I was browsing a few articles, catching up on one of my other interests – physics – when I found something about a story I’ve been following for several years; the search for the Higgs Boson. Wikipedia describes it thus: “…[T]he Higgs boson is the quantum of one of the components of a Higgs field. In empty space, the Higgs field acquires a non-zero value (or non-zero vacuum expectation value), which permeates every place in the universe at all times.”
Very Nice. Come Again?
OK, for those of you with a physics-tuned mind can switch off; this is going to be layman’s only, and any errors are mine, either through poor translation or a lack of deep understanding of quantum theory.
In Physics, there exists a concept called the “Standard Model” – basically a conceptual outline of how quantum-level effects give rise to all structures in the Universe. Of particular note in the Standard Model are two main concepts; Particles and Fields.
Particles are the stuff that makes up the universe.. simple, really; your electrons, your protons, your quarks… basic stuff, except where it gets exotic, like muons, W and Z bosons and so on… I won’t go into them here, but they get complicated.
Fields are effects in the universe; your electromagnetic field,for example, is the effect of electromagnetism on objects, space-time and, indeed, other fields. Now it gets juicy when you see that in the Standard Model, fields are transmitted via other particles. So, for example, the electromagnetic field is carried and effected by the photon.
Field-carrying particles are called baryons; they are a small family, consisting of the aforementioned photon, the gluon, and the W and Z bosons. As far as the Standard Model is concerned, all fields in the universe utilize these particles.
How Fields “Work”
A basic conceptual overview of fields can be provided by this incredibly simplified example. Two electrons are approaching each other. They both carry an equal negative charge, so, in keeping with your high-school physics, they repel each other. At a highly-granular level, we see that they are surrounded by an electromagnetic field, which is expressed as a “cloud” of photons. These photons don’t actually exist in the physical sense, at least not yet, but their effect exists as a field.
As the electrons approach one another, the energy concentration around them increases, as a result of the increased density of the electromagnetic field. It’s rather like having two “blobs” of mist approach one another; the density of the mist increases as they approach and finally combine.
This extra energy has to go somewhere; the easiest way that the universe deals with energy excess is to pipe it into the creation of new particles; eventually, the energy reaches a critical point where the field is dense enough to actually express itself as a particle.
This may seem “weird”, but remember that Einstein demonstrated that matter and energy are the same thing; indeed, particle “mass” is expressed as an energy quotient (the electron Volt, or eV - but more on that later). It’s not surprising, therefore, that with increased energy, particles that correspond to that energy can be “created”. (This is not true “creation” in any sense; merely a transfer of energy into matter.)
Anyway, back to our electrons. When the density of the field reaches this critical point, a photon is emitted; this strikes the other electron, imparting its energy to that particle. This has the effect of jostling the electron out of it’s initial course, and onto a new one, so that the two electrons move away from each other. From a macroscopic viewpoint, the electrons have just repelled one another.
So What Does The Higgs Particle Do?
The Standard Model has a little problem; as far as our understanding of it goes, there is nothing that “tells” a particle exactly what it is; why is a photon a photon, a neutron a neutron, and so forth? If mass and energy are equivalent, why do certain particles always get produced, even if the energy available is sufficient for them to produce some combination of other particles? If, for example, the field densities were enormous, why do interacting electromagnetic fields always express themselves as photons? The answer is the Higgs Field.
Essentially, the Higgs Boson, and by extension, the Higgs Field, operates to “mop up” the energies of interactions and collisions, reducing the number of overall configurations that particles can achieve in their interaction with one another. This acts as a brake on the process, streamlining particle-particle (and particle-field and field-field) interactions so that they do not “cascade” in sufficiently energetic situations. Basically, any “freak” particles that might be expressed in any given interaction, are subjected to the Higgs Field, their energy is sapped and they drop down to produce the “normal” particles. Of course it’s a lot more complex than that in the real world, but I’m trying to give a layman’s view here.
So Why Haven’t We Found It Yet?
Well, there are two problems; firstly, the Higgs Boson is pretty big. As mentioned earlier, mass and energy are the same thing; in order to “spot” a particle, physicists have to give a reaction sufficient energy to separate it from the background. The electron Volt can be defined as the amount of energy given to an electron by passing through an electromagnetic field of one Volt; the Higgs Boson has to be of a mass greater than 114.4 GeV (Giga-electron-Volts – or 1,000,000,000 eV!) since that is about as high a field as we can produce right now.
Secondly, the Higgs Boson is inherently unstable; hardly surprising when you consider its role is to appear and then break down almost instantly when it’s job of giving other particles their “identity” is done. This gives us a tiny window in which to spot it.
There are some tantalizing glances; this article suggests that it may have been spotted, but it’s not quite clearly defined enough to say for certain. Other experiments give us a top value of about 144 GeV for its mass – basically, if it was any “heavier”, it would not be able to operate as it is thought to.
Why Should We Care?
Well, it’s not going to change your life if the Higgs Boson is found. Life will not suddenly become perfect, the world will not become unified with angelic choruses singing “hallelujahs” to the skies… but it will vindicate the Standard Model. Yes, there are alternatives to the Higgs Boson, but they tend to be, in computer parlance, a little “kludgy”, and the one thing we’ve learned from physics is that it’s pretty elegant.
Besides, I like knowing things like this; they’re unimportant in one sense, but they demonstrate very clearly just how far we’ve come as a species. Just a few thousand years ago, we were standing on the plains at night, fearing the stars, and now we are peeling the lid off and rooting around inside the very universe itself, finding answers that frankly boggle the mind.
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