#bosons

Qu’est-ce que la supersymétrie ? Comment peut-on la visualiser ? Quelle est la différence entre les fermions et les bosons ? Toutes ces réponses en 15 minutes !

I love Quantum Mechanics. It’s by far my favourite branch of physics for the very simple reason that it’s fucking bananas. Like, it’s legitimate to interpret the maths in a way that suggests we live in a constantly branching multiverse where every action in which different outcomes are possible leads to the creation of an entirely new universe- the ‘many worlds’ interpretation. But it’s equally legitimate to interpret the maths in a way that suggests a particle occupies every conceivable state simultaneously (though not with equal values of probability) until something happens to cause its wave-function to collapse, at which point only one action is taken within a single universe. So… infinite multiverse or particles existing in multiple places and states simultaneously to accommodate the same range of possibilities. Or some combination of both, since we’re fairly certain that particles exist as probabilistic wave-distributions regardless of whether we live in one universe or many. Like I said: bananas. And the thing is, everything I just said is a wild oversimplification and might be slightly off the mark, because I’m not a physicist. The fun thing is that, even if my depiction of the theory is sketchy and rough, the actual full complexity of reality would be much, much more bananas, not less. Which is awesome.

The thing about Quantum Mechanics is that people tend to give up trying to understand it, especially because all the famous quotes about it relate to how insanely complicated it is and how it doesn’t conform to our intuitive understanding of reality and is, thusly, impossible to picture. Hands up who’s heard the line “If you think you understand quantum mechanics, you don’t understand quantum mechanics”? Well, it’s probably true that a layman like you or I is never going to be able to wrap our heads around the maths, which is what justifies all the bananas-ness of Quantum Mechanics. However, I think the idea that we can’t conceptually grasp it or visualise it is absolute drivelling bunkum that does nothing but contribute to a sense of false mysticism around a fact of our physical reality that we should all make some effort to wrap our heads around. Our concepts and visualisations might compare to reality more like an impressionist painting than a photograph (because, again, we’re not physicists), but for us lay-people that’s probably sufficient. I don’t really have the time or specialised knowledge required to talk you through picturing every aspect of Quantum Theory, but as an interested amateur with a fairly solid conceptual grasp of the ideas, I can give you a reasonable grounding in the basics. To return to the analogy of a moment ago, I can’t show you photographs of the true nature of reality, but I can share my impressionist sketches with you and help you get one step closer to conceptually grasping the quantum universe.

Let’s start at the beginning. The word ‘quantum’ sounds very, very cool, but it just refers to the principle that reality is made of indivisible integer units of fundamental, elementary stuff. Or, to put it another way, subatmomic reality is quantised in whole numbers: you can’t have half an electron or 12% of a Higgs Boson. That’s pretty important, but not immediately so, so just stick in the back of your noggin and we’ll come back to it.

Now, the other major precept of Quantum Mechanics is that particles aren’t solid units of matter in the way that we understand in the macrocosm- I’m not just talking about probability distribution (though we’re getting to that). I’m talking about the fact that most fundamental particles in our reality aren’t really separate from space-time at all, but are actually excitations in fundamental fields that exist at every point in space-time. What is a fundamental field? Well, here’s where I can help you visualise shit! Imagine a flat surface, but give that surface the ability to flow and move and form different patterns. Maybe picture it as a lake of quicksilver, or as a sheen of shimmering colours. It doesn’t really matter- this is an analogy, not a literal representation of what’s happening. Now, imagine that something happens to disturb that flat surface. It forms a spike like a very, very localised wave- as though someone threw a big rock into it. N.B. Nobody threw a big rock- stop picturing the quantum world filled with tiny elves throwing rocks (this note is as much for my benefit as yours- I’m a whimsical man). Anyway, the surface is a fundemanl field and that spike- that deformation of the flat surface- is a particle. Now, this is where things get tricky. Imagine that there are lots and lots of flat surfaces- one for every fundamental particle- all existing at the exact same point, overlapping one another. One surface- one field- is for electrons, while another is for Higgs Bosons and another is for photons, etc. Now, with the mind’s eye, zoom out. This set of flat surfaces is just one point in space-time. You can zoom out infinitely and see that there is an identical set of surfaces for every point in all of space-time. Every excited, deformed surface is a particle, and every flat, tranquil surface is empty space. Boom. If you can picture that, you have a basis for visualising the essential connection between particles and the universe they exist in. You have also grasped, visually, that there is no distinction between matter and energy at this scale, because fields just described are both points in space-time and particles (which make up matter) and the only difference is, well, energy.

Okay, that’s a pretty good way to visualise one aspect of Quantum Mechanics (probably not the best way- get an actual physicist to yell at you about the inaccuracies of this model sometime), but it’s good enough for us muggles. There is, however, two problems with it. First and foremost, it makes the imaginary surface ‘flat’ and therefore two-dimensional in order to make an excitation in that surface easier to picture. Points in space-time are not two-dimensional. Fundamental fields are not flat. But that’s okay. Our first visualisation was just to help you understand how particles exist and what they are. Now that you’ve got the general idea, instead try picturing the fundamental fields as a sort of mist with pretty average distribution. The mists swirl and coagulate suddenly as energy is pumped into them (don’t worry about from where) and become denser and more coherent and suddenly there’s a perfect sphere in the mist, formed from the mist yet distinct from it. This sphere is our three-dimensional version of the spike; it is a particle. Of course, particles aren’t really spheres either- it doesn’t make sense to talk about them as having shape at all, in fact. Nor are fundamental fields mists- they’re more like invisible zones of potentiality. However, the human brain can’t picture something without giving it a shape and colour and it doesn’t hurt anything to picture a particle as a sphere or the field from which it emerged as a mist. In fact, as analogies go, it’s very serviceable. It allows you to visualise a process that doesn’t have a direct analogue in a macroscopic cosmos. So, for the purposes of analogy, the mist is a field that can be excited and that excitation is a spheroid fundamental particle. Congratulations. Your first visualisation allowed you to understand the process and the second has allowed you to make it three-dimensional.

Of course, I said there was two problems with the initial model that we used, and now it’s time to address the second and trickier one. You see, points in space time (whether you imagine them as surfaces or misty areas) aren’t like pixels on a screen, and nor are the particles that emerge from them. They’re not discreet things with definite, defined locations. We have to accept that our nice, neat sphere doesn’t actually have a defined location in space-time connected to a neat point. We talk about ‘points’ in space-time because it makes it easier to picture fields filling each point and allows you to visualise the way excitations in one particular place create particles. But now that you understand that, you’re ready to upgrade your visualisation of the particle itself. You see, the particle is a particle, but it’s also a wave. It exists not as a single, solid mass but as a distribution of probabilities. Did that sentence make sense? No? Okay, let me explain. Imagine that our sphere is actually lots of transparent, insubstantial spheres, moving through one another, overlapping, dividing, collapsing into one another. Some of the moving, spheres appear more substantial than others. And the really trippy thing? They’re all really the same sphere! What you’re looking at, in your mind’s eye, is a particle existing in multiple places and moving at different speeds, all at the same time. It is more likely to be in some spots than the other, which is why some of the sphere-instances are more solid-looking than others. It is less likely to be in other places yet- in a sense- it is there too. This is what is meant by ‘probability distribution’. If the particle is observed or measured- that is, if it interacts with a system that brings it into observable contact with our macrocosmic world- it will cease to act like a wave and cohere at any of the points within its probability distribution, becoming a single, solid ball again in our mind’s eye. This is what scientists mean (well, roughly) when they talk about the ‘collapse of the wave-function’. According to the Copenhagen interpretation of Quantum Mechanics, this essentially ‘deletes’ the non-used possibilities. According to Many Worlds (or some versions thereof), they persist in other universes. The maths works out either way.

Now, every single fundamental particle in existence- from the odd lone ones drifting through the infinite night of space to the very densely-packed ones that make up your own body- are all doing the same thing all the time: existing as fuzzy regions of uncertainty until something collapses their wave-functions. When they interact with one another, they become larger regions of uncertainty that are less fundamental particles, which can interact with one another to become even less fundamental until you eventually get protons and neutrons partnering up with electrons to form atoms, which make up… well, everything in the universe that you’re familiar with. Where the transition happens between ‘buzzing region of quantum uncertainty’ and ‘actual solid thing’…  I have no idea. Somewhere around the large-molecule stage, maybe? Seriously, I told you I wasn’t a physicist. However, I hope that by sharing my own visualisation with you, I’ve helped you picture Quantum Mechanics- or, rather, the very basic building blocks of Quantum Mechanics- just a little better. Doubtless, my visualisations are sketches, not photographs, but they are proof that there is nothing conceptually inaccessible about Quantum Mechanics. All it takes is an imaginative leap.

The Higgs Boson, referred to throughout as the Higgs particle, is one of the fundamental particles of the universe under the Standard model. The Higgs particle is a boson. Bosons are the category of particles that carry the fundamental forces. The other bosons are the photon, W and Z bosons, and the gluon which carry the electromagnetic, weak, and strong forces, respectively. The Higgs particle is so special because it was the last piece of the puzzle and we’ve been looking for it since it was theorized in the 1960s. This is because it’s so difficult to detect.

The Higgs particle is the result of quantum interaction with the Higgs field. The Higgs field is similar to a magnetic field, but it has a constant, non-zero value everywhere. It is interaction with this Higgs field that causes other particles to have mass. However, the Higgs field itself is undetectable. We have theorized it exists, because it had to in order for the W, Z, and gluon bosons to have mass, but we couldn’t measure or detect it directly. That’s where the Higgs particle comes in.

Because the Higgs particle requires so much energy to be created, it doesn’t normally exist. But, because finding it is the only way to prove the Higgs field exists and to “finish” its piece of the Standard Model, scientists set out to create it. At the Large Hadron Collider in CERN, they collided trillions of particles at incredibly high speeds and had supercomputers process the data and spit out anything unusual. It was from these findings in 2013 that two labs concluded that they had created and observed a Higgs particle.

For more information, check out: Simple Wikipedia (don’t let the name fool you, this is anything but trivial and an incredibly valuable resource), Wikipedia, CERN

– Admin Noah