Friday, 13 July 2012

Why is the 'God particle' relevant to me?

Following on from yesterday's analogies about the Higgs Field, in The incomprehensible Higgs! , let's move on to the Higgs particle.  The big issue for many people is this.

"If it takes so much money and energy to prove the existence of this particle, how can it possibly be relevant to me?"

The answer is more interesting than you might expect.

Yesterday I mentioned a few 'fields' that you must have heard of.  The gravitational field affects all of us every day and the magnetic field is one that we are familiar with.

It turns out that there are other 'fields' in the theories of particle physics that you might not have heard of.   Each has been shown to exist, and almost all of them (not gravity so far) have been shown to be associated with something called a 'virtual particle'.  This is a particle that pops into existence, perhaps incredibly briefly and then disappears again.  e.g. In the last century, the so called 'weak force' and its associated particle was predicted and then shown to exist by high energy experiments (like those at CERN) in the 1970s.

This association between fields and particles is not obvious, but almost everyone reading this will be familiar with Einstein's famous equation.

E=mc2

The reason that this is important in modern physics is that it shows how energy (E) can be turned into mass/weight (m) and back again.  In the sub-atomic world, this is happening all the time and everywhere.  Even in a perfect vacuum, tiny but real particles are created from 'nothing' and destroyed, annihilated, to go back to nothing.  This is happening continuously, un-noticed.

In order to do this, energy is 'borrowed' to make mass temporarily, and (VERY) soon afterwards the mass might be turned back into energy.  This mass takes the form of particles called bosons (and I will resist the temptation to demonstrate my ignorance by explaining what that means).  Some bosons created in this way last for the life of the universe, while others only survive for a brief instant before turning back into energy.  Electromagnetic fields produce 'particles' called photons - they can (but usually don't) live for ever.  You perceive them as light and use them as radio waves and microwaves.

Some of the other sub-atomic fields produce W and Z bosons which were predicted decades before their actual discoveries as mentioned above - they always have very short lives.

In the case of the Higgs field, which acts on us all the time in our daily lives without us realising it, the associated Higgs boson has been christened "The God Particle" for reasons that I find much more inexplicable.  (Yes I know who coined the term, but not why they thought it relevant.)

It turns out that the Higgs boson is really heavy.  Physicists had predicted its weight by doing some complicated maths, and they had therefore estimated how much energy was needed to make one of them, (by using Einstein's equation above).  The disturbing answer was that it needed much more energy than could be provided by the world's biggest accelerators, and so they persuaded European governments to join together to fund the construction of the Large Hadron Collider (LHC) at CERN.  It was designed to accelerate particles to higher speeds (and therefore higher energies) than have ever been made by humanity, and to collide two streams of these particles, travelling in opposite directions, therefore doubling the amount of energy involved in the collision.  As they smash together, the energy of the particles is briefly turned into a 'soup' of known and perhaps (hopefully) unknown, short-lived particles.

The trick is to find a way to spot these virtual particles as they disappear back into energy or turn themselves into other particles.

This is what the various experiments at LHC/CERN have been studying.  Two huge detectors, called ATLAS and CMS have been used to study the microscopic contents of the soup.   The physicists studying the data are trying to filter out the things that are already known and spot things that they can't already explain.  One of the 'filters' available to them is to vary the energy of the collisions, so that they can concentrate on the predicted range to see whether they can find a new phenomenon.

Now we hear that they've spotted something often enough to be absolutely sure that it is a new particle.

At the moment it looks as though this is probably the predicted Higgs particle.  It has the right energy - and therefore the right mass.
  • If it is, then there is likely to be a Nobel prize for some people.  
  • If it is not the Higgs, then physicists will have an exciting new mystery to solve, and someone else will win the coveted prize.  

Nobody loses!**

Now there is only one remaining mystery.  If you were a pedant, where would you put the apostrophe in "Higgs boson"?

** Not even the tax payers who funded this adventure!  It costs much less than an average bank!  You are only reading this because of the internet, and that was more-or-less invented at CERN.  I have no complaints about the scale of the investment.

3 comments:

Anonymous said...

Higgs'! Without a doubt. Or to avoid future nomenclature confusion, use the excuse that it is a proper noun and just nix the apostrophe altogether.

Chuck Maddox said...
This comment has been removed by the author.
Chuck Maddox said...

Redacted, because wikipedia proved me wrong. My bad. My stupid, stupid bad.