaining that there are a lot of tiny, tiny subatomic (smaller than the atom) particles in the quantum universe. And all 12 types usually tend to follow the rules of something called the Standard Model.
So what is the standard model?
In particle physics (the field that deals with all of these really small subatomic particles), It is a theory that tries to explain the origins of all of the laws of physics that we experience every day. Think of it this way: if we keep breaking the universe into smaller and smaller pieces, we should eventually find the very things that are responsible for electricity and magnetism, and keep our atoms from breaking apart or going radioactive. This is what physicists have been searching for: the members of the particle zoo that hold the universe together.
However, particles are very hard to find. Some particles only last for a very short period of time. Others need very high energy to come into existence. Still others, like the as-yet undiscovered graviton, a particle assumed to generate the force of gravity, would be incredibly weak in the subatomic scale, even though gravity seems like a powerful force to us. This is where the LHC comes in. By accelerating particles (usually protons) near the speed of light and colliding them, it’s possible to generate enough energy to see these elusive particles.
What about the Higgs Boson?
The standard model was really good at predicting forces and behaviors of different particles; however, it still couldn’t answer the question of what gave things mass (the amount of “stuff” in an object. Black holes are very massive, because they have a lot of stuff in a very small space, whereas electrons have only a tiny bit of mass). For instance, scientists noticed that different particles had different masses, even though they look the same.
Put another way, it’s like having two clear liquids, like water and alcohol, but not knowing why one is heavier than the other. The standard model made the problem even more complicated because it would only work if particles had no mass when the universe began.
Enter Peter Higgs, the man credited with Proposal of the Higg’s boson. Working alongside two other teams, he and his colleagues reasoned that even though particles had no mass when the universe began, a fraction of a second later they interacted with something called the “Higgs Field,” whose force imbued them with their respective masses. In other words, the Higgs Boson is a particle that explains the fundamental force giving things mass.
In even other words, let’s say the particles are all at a party. Some are really famous and others aren’t so much. Let’s also say that there are a lot of paparazzi in the room, clamoring to take pictures of the celebrity particles. Now what if the fire alarm goes off? The particles without paparazzi crowding them can make it to the door really quickly, while the particles surrounded by photographers take a lot longer to reach the exit. The paparazzi can be seen as the Higgs field and make it seem like one type of particle is more massive than another.
How big is the Higgs boson?
Remember that weird unit GeV? It stands for gigaelectron-volts, and is a measure of energy. You know Einstein’s equation E=Mc^2 (energy=mass*speed of light)? Well, if physicists know the energy and the speed of light, it’s simple algebra to find the mass of a particle with that energy. and considering that CERN is still standing behind the discovery of the Higg’s boson, it’s very real mass appears to be around 126.5 GeV/c^2.
Maybe this video can help explain further, courtesy of Jorge Cham and Daniel Whiteson, at phdcomics
**For Middle School and Above