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  • The Higgs Boson Part I: What it is and why it matters

  • Let's cut to the chase: as of July 4, 2012, the Higgs Boson is the last fundamental piece

  • of the Standard Model of Particle Physics to be discovered experimentally. "But," you

  • might ask, "why was the Higgs Boson included in the Standard Model alongside well-known

  • particles like electrons and photons and quarks if it hadn't been discovered back then in

  • the 1970s?" Good question. There are two main reasons:

  • First, just like the electron is an excitation in the electron field, the Higgs boson is

  • simply a particle which is an excitation of the everywhere-permeating Higgs field. The

  • Higgs field, in turn, plays an integral role in our model for radioactive decay, called

  • the weak nuclear force (in particular, the Higgs field helps explain why it's so weak).

  • We'll talk more about this in a later video, but even though weak nuclear theory was confirmed

  • in the 1980s, in the equations the Higgs field is so inextricably jumbled with the weak force

  • that until now we've been unable to confirm its actual and independent existence.

  • The second reason to include the Higgs in the standard model is some jargony business

  • about the Higgs field giving all other particles mass. But why does stuff need to be "given"

  • mass in the first place? Isn't mass just an intrinsic property of matter, like electric

  • charge? Well, in particle physicsno. Remember that in the Standard Model, we first write

  • down a mathematical "ingredients list" of all the particles that we think are in nature

  • (and their properties). You can watch my "theory of everything" video for a quick refresher.

  • We then run this list through a big fancy mathematical machine, which spits out equations

  • that tell us how these particles behave.

  • Except, if we try to include mass as a property for the particles on our ingredients list,

  • the math-machine breaks. Maybe mass was a poor choicebut most particles we observe

  • in nature do have mass, so we have to figure out some clever way of using ingredients that

  • will spit out mass in the final equations without it being an input - kind of like how

  • you can let yeast, sugar and water ferment into alcohol that wasn't there to begin with.

  • And as you may be thirstily anticipating, the solution is to toss a yeasty Higgs field

  • in with the other ingredients of the Standard Model, so that when we let the math ferment,

  • we get out particles that have mass! But this model also brews up something we DIDN'T intend:

  • a solitary Higgs particle, the infamous boson. And since the model works so well to explain

  • everything else, we figured it was pretty likely that the lonely boson is right, too!

  • To summarize, the Higgs Boson is a particle which is a left-over excitation of the Higgs

  • field, which in turn was needed in the Standard Model to 1) explain the weak nuclear force

  • and 2) explain why any of the other particles have mass at all. However, the boson is the

  • only bit of the Higgs field which is independently verifiable, precisely because the other bits

  • are tangled up in the weak nuclear force and in giving particles mass. The fact that the

  • Higgs Boson is so independent from the rest of the Standard Model is why it's the last

  • piece of the puzzle to be discovered - and if it turns out to be exactly what was predicted,

  • the Standard model will be complete.

  • The only problem is that we know that the standard model ISN'T a complete description

  • of the universe (it entirely misses out on gravity, for example). So to physicists, it

  • would be much more interesting AND helpful if the Higgs boson turns out to be not quite

  • what we expectthen we might get a clue as to how to reach a deeper understanding

  • of the universe. So even though we just made a discovery, we can't sit back and relax.

  • We need a hint, Mr. Higgs.

  • Continued in Parts II and III

The Higgs Boson Part I: What it is and why it matters

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The Higgs Boson, Part I

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    Why Why posted on 2013/03/29
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