Higgs Boson

By | 2012-07-04

The Higgs Boson, eh? Buggered if I know what’s going on.

My grasp of physics is, while not post-graduate level, better than the average citizen. When it comes to quantum, my brain just hurts. I don’t feel any shame at that. Richard Feynman told us why:

I think I can safely say that nobody understands quantum mechanics.

and

If you think you understand quantum mechanics, you don’t understand quantum mechanics

Fortunately, I don’t think I understand quantum mechanics. I’m not sure whether that, by Feynman’s rule, means that I do or not though1. Still I feel I should try and pull some sense out of all this talk about the Higgs Boson.

Firstly, let’s forget the idea that it’s a “God Particle”. It says nothing about God. Religion is for the religious; let’s leave it to them.

The Higgs Boson is

an elementary particle in the standard model of particle physics.

However, it’s probably not a particle either (in the sense that we mortals would understand the word “particle”). It’s just that that’s the best name we’ve got for describing these very small things.

A bit of history then. At first we had natural elements: earth, fire, water, air. We thought that everything was made of some particular ratio of these elements. While the conclusion was wrong; the reasoning wasn’t bad: everything is made of something else. Then we had molecules; we were very pleased with them, “stuff” is all built from molecules (if you’ll allow me the slight transgression of treating single atoms as a molecule too). Next came the bits that molecules were made from, atoms. Atoms are so named because it’s Greek for “indivisible”. For a long time they were just that.

Then a clever chap called Rutherford conducted an experiment that revealed that almost all the mass of an atom is held in a dense nucleus at its centre, with negatively charged, lightweight particles (electrons) orbiting it.

Different stuff gets its different properties depending on what atoms it is constructed from. Each atom is a nucleus of one of the chemical elements, orbited by a number of electrons.

The nucleus itself turned out to be made of two more fundamental building blocks: protons and neutrons. An understanding of neutrons, protons and electrons covers pretty much all chemistry and is about as much as you need to know to understand 99% of what “stuff” is. Alpha radiation is a stream of big heavy neutrons; beta radiation is a stream of light weight, but higher energy electrons (gamma radiation is something else). Your GCSE education will have stopped here. As it should.

Then we started using alpha and beta radioactive sources, combined with some strong electric fields to start blasting apart nuclei. Darn it if the neutrons and protons didn’t turn out not to be fundamental after all; smack them hard enough and they break apart. Out came a whole new mess of stuff. That mess of stuff is what is covered by the standard model. It’s assumed that this really is the end, that there is nothing more fundamental than these particles. These truly are the “elements”, unfortunately, that name was taken, so they’re called the “elementary particles”.

Broadly, there are three groups of particle in the standard model:

  • The Fermions (divided into quarks and leptons). These obey the Pauli exclusion principle (whatever that is), and are pretty much the things that make up what we think of as “matter” on a large scale.
  • The Bosons (photons, gluons, gauge bosons, the Higgs Boson, and the graviton). These don’t obey the Pauli exclusion principle and can occupy the same place in space. This makes them the force carriers. The forces that come from electric fields, magnetic fields, light beams, and the forces that hold the atomic nucleus together, and (if theory is correct) the force that makes one bit of matter attract every other bit of matter… gravity.

Already then, we’re well on our way. The fermions are what make “stuff” we can touch; and the bosons are what makes some stuff attract or repel other stuff.

With one significant exception, almost all forces we experience on a macro scale are electromagnetic (gravity being the significant exception). When I pull on a door handle, I’m stuck to the ground with gravity, but the force generated by my muscles is chemical and hence electrical. It is electric fields that cause molecules to stick together, and electric fields that stop your arm from passing through walls (remember, atoms are mostly empty space, so if there were no electric field stopping you, you would simply pass through all other matter, mostly unhindered).

The photon is the electromagnetic field force-carrier, mesons carry the nuclear force, and gluons carry the strong force that binds quarks into neutrons and protons.

Gulp; here we go… The Higgs Boson is the carrier for the Higgs field. (This is where I lose it). Depending on how you look at it, we have no macro-level experience of the Higgs field at all or it is so fundamentally present that we can’t envisage it as a field. The Higgs field is assumed to exist throughout all of space, by connecting to this field a particle acquires a potential energy (in the same way that a boulder at the top of a hill has potential energy), by Einstein’s finding of mass-energy equivalence, that energy takes the form of what we know as mass. We experience the force of the Higgs field in the form of inertia — the unwillingness of mass to change velocity. It’s easy to confuse this with the force of gravity, which is related to mass but isn’t explained by the Higgs field.

Finding the Higgs Boson will offer a lot of credibility to this theory. It will be found by accelerating other particles up to energies high enough to break a Higgs particle off when they collide. These are energies only previously seen during the first few nanoseconds of the universe’s existence.

It’s unfortunate that such a big deal is being made about the Higgs particle, because while it will be nice to confirm the predictions made by the standard model it doesn’t tell us a lot about what “mass” actually is, or about this strange Higgs fields that permeates the universe. This is the nature of fundamental research though: you never know what you’re going to find until you look. Who knows? We might find a way of tapping into the potential energy of the Higgs field and getting free burgers for life.


  1. I don’t

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