The Higgs

A friend asked me to explain the implications of the current Higgs hoo-ha in a tweet. I failed. This was the shortest I could manage! Let me know if any of it is too terse…

The Higgs boson is the only particle in the ‘standard model’ of particle physics which we aren’t 100% certain exists. There are two types of particle in the model: fermions, which are ‘stuff’ (eg electrons, and the quarks which make up protons and neutrons); and bosons, which transmit forces (eg photons, which are particles of light, and transmit electromagnetic forces). The Higgs boson is one of the latter and, if it exists, would be responsible for giving particles mass. The theory says that the Universe is filled with a sticky soup of Higgs particles, and those particles which interact most strongly with these Higgses are bogged down by them. This is what we think of as mass—a tiny, light electron barely sees the Higgs particles, whilst a quark (the tiny particles which make up, amongst other things, protons and neutrons) is wading through a dense sea of them.

Physicists spot new particles by looking for their decay products. They carefully catalogue the showers of daughter particles which follow a collision in the LHC, and effectively draw dotted lines back to look at where they came from. They then see how many particles came from one specific point, and add up their masses to find the mass of the particle which was originally there. What the guys and gals at CERN are seeing is a large, discovery-quality excess of points where a specific mass seems to be. This might be the Higgs. In order to be sure it’s the kind of particle we’d call the Higgs, rather than just a totally left-field discovery, we need to do more detailed analysis of the kinds of particles it decays into, and how often it decays into each. If this matches the signature of the Higgs, that’s almost certainly what we’ve got—and in fact, given where we’ve been looking in order to find it at all, this already looks fairly likely.

If this new particle is definitely the Higgs boson, it would be the last piece in the standard model’s mathematical house of cards, and we’d have a very large section of the Universe tied down with theory. However, it’s not the end of physics: the standard model explains very well how small numbers of fundamental particles interact, but it can’t describe how huge collections of particles work together (from solids and liquids to the Earth’s atmosphere); gravity (which is rather important!); or, even in particle physics, the weirdest, tiniest fermions we know of called ‘neutrinos’.

Comments

  1. That is surely short enough to fit into a news report instead of all this jargon (the BBC apparently expects people to know what an “inverse femtobarn” is) and rubbish about the “god particle”.

    Thanks, Andrew.

  2. very nice – one suggestion: a few sentences to the effect of “which means we will now be able achieve X,Y & Z and build a fully functioning replicator/wormhole/risk-free derivative instrument”

  3. Well, I’d love to…but I’m afraid I can’t think of any! The practical applications of particle physics at the moment seem to be very much focussed on the spin-offs: massive superconducting magnets from the particle accelerators which can be used in nuclear fusion reactors, expertise in developing insane computing hardware to store and process all the data produced, etc.

    The W and Z bosons, similar particles discovered at CERN in the 80s have found, as far as I know, no direct practical application. Any particle physicists care to correct me on either count?

    I think we’re just doing this for the love of fundamental discovery—but there’s always the unknowable chance something mad and useful may be lurking in left field.

  4. Well, if you think about it, we predicted and found positrons & now use them in PET scanners. We wouldn’t be able to do to that unless we understood what antimatter was and how it is formed. In fact, there are still a lot of questions about antimatter that we haven’t answered… but at least we know it exists and how to make it..
    I’m not saying that we’ll be able to directly use the Higgs itself, but having a fundamental understanding of how particles acquire a mass could lead to applications we haven’t even dreamed of yet. I think that’s the most exciting part…
    If I just said “yeah, if we find the Higgs we’ll be able to make an even better teapot than we do now” I think particle physics would be selling itself short!

    (Just for the record, I have no idea how you’d make a better teapot with knowledge about the Higgs…)

  5. Curious: after dozens of journalist articles and rubish about the “god particle” I finally get into the scientific meaning of Higgs in just 350 well written words.
    Well done Andrew!

  6. Nice one! Expect to see this, or something very similar, on the BBC website soon, ha.

    One practical application will presumably be in weight loss medication.

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