Sunday, July 08, 2012

Higgs boson Special

For anyone who is into physics, this has been such a big week that I *have* to write a special! On Wednesday, July 4, physicists at CERN announced that they had found a new fundamental particle, the heaviest of its kind. But what the Higgs boson is all the fuss about? A couple of you have asked why this announcement is so important. Here’s my attempt at pulling this all together.

Ah, but before I begin I need to prattle on about something almost equally momentous … Wimbledon! I never thought I’d say this, but I’m voluntarily watching ESPN for the Wimbledon Gentlemen’s Final: Andrew Murray (UK) versus that other chap (I’m not biased). Britons love their sports as much as any nation. I think the top 7 would be tennis (my favourite), football (known as soccer to confused people who think that holding the ball with their hands is football), cricket, horse racing, golf, snooker, darts, and, of course, tiddlywinks. The last time a British man won a singles title at Wimbledon was 1936 (Fred Perry). The last time a British man even played in the singles final was 1938 (Henry Austin). This was before the second World War!! Yesterday was a great day too… the Men’s Doubles Finals had a British person, Jonathon Marray, as part of the winning team (his partner was from Denmark, Frederik Nielsen). The first time since 1936!  Regardless of the outcome friends, this is history.

<Major Science Alert>

Back to science.

First, you need to know a bit about atoms. Everything is made of atoms. Atoms consist of a nice gooey center, called a nucleus, and a lovely crunchy coating of particles that zip around the center called electrons. The nucleus consists of two particles: the proton and the neutron. In turn, protons and neutrons are made of even smaller subatomic particles called quarks. Quarks are one of the three absolute basic particles we know about. The other two are called leptons and bosons. Leptons are the particles that give electrons their mass. Everything we see has a mass, thanks to your friendly little quarks and leptons. Bosons are slightly different. They are not mass, but are associated with force. Quarks, leptons and bosons work together, but interact differently which is why some things are heavier than others (eating too much cake and ice cream just means one accumulates more quarks, leptons and bosons of a particular configuration ;-)).

Now you know about atoms, the next thing you need to know about is force. There are four basic interactions (fundamental forces) that explain *everything* we know about, from atoms to people to tropical storms to galaxies:

1.There is gravity which is pretty well known. This is why a tennis ball falls to the ground if you throw it up into the air.

2. There is the electromagnetic force. An electric field can be created when charged particles (electrons) are in a moving magnetic field. The earth is one big magnet, so we live in a magnetic field. The atoms that make us have electrons. As Andy Murray runs around Center Court, he is creating a weak electric field. Conversely, an electric current, which is a flow of charged particles, creates a magnetic field. This is known as electromagnetic induction, and is used to create electrical generators, transformers etc. that are used in all aspects of our electronic lives, such as the TV and satellites that allow me to watch Wimbledon or the computer that allows me to tell you that I’m watching Wimbledon. Both electric and magnetic fields are two sides of the electromagnetism coin. (Taking a break to watch Murray take the first set, and YES! that’s in the bag. J).

3. There is the weak interaction (weak nuclear force). This is responsible for radioactive decay, fusion and all that jazz. It is what makes stars generate energy through a process called nuclear (hydrogen) fusion. Our Sun is a star which is bestowing it’s golden rays on Center Court in London right now.  

4. There is the strong interaction (strong nuclear force). This is actually a much stronger force than the others by a long shot! It is what creates the nucleus of an atom by binding together the protons and neutrons. You need a humongously massively huge amount of energy if you want to separate the protons and neutrons in an atom.

There are no other forces, just these four. All the others that you have heard about are some rendition of these four. The other interesting tidbit is that quarks are the only elementary particles that are directly influenced by ALL four of these fundamental forces. (Drat, Federer just won the second set).  

The theory that has managed to explain almost everything we observe about these forces and particles is called the Standard Model. There are a few things that it doesn’t yet explain, like dark matter. (Rain delay at Wimbledon! Watching this is making me hungry… time for nutella on toast. What do you mean it’s lunchtime? ;-))

One of the things that physicists are looking for is how to connect the Standard Model with all the bits that cannot yet be explained. They are looking for a common theory, the one ring to find them all and in the dark matter bind them. ;-) (Roof is up at Center Court, they are back). The Standard Model has particles that have been theorized that would sew up some of these loose ends but there isn’t yet any evidence for these particles, and that’s where the experiments at CERN and other such places around the world come into play.

(On edge of seat whilst watching the long game that Murray lost. Bother. Federer just won a second set).

They think the boson that they announced on July 4 was one of the theoretically predicted bosons – the Higgs boson. This particular boson would explain why different quarks have different masses, and can therefore help in understanding dark matter (amongst other things).

But how does it work?  Imagine a field that surrounds everything (The Force from Star Wars if you like), made up of Higgs bosons (we can’t see it). A quark can get a different mass depending on its properties as it moves through the Higgs field. (Adapted from the BBC: ) There is a room of tennis players (these are bosons in the Higgs field), hanging out having a cup of tea and some cucumber sandwiches (Aww shucks… Murray lost). Then a quark called Federer walks into the room and is swamped by these bosons who want to congratulate him and get his autograph. It will take him some time to get through the room to the other side – he has acquired a large mass because of the special property he has (e.g. a Wimbledon trophy). A couple of minutes later the quark called Murray walks into the room. He won’t attract quite as big a crowd (unless he’s in the UK of course), so he’ll be able to cross the room more quickly, and has a smaller mass. These quarks have a different mass that they have acquired in their interactions with bosons as they move through the Higgs field.  

So finding evidence of the Higgs boson is important because it is the one that explains why things have mass i.e. why things exist! Scientists haven’t outright said that this is the Higgs boson because they need to check some of its other properties to make sure it fits the theory, but it is definitely a new boson and at least one aspect of it matches the predicted properties of the Higgs boson (predicted in the 1960s). We should know sometime next year if this is the one!

<End Major Science Alert>

Questions anyone? Sigh. Well, now Wimbledon is over I suppose I had better start the day… ;-) (next year Murray, next year!) (Congratulations Federer, well played).


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Disclaimer: It’s been a while since I studied particle and quantum physics. J

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